build(deps): bump actions/checkout from 4.1.2 to 4.1.3

Bumps [actions/checkout](https://github.com/actions/checkout) from 4.1.2 to 4.1.3. - [Release notes](https://github.com/actions/checkout/releases) - [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md) - [Commits](https://github.com/actions/checkout/compare/9bb56186c3b09b4f86b1c65136769dd318469633...1d96c772d19495a3b5c517cd2bc0cb401ea0529f) --- updated-dependencies: - dependency-name: actions/checkout dependency-type: direct:production update-type: version-update:semver-patch ... Signed-off-by: dependabot[bot] <support@github.com>
build(deps): bump golang.org/x/net from 0.22.0 to 0.23.0
2024-04-21 12:31:38 +00:00 · 2024-04-19 17:37:57 -03:00 · 2024-04-19 15:06:28 -03:00 · 2024-04-19 15:06:00 -03:00 · 2024-04-19 15:05:24 -03:00 · 2024-04-19 15:04:59 -03:00
61 changed files with 2031 additions and 3238 deletions
@@ -13,3 +13,6 @@ indent_style = tab

 [{Makefile,*.mk}]
 indent_style = tab
+
+[*.nix]
+indent_size = 2
@@ -0,0 +1,4 @@
+if ! has nix_direnv_version || ! nix_direnv_version 2.3.0; then
+  source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/2.3.0/direnvrc" "sha256-Dmd+j63L84wuzgyjITIfSxSD57Tx7v51DMxVZOsiUD8="
+fi
+use flake . --impure
@@ -11,8 +11,20 @@ jobs:

    steps:
      - name: Check minimum labels
-        uses: mheap/github-action-required-labels@v4
+        uses: mheap/github-action-required-labels@132879b972cb7f2ac593006455875098e73cc7f2 # v5.4.0
        with:
          mode: minimum
          count: 1
-          labels: "release-note/ignore, kind/feature, release-note/new-feature, kind/enhancement, release-note/enhancement, kind/bug, release-note/bug-fix, release-note/breaking-change, release-note/deprecation, area/dependencies, release-note/dependency-update"
+          labels: |
+            release-note/ignore
+            kind/feature
+            release-note/new-feature
+            kind/enhancement
+            release-note/enhancement
+            kind/bug
+            release-note/bug-fix
+            release-note/breaking-change
+            release-note/deprecation
+            area/dependencies
+            release-note/dependency-update
+            release-note/misc
@@ -2,14 +2,14 @@ name: CI

 on:
  push:
-    branches:
-      - master
+    branches: [master]
  pull_request:

 jobs:
  build:
    name: Build
    runs-on: ubuntu-latest
+
    strategy:
      fail-fast: false
      matrix:
@@ -20,13 +20,13 @@ jobs:
            goarch: ppc64

    steps:
-      - name: Set up Go
-        uses: actions/setup-go@v4
-        with:
-          go-version: '1.20'
+      - name: Checkout repository
+        uses: actions/checkout@1d96c772d19495a3b5c517cd2bc0cb401ea0529f # v4.1.3

-      - name: Checkout code
-        uses: actions/checkout@v3
+      - name: Set up Go
+        uses: actions/setup-go@0c52d547c9bc32b1aa3301fd7a9cb496313a4491 # v5.0.0
+        with:
+          go-version: "1.22"

      - name: Build
        run: go build .
@@ -37,49 +37,79 @@ jobs:
  test:
    name: Test
    runs-on: ${{ matrix.os }}
+
    strategy:
      # Fail fast is disabled because there are Go version specific features and tests
      # that should be able to fail independently.
      fail-fast: false
      matrix:
        os: [ubuntu-latest, macos-latest, windows-latest]
-        go: ['1.17', '1.18', '1.19', '1.20']
-    env:
-      GOFLAGS: -mod=readonly
+        go: ["1.20", "1.21", "1.22"]
+        tags: ["", "finder", "viper_bind_struct"]

    steps:
+      - name: Checkout repository
+        uses: actions/checkout@1d96c772d19495a3b5c517cd2bc0cb401ea0529f # v4.1.3
+
      - name: Set up Go
-        uses: actions/setup-go@v4
+        uses: actions/setup-go@0c52d547c9bc32b1aa3301fd7a9cb496313a4491 # v5.0.0
        with:
          go-version: ${{ matrix.go }}

-      - name: Checkout code
-        uses: actions/checkout@v3
-
      - name: Test
-        run: go test -race -v ./...
+        run: go test -race -v -tags '${{ matrix.tags }}' -shuffle=on ./...
        if: runner.os != 'Windows'

      - name: Test (without race detector)
-        run: go test -v ./...
+        run: go test -v -tags '${{ matrix.tags }}' -shuffle=on ./...
        if: runner.os == 'Windows'

  lint:
    name: Lint
    runs-on: ubuntu-latest
-    env:
-      GOFLAGS: -mod=readonly

    steps:
-      - name: Set up Go
-        uses: actions/setup-go@v4
-        with:
-          go-version: '1.20'
+      - name: Checkout repository
+        uses: actions/checkout@1d96c772d19495a3b5c517cd2bc0cb401ea0529f # v4.1.3

-      - name: Checkout code
-        uses: actions/checkout@v3
+      - name: Set up Go
+        uses: actions/setup-go@0c52d547c9bc32b1aa3301fd7a9cb496313a4491 # v5.0.0
+        with:
+          go-version: "1.22"

      - name: Lint
-        uses: golangci/golangci-lint-action@v3
+        uses: golangci/golangci-lint-action@3cfe3a4abbb849e10058ce4af15d205b6da42804 # v4.0.0
        with:
-          version: v1.52.2
+          version: v1.56.1
+
+  dev:
+    name: Developer environment
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@1d96c772d19495a3b5c517cd2bc0cb401ea0529f # v4.1.3
+
+      - name: Set up Nix
+        uses: cachix/install-nix-action@8887e596b4ee1134dae06b98d573bd674693f47c # v26
+        with:
+          extra_nix_config: |
+            access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
+
+      - name: Check
+        run: nix flake check --impure
+
+      - name: Dev shell
+        run: nix develop --impure
+
+  dependency-review:
+    name: Dependency review
+    runs-on: ubuntu-latest
+    if: github.event_name == 'pull_request'
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@1d96c772d19495a3b5c517cd2bc0cb401ea0529f # v4.1.3
+
+      - name: Dependency Review
+        uses: actions/dependency-review-action@5bbc3ba658137598168acb2ab73b21c432dd411b # v4.2.5
@@ -39,11 +39,11 @@ jobs:

    steps:
    - name: Checkout repository
-      uses: actions/checkout@v3
+      uses: actions/checkout@1d96c772d19495a3b5c517cd2bc0cb401ea0529f # v4.1.3

    # Initializes the CodeQL tools for scanning.
    - name: Initialize CodeQL
-      uses: github/codeql-action/init@v2
+      uses: github/codeql-action/init@c7f9125735019aa87cfc361530512d50ea439c71 # v3.25.1
      with:
        languages: ${{ matrix.language }}
        # If you wish to specify custom queries, you can do so here or in a config file.
@@ -54,7 +54,7 @@ jobs:
    # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
    # If this step fails, then you should remove it and run the build manually (see below)
    - name: Autobuild
-      uses: github/codeql-action/autobuild@v2
+      uses: github/codeql-action/autobuild@c7f9125735019aa87cfc361530512d50ea439c71 # v3.25.1

    # ℹ️ Command-line programs to run using the OS shell.
    # 📚 https://git.io/JvXDl
@@ -68,5 +68,5 @@ jobs:
    #   make release

    - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@v2
+      uses: github/codeql-action/analyze@c7f9125735019aa87cfc361530512d50ea439c71 # v3.25.1

@@ -6,7 +6,7 @@ jobs:
  comment:
    runs-on: ubuntu-latest
    steps:
-      - uses: actions/github-script@v6
+      - uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7.0.1
        with:
          github-token: ${{secrets.GITHUB_TOKEN}}
          script: |
@@ -6,7 +6,7 @@ jobs:
  comment:
    runs-on: ubuntu-latest
    steps:
-      - uses: actions/github-script@v6
+      - uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7.0.1
        with:
          github-token: ${{secrets.GITHUB_TOKEN}}
          script: |
@@ -1,4 +1,7 @@
+/.devenv/
+/.direnv/
 /.idea/
+/.pre-commit-config.yaml
 /bin/
 /build/
 /var/
@@ -7,6 +7,16 @@ linters-settings:
            - standard
            - default
            - prefix(github.com/spf13/viper)
+    gocritic:
+        # Enable multiple checks by tags. See "Tags" section in https://github.com/go-critic/go-critic#usage.
+        enabled-tags:
+            - diagnostic
+            - experimental
+            - opinionated
+            - style
+        disabled-checks:
+            - importShadow
+            - unnamedResult
    golint:
        min-confidence: 0
    goimports:
@@ -22,6 +32,8 @@ linters:
        - exhaustive
        - exportloopref
        - gci
+        - gocritic
+        - godot
        - gofmt
        - gofumpt
        - goimports
@@ -62,9 +74,7 @@ linters:
        # - gochecknoinits
        # - gocognit
        # - goconst
-        # - gocritic
        # - gocyclo
-        # - godot
        # - gosec
        # - gosimple
        # - ifshort
@@ -0,0 +1,2 @@
+# TODO: FIXME
+/.github/
@@ -0,0 +1,6 @@
+ignore-from-file: [.gitignore, .yamlignore]
+
+extends: default
+
+rules:
+  line-length: disable
@@ -16,7 +16,7 @@ endif

 # Dependency versions
 GOTESTSUM_VERSION = 1.9.0
-GOLANGCI_VERSION = 1.52.2
+GOLANGCI_VERSION = 1.53.3

 # Add the ability to override some variables
 # Use with care
@@ -29,11 +29,6 @@ clear: ## Clear the working area and the project
 .PHONY: check
 check: test lint ## Run tests and linters

-bin/gotestsum: bin/gotestsum-${GOTESTSUM_VERSION}
-	@ln -sf gotestsum-${GOTESTSUM_VERSION} bin/gotestsum
-bin/gotestsum-${GOTESTSUM_VERSION}:
-	@mkdir -p bin
-	curl -L https://github.com/gotestyourself/gotestsum/releases/download/v${GOTESTSUM_VERSION}/gotestsum_${GOTESTSUM_VERSION}_${OS}_amd64.tar.gz | tar -zOxf - gotestsum > ./bin/gotestsum-${GOTESTSUM_VERSION} && chmod +x ./bin/gotestsum-${GOTESTSUM_VERSION}

 TEST_PKGS ?= ./...
 .PHONY: test
@@ -44,20 +39,36 @@ test: bin/gotestsum ## Run tests
 	@mkdir -p ${BUILD_DIR}
 	bin/gotestsum --no-summary=skipped --junitfile ${BUILD_DIR}/coverage.xml --format ${TEST_FORMAT} -- -race -coverprofile=${BUILD_DIR}/coverage.txt -covermode=atomic $(filter-out -v,${GOARGS}) $(if ${TEST_PKGS},${TEST_PKGS},./...)

-bin/golangci-lint: bin/golangci-lint-${GOLANGCI_VERSION}
-	@ln -sf golangci-lint-${GOLANGCI_VERSION} bin/golangci-lint
-bin/golangci-lint-${GOLANGCI_VERSION}:
-	@mkdir -p bin
-	curl -sfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | bash -s -- -b ./bin/ v${GOLANGCI_VERSION}
-	@mv bin/golangci-lint "$@"
-
 .PHONY: lint
-lint: bin/golangci-lint ## Run linter
-	bin/golangci-lint run
+lint: lint-go lint-yaml
+lint: ## Run linters

-.PHONY: fix
-fix: bin/golangci-lint ## Fix lint violations
-	bin/golangci-lint run --fix
+.PHONY: lint-go
+lint-go:
+	golangci-lint run $(if ${CI},--out-format github-actions,)
+
+.PHONY: lint-yaml
+lint-yaml:
+	yamllint $(if ${CI},-f github,) --no-warnings .
+
+.PHONY: fmt
+fmt: ## Format code
+	golangci-lint run --fix
+
+deps: bin/golangci-lint bin/gotestsum yamllint
+deps: ## Install dependencies
+
+bin/gotestsum:
+	@mkdir -p bin
+	curl -L https://github.com/gotestyourself/gotestsum/releases/download/v${GOTESTSUM_VERSION}/gotestsum_${GOTESTSUM_VERSION}_${OS}_amd64.tar.gz | tar -zOxf - gotestsum > ./bin/gotestsum && chmod +x ./bin/gotestsum
+
+bin/golangci-lint:
+	@mkdir -p bin
+	curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | bash -s -- v${GOLANGCI_VERSION}
+
+.PHONY: yamllint
+yamllint:
+	pip3 install --user yamllint

 # Add custom targets here
 -include custom.mk
@@ -11,7 +11,7 @@
 [![GitHub Workflow Status](https://img.shields.io/github/actions/workflow/status/spf13/viper/ci.yaml?branch=master&style=flat-square)](https://github.com/spf13/viper/actions?query=workflow%3ACI)
 [![Join the chat at https://gitter.im/spf13/viper](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/spf13/viper?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![Go Report Card](https://goreportcard.com/badge/github.com/spf13/viper?style=flat-square)](https://goreportcard.com/report/github.com/spf13/viper)
-![Go Version](https://img.shields.io/badge/go%20version-%3E=1.16-61CFDD.svg?style=flat-square)
+![Go Version](https://img.shields.io/badge/go%20version-%3E=1.20-61CFDD.svg?style=flat-square)
 [![PkgGoDev](https://pkg.go.dev/badge/mod/github.com/spf13/viper)](https://pkg.go.dev/mod/github.com/spf13/viper)

 **Go configuration with fangs!**
@@ -30,6 +30,7 @@ Many Go projects are built using Viper including:
 * [Meshery](https://github.com/meshery/meshery)
 * [Bearer](https://github.com/bearer/bearer)
 * [Coder](https://github.com/coder/coder)
+* [Vitess](https://vitess.io/)


 ## Install
@@ -38,7 +39,7 @@ Many Go projects are built using Viper including:
 go get github.com/spf13/viper
 ```

-**Note:** Viper uses [Go Modules](https://github.com/golang/go/wiki/Modules) to manage dependencies.
+**Note:** Viper uses [Go Modules](https://go.dev/wiki/Modules) to manage dependencies.


 ## What is Viper?
@@ -140,7 +141,7 @@ if err := viper.ReadInConfig(); err != nil {
 // Config file found and successfully parsed
 ```

-*NOTE [since 1.6]:* You can also have a file without an extension and specify the format programmaticaly. For those configuration files that lie in the home of the user without any extension like `.bashrc`
+*NOTE [since 1.6]:* You can also have a file without an extension and specify the format programmatically. For those configuration files that lie in the home of the user without any extension like `.bashrc`

 ### Writing Config Files

@@ -221,6 +222,7 @@ These could be from a command line flag, or from your own application logic.
 ```go
 viper.Set("Verbose", true)
 viper.Set("LogFile", LogFile)
+viper.Set("host.port", 5899)   // set subset
 ```

 ### Registering and Using Aliases
@@ -416,6 +418,8 @@ in a Key/Value store such as etcd or Consul.  These values take precedence over
 default values, but are overridden by configuration values retrieved from disk,
 flags, or environment variables.

+Viper supports multiple hosts. To use, pass a list of endpoints separated by `;`. For example `http://127.0.0.1:4001;http://127.0.0.1:4002`.
+
 Viper uses [crypt](https://github.com/bketelsen/crypt) to retrieve
 configuration from the K/V store, which means that you can store your
 configuration values encrypted and have them automatically decrypted if you have
@@ -487,6 +491,15 @@ err := viper.ReadRemoteConfig()

 Of course, you're allowed to use `SecureRemoteProvider` also

+
+#### NATS
+
+```go
+viper.AddRemoteProvider("nats", "nats://127.0.0.1:4222", "myapp.config")
+viper.SetConfigType("json")
+err := viper.ReadRemoteConfig()
+```
+
 ### Remote Key/Value Store Example - Encrypted

 ```go
@@ -534,24 +547,27 @@ go func(){
 In Viper, there are a few ways to get a value depending on the value’s type.
 The following functions and methods exist:

- * `Get(key string) : interface{}`
+ * `Get(key string) : any`
 * `GetBool(key string) : bool`
 * `GetFloat64(key string) : float64`
 * `GetInt(key string) : int`
 * `GetIntSlice(key string) : []int`
 * `GetString(key string) : string`
- * `GetStringMap(key string) : map[string]interface{}`
+ * `GetStringMap(key string) : map[string]any`
 * `GetStringMapString(key string) : map[string]string`
 * `GetStringSlice(key string) : []string`
 * `GetTime(key string) : time.Time`
 * `GetDuration(key string) : time.Duration`
 * `IsSet(key string) : bool`
- * `AllSettings() : map[string]interface{}`
+ * `AllSettings() : map[string]any`

 One important thing to recognize is that each Get function will return a zero
 value if it’s not found. To check if a given key exists, the `IsSet()` method
 has been provided.

+The zero value will also be returned if the value is set, but fails to parse
+as the requested type.
+
 Example:
 ```go
 viper.GetString("logfile") // case-insensitive Setting & Getting
@@ -709,8 +725,8 @@ etc.

 There are two methods to do this:

- * `Unmarshal(rawVal interface{}) : error`
- * `UnmarshalKey(key string, rawVal interface{}) : error`
+ * `Unmarshal(rawVal any) : error`
+ * `UnmarshalKey(key string, rawVal any) : error`

 Example:

@@ -735,9 +751,9 @@ you have to change the delimiter:
 ```go
 v := viper.NewWithOptions(viper.KeyDelimiter("::"))

-v.SetDefault("chart::values", map[string]interface{}{
-	"ingress": map[string]interface{}{
-		"annotations": map[string]interface{}{
+v.SetDefault("chart::values", map[string]any{
+	"ingress": map[string]any{
+		"annotations": map[string]any{
 			"traefik.frontend.rule.type":                 "PathPrefix",
 			"traefik.ingress.kubernetes.io/ssl-redirect": "true",
 		},
@@ -746,7 +762,7 @@ v.SetDefault("chart::values", map[string]interface{}{

 type config struct {
 	Chart struct{
-		Values map[string]interface{}
+		Values map[string]any
 	}
 }

@@ -882,3 +898,31 @@ No, you will need to synchronize access to the viper yourself (for example by us
 ## Troubleshooting

 See [TROUBLESHOOTING.md](TROUBLESHOOTING.md).
+
+## Development
+
+**For an optimal developer experience, it is recommended to install [Nix](https://nixos.org/download.html) and [direnv](https://direnv.net/docs/installation.html).**
+
+_Alternatively, install [Go](https://go.dev/dl/) on your computer then run `make deps` to install the rest of the dependencies._
+
+Run the test suite:
+
+```shell
+make test
+```
+
+Run linters:
+
+```shell
+make lint # pass -j option to run them in parallel
+```
+
+Some linter violations can automatically be fixed:
+
+```shell
+make fmt
+```
+
+## License
+
+The project is licensed under the [MIT License](LICENSE).
@@ -15,10 +15,10 @@ cannot find package "github.com/hashicorp/hcl/tree/hcl1" in any of:
 ```

 As the error message suggests, Go tries to look up dependencies in `GOPATH` mode (as it's commonly called) from the `GOPATH`.
-Viper opted to use [Go Modules](https://github.com/golang/go/wiki/Modules) to manage its dependencies. While in many cases the two methods are interchangeable, once a dependency releases new (major) versions, `GOPATH` mode is no longer able to decide which version to use, so it'll either use one that's already present or pick a version (usually the `master` branch).
+Viper opted to use [Go Modules](https://go.dev/wiki/Modules) to manage its dependencies. While in many cases the two methods are interchangeable, once a dependency releases new (major) versions, `GOPATH` mode is no longer able to decide which version to use, so it'll either use one that's already present or pick a version (usually the `master` branch).

 The solution is easy: switch to using Go Modules.
-Please refer to the [wiki](https://github.com/golang/go/wiki/Modules) on how to do that.
+Please refer to the [wiki](https://go.dev/wiki/Modules) on how to do that.

 **tl;dr* `export GO111MODULE=on`

@@ -1,11 +0,0 @@
-//go:build viper_logger
-// +build viper_logger
-
-package viper
-
-// WithLogger sets a custom logger.
-func WithLogger(l Logger) Option {
-	return optionFunc(func(v *Viper) {
-		v.logger = l
-	})
-}
@@ -1,5 +1,4 @@
-//go:build !go1.16 || !finder
-// +build !go1.16 !finder
+//go:build !finder

 package viper

@@ -44,7 +43,7 @@ func (v *Viper) searchInPath(in string) (filename string) {
 	return ""
 }

-// Check if file Exists
+// exists checks if file exists.
 func exists(fs afero.Fs, path string) (bool, error) {
 	stat, err := fs.Stat(path)
 	if err == nil {
@@ -0,0 +1,38 @@
+//go:build finder
+
+package viper
+
+import (
+	"fmt"
+
+	"github.com/sagikazarmark/locafero"
+)
+
+// Search all configPaths for any config file.
+// Returns the first path that exists (and is a config file).
+func (v *Viper) findConfigFile() (string, error) {
+	var names []string
+
+	if v.configType != "" {
+		names = locafero.NameWithOptionalExtensions(v.configName, SupportedExts...)
+	} else {
+		names = locafero.NameWithExtensions(v.configName, SupportedExts...)
+	}
+
+	finder := locafero.Finder{
+		Paths: v.configPaths,
+		Names: names,
+		Type:  locafero.FileTypeFile,
+	}
+
+	results, err := finder.Find(v.fs)
+	if err != nil {
+		return "", err
+	}
+
+	if len(results) == 0 {
+		return "", ConfigFileNotFoundError{v.configName, fmt.Sprintf("%s", v.configPaths)}
+	}
+
+	return results[0], nil
+}
@@ -30,8 +30,8 @@ func (p pflagValueSet) VisitAll(fn func(flag FlagValue)) {
 	})
 }

-// pflagValue is a wrapper aroung *pflag.flag
-// that implements FlagValue
+// pflagValue is a wrapper around *pflag.flag
+// that implements FlagValue.
 type pflagValue struct {
 	flag *pflag.Flag
 }
@@ -5,9 +5,11 @@ import (

 	"github.com/spf13/pflag"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )

 func TestBindFlagValueSet(t *testing.T) {
+	Reset()
 	flagSet := pflag.NewFlagSet("test", pflag.ContinueOnError)

 	testValues := map[string]*string{
@@ -29,9 +31,7 @@ func TestBindFlagValueSet(t *testing.T) {
 	flagValueSet := pflagValueSet{flagSet}

 	err := BindFlagValues(flagValueSet)
-	if err != nil {
-		t.Fatalf("error binding flag set, %v", err)
-	}
+	require.NoError(t, err, "error binding flag set")

 	flagSet.VisitAll(func(flag *pflag.Flag) {
 		flag.Value.Set(mutatedTestValues[flag.Name])
@@ -39,7 +39,7 @@ func TestBindFlagValueSet(t *testing.T) {
 	})

 	for name, expected := range mutatedTestValues {
-		assert.Equal(t, Get(name), expected)
+		assert.Equal(t, expected, Get(name))
 	}
 }

@@ -0,0 +1,273 @@
+{
+  "nodes": {
+    "devenv": {
+      "inputs": {
+        "flake-compat": "flake-compat",
+        "nix": "nix",
+        "nixpkgs": "nixpkgs",
+        "pre-commit-hooks": "pre-commit-hooks"
+      },
+      "locked": {
+        "lastModified": 1707817777,
+        "narHash": "sha256-vHyIs1OULQ3/91wD6xOiuayfI71JXALGA5KLnDKAcy0=",
+        "owner": "cachix",
+        "repo": "devenv",
+        "rev": "5a30b9e5ac7c6167e61b1f4193d5130bb9f8defa",
+        "type": "github"
+      },
+      "original": {
+        "owner": "cachix",
+        "repo": "devenv",
+        "type": "github"
+      }
+    },
+    "flake-compat": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1673956053,
+        "narHash": "sha256-4gtG9iQuiKITOjNQQeQIpoIB6b16fm+504Ch3sNKLd8=",
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "rev": "35bb57c0c8d8b62bbfd284272c928ceb64ddbde9",
+        "type": "github"
+      },
+      "original": {
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
+    "flake-parts": {
+      "inputs": {
+        "nixpkgs-lib": "nixpkgs-lib"
+      },
+      "locked": {
+        "lastModified": 1706830856,
+        "narHash": "sha256-a0NYyp+h9hlb7ddVz4LUn1vT/PLwqfrWYcHMvFB1xYg=",
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "rev": "b253292d9c0a5ead9bc98c4e9a26c6312e27d69f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "type": "github"
+      }
+    },
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1685518550,
+        "narHash": "sha256-o2d0KcvaXzTrPRIo0kOLV0/QXHhDQ5DTi+OxcjO8xqY=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "a1720a10a6cfe8234c0e93907ffe81be440f4cef",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "gitignore": {
+      "inputs": {
+        "nixpkgs": [
+          "devenv",
+          "pre-commit-hooks",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1660459072,
+        "narHash": "sha256-8DFJjXG8zqoONA1vXtgeKXy68KdJL5UaXR8NtVMUbx8=",
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "rev": "a20de23b925fd8264fd7fad6454652e142fd7f73",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "type": "github"
+      }
+    },
+    "lowdown-src": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1633514407,
+        "narHash": "sha256-Dw32tiMjdK9t3ETl5fzGrutQTzh2rufgZV4A/BbxuD4=",
+        "owner": "kristapsdz",
+        "repo": "lowdown",
+        "rev": "d2c2b44ff6c27b936ec27358a2653caaef8f73b8",
+        "type": "github"
+      },
+      "original": {
+        "owner": "kristapsdz",
+        "repo": "lowdown",
+        "type": "github"
+      }
+    },
+    "nix": {
+      "inputs": {
+        "lowdown-src": "lowdown-src",
+        "nixpkgs": [
+          "devenv",
+          "nixpkgs"
+        ],
+        "nixpkgs-regression": "nixpkgs-regression"
+      },
+      "locked": {
+        "lastModified": 1676545802,
+        "narHash": "sha256-EK4rZ+Hd5hsvXnzSzk2ikhStJnD63odF7SzsQ8CuSPU=",
+        "owner": "domenkozar",
+        "repo": "nix",
+        "rev": "7c91803598ffbcfe4a55c44ac6d49b2cf07a527f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "domenkozar",
+        "ref": "relaxed-flakes",
+        "repo": "nix",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1678875422,
+        "narHash": "sha256-T3o6NcQPwXjxJMn2shz86Chch4ljXgZn746c2caGxd8=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "126f49a01de5b7e35a43fd43f891ecf6d3a51459",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-lib": {
+      "locked": {
+        "dir": "lib",
+        "lastModified": 1706550542,
+        "narHash": "sha256-UcsnCG6wx++23yeER4Hg18CXWbgNpqNXcHIo5/1Y+hc=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "97b17f32362e475016f942bbdfda4a4a72a8a652",
+        "type": "github"
+      },
+      "original": {
+        "dir": "lib",
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-regression": {
+      "locked": {
+        "lastModified": 1643052045,
+        "narHash": "sha256-uGJ0VXIhWKGXxkeNnq4TvV3CIOkUJ3PAoLZ3HMzNVMw=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "215d4d0fd80ca5163643b03a33fde804a29cc1e2",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "215d4d0fd80ca5163643b03a33fde804a29cc1e2",
+        "type": "github"
+      }
+    },
+    "nixpkgs-stable": {
+      "locked": {
+        "lastModified": 1685801374,
+        "narHash": "sha256-otaSUoFEMM+LjBI1XL/xGB5ao6IwnZOXc47qhIgJe8U=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "c37ca420157f4abc31e26f436c1145f8951ff373",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-23.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_2": {
+      "locked": {
+        "lastModified": 1707939175,
+        "narHash": "sha256-D1xan0lgxbmXDyzVqXTiSYHLmAMrMRdD+alKzEO/p3w=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "f7e8132daca31b1e3859ac0fb49741754375ac3d",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "pre-commit-hooks": {
+      "inputs": {
+        "flake-compat": [
+          "devenv",
+          "flake-compat"
+        ],
+        "flake-utils": "flake-utils",
+        "gitignore": "gitignore",
+        "nixpkgs": [
+          "devenv",
+          "nixpkgs"
+        ],
+        "nixpkgs-stable": "nixpkgs-stable"
+      },
+      "locked": {
+        "lastModified": 1704725188,
+        "narHash": "sha256-qq8NbkhRZF1vVYQFt1s8Mbgo8knj+83+QlL5LBnYGpI=",
+        "owner": "cachix",
+        "repo": "pre-commit-hooks.nix",
+        "rev": "ea96f0c05924341c551a797aaba8126334c505d2",
+        "type": "github"
+      },
+      "original": {
+        "owner": "cachix",
+        "repo": "pre-commit-hooks.nix",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "devenv": "devenv",
+        "flake-parts": "flake-parts",
+        "nixpkgs": "nixpkgs_2"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
@@ -0,0 +1,57 @@
+{
+  description = "Viper";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    flake-parts.url = "github:hercules-ci/flake-parts";
+    devenv.url = "github:cachix/devenv";
+  };
+
+  outputs = inputs@{ flake-parts, ... }:
+    flake-parts.lib.mkFlake { inherit inputs; } {
+      imports = [
+        inputs.devenv.flakeModule
+      ];
+
+      systems = [ "x86_64-linux" "x86_64-darwin" "aarch64-darwin" ];
+
+      perSystem = { config, self', inputs', pkgs, system, ... }: rec {
+        devenv.shells = {
+          default = {
+            languages = {
+              go.enable = true;
+              go.package = pkgs.go_1_22;
+            };
+
+            pre-commit.hooks = {
+              nixpkgs-fmt.enable = true;
+              yamllint.enable = true;
+            };
+
+            packages = with pkgs; [
+              gnumake
+
+              golangci-lint
+              yamllint
+            ];
+
+            scripts = {
+              versions.exec = ''
+                go version
+                golangci-lint version
+              '';
+            };
+
+            enterShell = ''
+              versions
+            '';
+
+            # https://github.com/cachix/devenv/issues/528#issuecomment-1556108767
+            containers = pkgs.lib.mkForce { };
+          };
+
+          ci = devenv.shells.default;
+        };
+      };
+    };
+}
@@ -1,65 +0,0 @@
-//go:build go1.16 && finder
-// +build go1.16,finder
-
-package viper
-
-import (
-	"errors"
-	"io/fs"
-	"path"
-)
-
-type finder struct {
-	paths      []string
-	fileNames  []string
-	extensions []string
-
-	withoutExtension bool
-}
-
-func (f finder) Find(fsys fs.FS) (string, error) {
-	for _, searchPath := range f.paths {
-		for _, fileName := range f.fileNames {
-			for _, extension := range f.extensions {
-				filePath := path.Join(searchPath, fileName+"."+extension)
-
-				ok, err := fileExists(fsys, filePath)
-				if err != nil {
-					return "", err
-				}
-
-				if ok {
-					return filePath, nil
-				}
-			}
-
-			if f.withoutExtension {
-				filePath := path.Join(searchPath, fileName)
-
-				ok, err := fileExists(fsys, filePath)
-				if err != nil {
-					return "", err
-				}
-
-				if ok {
-					return filePath, nil
-				}
-			}
-		}
-	}
-
-	return "", nil
-}
-
-func fileExists(fsys fs.FS, filePath string) (bool, error) {
-	fileInfo, err := fs.Stat(fsys, filePath)
-	if err == nil {
-		return !fileInfo.IsDir(), nil
-	}
-
-	if errors.Is(err, fs.ErrNotExist) {
-		return false, nil
-	}
-
-	return false, err
-}
@@ -1,100 +0,0 @@
-//go:build go1.16 && finder
-// +build go1.16,finder
-
-package viper
-
-import (
-	"io/fs"
-	"testing"
-	"testing/fstest"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-func TestFinder(t *testing.T) {
-	t.Parallel()
-
-	fsys := fstest.MapFS{
-		"home/user/.config":            &fstest.MapFile{},
-		"home/user/config.json":        &fstest.MapFile{},
-		"home/user/config.yaml":        &fstest.MapFile{},
-		"home/user/data.json":          &fstest.MapFile{},
-		"etc/config/.config":           &fstest.MapFile{},
-		"etc/config/a_random_file.txt": &fstest.MapFile{},
-		"etc/config/config.json":       &fstest.MapFile{},
-		"etc/config/config.yaml":       &fstest.MapFile{},
-		"etc/config/config.xml":        &fstest.MapFile{},
-	}
-
-	testCases := []struct {
-		name   string
-		fsys   func() fs.FS
-		finder finder
-		result string
-	}{
-		{
-			name: "find file",
-			fsys: func() fs.FS { return fsys },
-			finder: finder{
-				paths:      []string{"etc/config"},
-				fileNames:  []string{"config"},
-				extensions: []string{"json"},
-			},
-			result: "etc/config/config.json",
-		},
-		{
-			name: "file not found",
-			fsys: func() fs.FS { return fsys },
-			finder: finder{
-				paths:      []string{"var/config"},
-				fileNames:  []string{"config"},
-				extensions: []string{"json"},
-			},
-			result: "",
-		},
-		{
-			name:   "empty search params",
-			fsys:   func() fs.FS { return fsys },
-			finder: finder{},
-			result: "",
-		},
-		{
-			name: "precedence",
-			fsys: func() fs.FS { return fsys },
-			finder: finder{
-				paths:      []string{"var/config", "home/user", "etc/config"},
-				fileNames:  []string{"aconfig", "config"},
-				extensions: []string{"zml", "xml", "json"},
-			},
-			result: "home/user/config.json",
-		},
-		{
-			name: "without extension",
-			fsys: func() fs.FS { return fsys },
-			finder: finder{
-				paths:      []string{"var/config", "home/user", "etc/config"},
-				fileNames:  []string{".config"},
-				extensions: []string{"zml", "xml", "json"},
-
-				withoutExtension: true,
-			},
-			result: "home/user/.config",
-		},
-	}
-
-	for _, testCase := range testCases {
-		testCase := testCase
-
-		t.Run(testCase.name, func(t *testing.T) {
-			t.Parallel()
-
-			fsys := testCase.fsys()
-
-			result, err := testCase.finder.Find(fsys)
-			require.NoError(t, err)
-
-			assert.Equal(t, testCase.result, result)
-		})
-	}
-}
@@ -1,76 +1,93 @@
 module github.com/spf13/viper

-go 1.17
+go 1.20

 require (
-	github.com/fsnotify/fsnotify v1.6.0
+	github.com/fsnotify/fsnotify v1.7.0
 	github.com/hashicorp/hcl v1.0.0
 	github.com/magiconair/properties v1.8.7
 	github.com/mitchellh/mapstructure v1.5.0
-	github.com/pelletier/go-toml/v2 v2.0.8
-	github.com/sagikazarmark/crypt v0.10.0
-	github.com/spf13/afero v1.9.5
-	github.com/spf13/cast v1.5.1
-	github.com/spf13/jwalterweatherman v1.1.0
+	github.com/pelletier/go-toml/v2 v2.2.1
+	github.com/sagikazarmark/crypt v0.19.0
+	github.com/sagikazarmark/locafero v0.4.0
+	github.com/sagikazarmark/slog-shim v0.1.0
+	github.com/spf13/afero v1.11.0
+	github.com/spf13/cast v1.6.0
 	github.com/spf13/pflag v1.0.5
-	github.com/stretchr/testify v1.8.3
-	github.com/subosito/gotenv v1.4.2
+	github.com/stretchr/testify v1.9.0
+	github.com/subosito/gotenv v1.6.0
 	gopkg.in/ini.v1 v1.67.0
 	gopkg.in/yaml.v3 v3.0.1
 )

 require (
-	cloud.google.com/go v0.110.0 // indirect
-	cloud.google.com/go/compute v1.19.0 // indirect
+	cloud.google.com/go v0.112.1 // indirect
+	cloud.google.com/go/compute v1.24.0 // indirect
 	cloud.google.com/go/compute/metadata v0.2.3 // indirect
-	cloud.google.com/go/firestore v1.9.0 // indirect
-	cloud.google.com/go/longrunning v0.4.1 // indirect
-	github.com/armon/go-metrics v0.4.0 // indirect
+	cloud.google.com/go/firestore v1.15.0 // indirect
+	cloud.google.com/go/longrunning v0.5.5 // indirect
+	github.com/armon/go-metrics v0.4.1 // indirect
 	github.com/coreos/go-semver v0.3.0 // indirect
 	github.com/coreos/go-systemd/v22 v22.3.2 // indirect
-	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/fatih/color v1.13.0 // indirect
+	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
+	github.com/fatih/color v1.14.1 // indirect
+	github.com/felixge/httpsnoop v1.0.4 // indirect
+	github.com/go-logr/logr v1.4.1 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
 	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
 	github.com/golang/protobuf v1.5.3 // indirect
-	github.com/google/go-cmp v0.5.9 // indirect
-	github.com/google/s2a-go v0.1.3 // indirect
-	github.com/googleapis/enterprise-certificate-proxy v0.2.3 // indirect
-	github.com/googleapis/gax-go/v2 v2.8.0 // indirect
-	github.com/hashicorp/consul/api v1.20.0 // indirect
+	github.com/google/s2a-go v0.1.7 // indirect
+	github.com/googleapis/enterprise-certificate-proxy v0.3.2 // indirect
+	github.com/googleapis/gax-go/v2 v2.12.3 // indirect
+	github.com/hashicorp/consul/api v1.28.2 // indirect
+	github.com/hashicorp/errwrap v1.1.0 // indirect
 	github.com/hashicorp/go-cleanhttp v0.5.2 // indirect
-	github.com/hashicorp/go-hclog v1.2.0 // indirect
+	github.com/hashicorp/go-hclog v1.5.0 // indirect
 	github.com/hashicorp/go-immutable-radix v1.3.1 // indirect
+	github.com/hashicorp/go-multierror v1.1.1 // indirect
 	github.com/hashicorp/go-rootcerts v1.0.2 // indirect
 	github.com/hashicorp/golang-lru v0.5.4 // indirect
 	github.com/hashicorp/serf v0.10.1 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
-	github.com/mattn/go-colorable v0.1.12 // indirect
-	github.com/mattn/go-isatty v0.0.14 // indirect
+	github.com/klauspost/compress v1.17.2 // indirect
+	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-isatty v0.0.17 // indirect
 	github.com/mitchellh/go-homedir v1.1.0 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/nats-io/nats.go v1.34.0 // indirect
+	github.com/nats-io/nkeys v0.4.7 // indirect
+	github.com/nats-io/nuid v1.0.1 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
-	github.com/pmezard/go-difflib v1.0.0 // indirect
-	go.etcd.io/etcd/api/v3 v3.5.9 // indirect
-	go.etcd.io/etcd/client/pkg/v3 v3.5.9 // indirect
-	go.etcd.io/etcd/client/v2 v2.305.7 // indirect
-	go.etcd.io/etcd/client/v3 v3.5.9 // indirect
+	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
+	github.com/sourcegraph/conc v0.3.0 // indirect
+	go.etcd.io/etcd/api/v3 v3.5.12 // indirect
+	go.etcd.io/etcd/client/pkg/v3 v3.5.12 // indirect
+	go.etcd.io/etcd/client/v2 v2.305.12 // indirect
+	go.etcd.io/etcd/client/v3 v3.5.12 // indirect
 	go.opencensus.io v0.24.0 // indirect
+	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.49.0 // indirect
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.49.0 // indirect
+	go.opentelemetry.io/otel v1.24.0 // indirect
+	go.opentelemetry.io/otel/metric v1.24.0 // indirect
+	go.opentelemetry.io/otel/trace v1.24.0 // indirect
 	go.uber.org/atomic v1.9.0 // indirect
-	go.uber.org/multierr v1.8.0 // indirect
+	go.uber.org/multierr v1.9.0 // indirect
 	go.uber.org/zap v1.21.0 // indirect
-	golang.org/x/crypto v0.9.0 // indirect
-	golang.org/x/net v0.10.0 // indirect
-	golang.org/x/oauth2 v0.7.0 // indirect
-	golang.org/x/sync v0.1.0 // indirect
-	golang.org/x/sys v0.8.0 // indirect
-	golang.org/x/text v0.9.0 // indirect
-	golang.org/x/time v0.1.0 // indirect
-	golang.org/x/xerrors v0.0.0-20220907171357-04be3eba64a2 // indirect
-	google.golang.org/api v0.122.0 // indirect
-	google.golang.org/appengine v1.6.7 // indirect
-	google.golang.org/genproto v0.0.0-20230410155749-daa745c078e1 // indirect
-	google.golang.org/grpc v1.55.0 // indirect
-	google.golang.org/protobuf v1.30.0 // indirect
+	golang.org/x/crypto v0.21.0 // indirect
+	golang.org/x/exp v0.0.0-20230905200255-921286631fa9 // indirect
+	golang.org/x/net v0.23.0 // indirect
+	golang.org/x/oauth2 v0.18.0 // indirect
+	golang.org/x/sync v0.6.0 // indirect
+	golang.org/x/sys v0.18.0 // indirect
+	golang.org/x/text v0.14.0 // indirect
+	golang.org/x/time v0.5.0 // indirect
+	google.golang.org/api v0.171.0 // indirect
+	google.golang.org/appengine v1.6.8 // indirect
+	google.golang.org/genproto v0.0.0-20240213162025-012b6fc9bca9 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20240311132316-a219d84964c2 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20240314234333-6e1732d8331c // indirect
+	google.golang.org/grpc v1.62.1 // indirect
+	google.golang.org/protobuf v1.33.0 // indirect
 )
@@ -5,9 +5,9 @@ import (
 )

 // Decoder decodes the contents of b into v.
-// It's primarily used for decoding contents of a file into a map[string]interface{}.
+// It's primarily used for decoding contents of a file into a map[string]any.
 type Decoder interface {
-	Decode(b []byte, v map[string]interface{}) error
+	Decode(b []byte, v map[string]any) error
 }

 const (
@@ -48,7 +48,7 @@ func (e *DecoderRegistry) RegisterDecoder(format string, enc Decoder) error {
 }

 // Decode calls the underlying Decoder based on the format.
-func (e *DecoderRegistry) Decode(format string, b []byte, v map[string]interface{}) error {
+func (e *DecoderRegistry) Decode(format string, b []byte, v map[string]any) error {
 	e.mu.RLock()
 	decoder, ok := e.decoders[format]
 	e.mu.RUnlock()
@@ -1,15 +1,17 @@
 package encoding

 import (
-	"reflect"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )

 type decoder struct {
-	v map[string]interface{}
+	v map[string]any
 }

-func (d decoder) Decode(_ []byte, v map[string]interface{}) error {
+func (d decoder) Decode(_ []byte, v map[string]any) error {
 	for key, value := range d.v {
 		v[key] = value
 	}
@@ -22,23 +24,17 @@ func TestDecoderRegistry_RegisterDecoder(t *testing.T) {
 		registry := NewDecoderRegistry()

 		err := registry.RegisterDecoder("myformat", decoder{})
-		if err != nil {
-			t.Fatal(err)
-		}
+		require.NoError(t, err)
 	})

 	t.Run("AlreadyRegistered", func(t *testing.T) {
 		registry := NewDecoderRegistry()

 		err := registry.RegisterDecoder("myformat", decoder{})
-		if err != nil {
-			t.Fatal(err)
-		}
+		require.NoError(t, err)

 		err = registry.RegisterDecoder("myformat", decoder{})
-		if err != ErrDecoderFormatAlreadyRegistered {
-			t.Fatalf("expected ErrDecoderFormatAlreadyRegistered, got: %v", err)
-		}
+		assert.ErrorIs(t, err, ErrDecoderFormatAlreadyRegistered)
 	})
 }

@@ -46,36 +42,28 @@ func TestDecoderRegistry_Decode(t *testing.T) {
 	t.Run("OK", func(t *testing.T) {
 		registry := NewDecoderRegistry()
 		decoder := decoder{
-			v: map[string]interface{}{
+			v: map[string]any{
 				"key": "value",
 			},
 		}

 		err := registry.RegisterDecoder("myformat", decoder)
-		if err != nil {
-			t.Fatal(err)
-		}
+		require.NoError(t, err)

-		v := map[string]interface{}{}
+		v := map[string]any{}

 		err = registry.Decode("myformat", []byte("key: value"), v)
-		if err != nil {
-			t.Fatal(err)
-		}
+		require.NoError(t, err)

-		if !reflect.DeepEqual(decoder.v, v) {
-			t.Fatalf("decoded value does not match the expected one\nactual:   %+v\nexpected: %+v", v, decoder.v)
-		}
+		assert.Equal(t, decoder.v, v)
 	})

 	t.Run("DecoderNotFound", func(t *testing.T) {
 		registry := NewDecoderRegistry()

-		v := map[string]interface{}{}
+		v := map[string]any{}

 		err := registry.Decode("myformat", nil, v)
-		if err != ErrDecoderNotFound {
-			t.Fatalf("expected ErrDecoderNotFound, got: %v", err)
-		}
+		assert.ErrorIs(t, err, ErrDecoderNotFound)
 	})
 }
@@ -15,8 +15,8 @@ const keyDelimiter = "_"
 // (commonly called as dotenv format).
 type Codec struct{}

-func (Codec) Encode(v map[string]interface{}) ([]byte, error) {
-	flattened := map[string]interface{}{}
+func (Codec) Encode(v map[string]any) ([]byte, error) {
+	flattened := map[string]any{}

 	flattened = flattenAndMergeMap(flattened, v, "", keyDelimiter)

@@ -40,7 +40,7 @@ func (Codec) Encode(v map[string]interface{}) ([]byte, error) {
 	return buf.Bytes(), nil
 }

-func (Codec) Decode(b []byte, v map[string]interface{}) error {
+func (Codec) Decode(b []byte, v map[string]any) error {
 	var buf bytes.Buffer

 	_, err := buf.Write(b)
@@ -1,21 +1,23 @@
 package dotenv

 import (
-	"reflect"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )

-// original form of the data
+// original form of the data.
 const original = `# key-value pair
 KEY=value
 `

-// encoded form of the data
+// encoded form of the data.
 const encoded = `KEY=value
 `

-// Viper's internal representation
-var data = map[string]interface{}{
+// data is Viper's internal representation.
+var data = map[string]any{
 	"KEY": "value",
 }

@@ -23,40 +25,30 @@ func TestCodec_Encode(t *testing.T) {
 	codec := Codec{}

 	b, err := codec.Encode(data)
-	if err != nil {
-		t.Fatal(err)
-	}
+	require.NoError(t, err)

-	if encoded != string(b) {
-		t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", string(b), encoded)
-	}
+	assert.Equal(t, encoded, string(b))
 }

 func TestCodec_Decode(t *testing.T) {
 	t.Run("OK", func(t *testing.T) {
 		codec := Codec{}

-		v := map[string]interface{}{}
+		v := map[string]any{}

 		err := codec.Decode([]byte(original), v)
-		if err != nil {
-			t.Fatal(err)
-		}
+		require.NoError(t, err)

-		if !reflect.DeepEqual(data, v) {
-			t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", v, data)
-		}
+		assert.Equal(t, data, v)
 	})

 	t.Run("InvalidData", func(t *testing.T) {
 		codec := Codec{}

-		v := map[string]interface{}{}
+		v := map[string]any{}

 		err := codec.Decode([]byte(`invalid data`), v)
-		if err == nil {
-			t.Fatal("expected decoding to fail")
-		}
+		require.Error(t, err)

 		t.Logf("decoding failed as expected: %s", err)
 	})
@@ -7,27 +7,27 @@ import (
 )

 // flattenAndMergeMap recursively flattens the given map into a new map
-// Code is based on the function with the same name in tha main package.
-// TODO: move it to a common place
-func flattenAndMergeMap(shadow map[string]interface{}, m map[string]interface{}, prefix string, delimiter string) map[string]interface{} {
+// Code is based on the function with the same name in the main package.
+// TODO: move it to a common place.
+func flattenAndMergeMap(shadow, m map[string]any, prefix, delimiter string) map[string]any {
 	if shadow != nil && prefix != "" && shadow[prefix] != nil {
 		// prefix is shadowed => nothing more to flatten
 		return shadow
 	}
 	if shadow == nil {
-		shadow = make(map[string]interface{})
+		shadow = make(map[string]any)
 	}

-	var m2 map[string]interface{}
+	var m2 map[string]any
 	if prefix != "" {
 		prefix += delimiter
 	}
 	for k, val := range m {
 		fullKey := prefix + k
-		switch val.(type) {
-		case map[string]interface{}:
-			m2 = val.(map[string]interface{})
-		case map[interface{}]interface{}:
+		switch val := val.(type) {
+		case map[string]any:
+			m2 = val
+		case map[any]any:
 			m2 = cast.ToStringMap(val)
 		default:
 			// immediate value
@@ -5,9 +5,9 @@ import (
 )

 // Encoder encodes the contents of v into a byte representation.
-// It's primarily used for encoding a map[string]interface{} into a file format.
+// It's primarily used for encoding a map[string]any into a file format.
 type Encoder interface {
-	Encode(v map[string]interface{}) ([]byte, error)
+	Encode(v map[string]any) ([]byte, error)
 }

 const (
@@ -47,7 +47,7 @@ func (e *EncoderRegistry) RegisterEncoder(format string, enc Encoder) error {
 	return nil
 }

-func (e *EncoderRegistry) Encode(format string, v map[string]interface{}) ([]byte, error) {
+func (e *EncoderRegistry) Encode(format string, v map[string]any) ([]byte, error) {
 	e.mu.RLock()
 	encoder, ok := e.encoders[format]
 	e.mu.RUnlock()
@@ -2,13 +2,16 @@ package encoding

 import (
 	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )

 type encoder struct {
 	b []byte
 }

-func (e encoder) Encode(_ map[string]interface{}) ([]byte, error) {
+func (e encoder) Encode(_ map[string]any) ([]byte, error) {
 	return e.b, nil
 }

@@ -17,23 +20,17 @@ func TestEncoderRegistry_RegisterEncoder(t *testing.T) {
 		registry := NewEncoderRegistry()

 		err := registry.RegisterEncoder("myformat", encoder{})
-		if err != nil {
-			t.Fatal(err)
-		}
+		require.NoError(t, err)
 	})

 	t.Run("AlreadyRegistered", func(t *testing.T) {
 		registry := NewEncoderRegistry()

 		err := registry.RegisterEncoder("myformat", encoder{})
-		if err != nil {
-			t.Fatal(err)
-		}
+		require.NoError(t, err)

 		err = registry.RegisterEncoder("myformat", encoder{})
-		if err != ErrEncoderFormatAlreadyRegistered {
-			t.Fatalf("expected ErrEncoderFormatAlreadyRegistered, got: %v", err)
-		}
+		assert.ErrorIs(t, err, ErrEncoderFormatAlreadyRegistered)
 	})
 }

@@ -45,26 +42,18 @@ func TestEncoderRegistry_Decode(t *testing.T) {
 		}

 		err := registry.RegisterEncoder("myformat", encoder)
-		if err != nil {
-			t.Fatal(err)
-		}
+		require.NoError(t, err)

-		b, err := registry.Encode("myformat", map[string]interface{}{"key": "value"})
-		if err != nil {
-			t.Fatal(err)
-		}
+		b, err := registry.Encode("myformat", map[string]any{"key": "value"})
+		require.NoError(t, err)

-		if string(b) != "key: value" {
-			t.Fatalf("expected 'key: value', got: %#v", string(b))
-		}
+		assert.Equal(t, "key: value", string(b))
 	})

 	t.Run("EncoderNotFound", func(t *testing.T) {
 		registry := NewEncoderRegistry()

-		_, err := registry.Encode("myformat", map[string]interface{}{"key": "value"})
-		if err != ErrEncoderNotFound {
-			t.Fatalf("expected ErrEncoderNotFound, got: %v", err)
-		}
+		_, err := registry.Encode("myformat", map[string]any{"key": "value"})
+		assert.ErrorIs(t, err, ErrEncoderNotFound)
 	})
 }
@@ -12,7 +12,7 @@ import (
 // TODO: add printer config to the codec?
 type Codec struct{}

-func (Codec) Encode(v map[string]interface{}) ([]byte, error) {
+func (Codec) Encode(v map[string]any) ([]byte, error) {
 	b, err := json.Marshal(v)
 	if err != nil {
 		return nil, err
@@ -35,6 +35,6 @@ func (Codec) Encode(v map[string]interface{}) ([]byte, error) {
 	return buf.Bytes(), nil
 }

-func (Codec) Decode(b []byte, v map[string]interface{}) error {
+func (Codec) Decode(b []byte, v map[string]any) error {
 	return hcl.Unmarshal(b, &v)
 }
@@ -1,11 +1,13 @@
 package hcl

 import (
-	"reflect"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )

-// original form of the data
+// original form of the data.
 const original = `# key-value pair
 "key" = "value"

@@ -26,7 +28,7 @@ nested map
  "list" = ["item1", "item2", "item3"]
 }`

-// encoded form of the data
+// encoded form of the data.
 const encoded = `"key" = "value"

 "list" = ["item1", "item2", "item3"]
@@ -41,28 +43,28 @@ const encoded = `"key" = "value"
  "list" = ["item1", "item2", "item3"]
 }`

-// decoded form of the data
+// decoded form of the data.
 //
-// in case of HCL it's slightly different from Viper's internal representation
-// (eg. map is decoded into a list of maps)
-var decoded = map[string]interface{}{
+// In case of HCL it's slightly different from Viper's internal representation
+// (e.g. map is decoded into a list of maps).
+var decoded = map[string]any{
 	"key": "value",
-	"list": []interface{}{
+	"list": []any{
 		"item1",
 		"item2",
 		"item3",
 	},
-	"map": []map[string]interface{}{
+	"map": []map[string]any{
 		{
 			"key": "value",
 		},
 	},
-	"nested_map": []map[string]interface{}{
+	"nested_map": []map[string]any{
 		{
-			"map": []map[string]interface{}{
+			"map": []map[string]any{
 				{
 					"key": "value",
-					"list": []interface{}{
+					"list": []any{
 						"item1",
 						"item2",
 						"item3",
@@ -73,21 +75,21 @@ var decoded = map[string]interface{}{
 	},
 }

-// Viper's internal representation
-var data = map[string]interface{}{
+// data is Viper's internal representation.
+var data = map[string]any{
 	"key": "value",
-	"list": []interface{}{
+	"list": []any{
 		"item1",
 		"item2",
 		"item3",
 	},
-	"map": map[string]interface{}{
+	"map": map[string]any{
 		"key": "value",
 	},
-	"nested_map": map[string]interface{}{
-		"map": map[string]interface{}{
+	"nested_map": map[string]any{
+		"map": map[string]any{
 			"key": "value",
-			"list": []interface{}{
+			"list": []any{
 				"item1",
 				"item2",
 				"item3",
@@ -100,40 +102,30 @@ func TestCodec_Encode(t *testing.T) {
 	codec := Codec{}

 	b, err := codec.Encode(data)
-	if err != nil {
-		t.Fatal(err)
-	}
+	require.NoError(t, err)

-	if encoded != string(b) {
-		t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", string(b), encoded)
-	}
+	assert.Equal(t, encoded, string(b))
 }

 func TestCodec_Decode(t *testing.T) {
 	t.Run("OK", func(t *testing.T) {
 		codec := Codec{}

-		v := map[string]interface{}{}
+		v := map[string]any{}

 		err := codec.Decode([]byte(original), v)
-		if err != nil {
-			t.Fatal(err)
-		}
+		require.NoError(t, err)

-		if !reflect.DeepEqual(decoded, v) {
-			t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", v, decoded)
-		}
+		assert.Equal(t, decoded, v)
 	})

 	t.Run("InvalidData", func(t *testing.T) {
 		codec := Codec{}

-		v := map[string]interface{}{}
+		v := map[string]any{}

 		err := codec.Decode([]byte(`invalid data`), v)
-		if err == nil {
-			t.Fatal("expected decoding to fail")
-		}
+		require.Error(t, err)

 		t.Logf("decoding failed as expected: %s", err)
 	})
@@ -19,11 +19,11 @@ type Codec struct {
 	LoadOptions  LoadOptions
 }

-func (c Codec) Encode(v map[string]interface{}) ([]byte, error) {
+func (c Codec) Encode(v map[string]any) ([]byte, error) {
 	cfg := ini.Empty()
 	ini.PrettyFormat = false

-	flattened := map[string]interface{}{}
+	flattened := map[string]any{}

 	flattened = flattenAndMergeMap(flattened, v, "", c.keyDelimiter())

@@ -62,7 +62,7 @@ func (c Codec) Encode(v map[string]interface{}) ([]byte, error) {
 	return buf.Bytes(), nil
 }

-func (c Codec) Decode(b []byte, v map[string]interface{}) error {
+func (c Codec) Decode(b []byte, v map[string]any) error {
 	cfg := ini.Empty(c.LoadOptions)

 	err := cfg.Append(b)
@@ -1,11 +1,13 @@
 package ini

 import (
-	"reflect"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )

-// original form of the data
+// original form of the data.
 const original = `; key-value pair
 key=value ; key-value pair

@@ -15,30 +17,30 @@ key=%(key)s

 `

-// encoded form of the data
+// encoded form of the data.
 const encoded = `key=value

 [map]
 key=value
 `

-// decoded form of the data
+// decoded form of the data.
 //
-// in case of INI it's slightly different from Viper's internal representation
-// (eg. top level keys land in a section called default)
-var decoded = map[string]interface{}{
-	"DEFAULT": map[string]interface{}{
+// In case of INI it's slightly different from Viper's internal representation
+// (e.g. top level keys land in a section called default).
+var decoded = map[string]any{
+	"DEFAULT": map[string]any{
 		"key": "value",
 	},
-	"map": map[string]interface{}{
+	"map": map[string]any{
 		"key": "value",
 	},
 }

-// Viper's internal representation
-var data = map[string]interface{}{
+// data is Viper's internal representation.
+var data = map[string]any{
 	"key": "value",
-	"map": map[string]interface{}{
+	"map": map[string]any{
 		"key": "value",
 	},
 }
@@ -48,35 +50,27 @@ func TestCodec_Encode(t *testing.T) {
 		codec := Codec{}

 		b, err := codec.Encode(data)
-		if err != nil {
-			t.Fatal(err)
-		}
+		require.NoError(t, err)

-		if encoded != string(b) {
-			t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", string(b), encoded)
-		}
+		assert.Equal(t, encoded, string(b))
 	})

 	t.Run("Default", func(t *testing.T) {
 		codec := Codec{}

-		data := map[string]interface{}{
-			"default": map[string]interface{}{
+		data := map[string]any{
+			"default": map[string]any{
 				"key": "value",
 			},
-			"map": map[string]interface{}{
+			"map": map[string]any{
 				"key": "value",
 			},
 		}

 		b, err := codec.Encode(data)
-		if err != nil {
-			t.Fatal(err)
-		}
+		require.NoError(t, err)

-		if encoded != string(b) {
-			t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", string(b), encoded)
-		}
+		assert.Equal(t, encoded, string(b))
 	})
 }

@@ -84,27 +78,21 @@ func TestCodec_Decode(t *testing.T) {
 	t.Run("OK", func(t *testing.T) {
 		codec := Codec{}

-		v := map[string]interface{}{}
+		v := map[string]any{}

 		err := codec.Decode([]byte(original), v)
-		if err != nil {
-			t.Fatal(err)
-		}
+		require.NoError(t, err)

-		if !reflect.DeepEqual(decoded, v) {
-			t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", v, decoded)
-		}
+		assert.Equal(t, decoded, v)
 	})

 	t.Run("InvalidData", func(t *testing.T) {
 		codec := Codec{}

-		v := map[string]interface{}{}
+		v := map[string]any{}

 		err := codec.Decode([]byte(`invalid data`), v)
-		if err == nil {
-			t.Fatal("expected decoding to fail")
-		}
+		require.Error(t, err)

 		t.Logf("decoding failed as expected: %s", err)
 	})
@@ -15,22 +15,22 @@ import (
 // In case intermediate keys do not exist, or map to a non-map value,
 // a new map is created and inserted, and the search continues from there:
 // the initial map "m" may be modified!
-func deepSearch(m map[string]interface{}, path []string) map[string]interface{} {
+func deepSearch(m map[string]any, path []string) map[string]any {
 	for _, k := range path {
 		m2, ok := m[k]
 		if !ok {
 			// intermediate key does not exist
 			// => create it and continue from there
-			m3 := make(map[string]interface{})
+			m3 := make(map[string]any)
 			m[k] = m3
 			m = m3
 			continue
 		}
-		m3, ok := m2.(map[string]interface{})
+		m3, ok := m2.(map[string]any)
 		if !ok {
 			// intermediate key is a value
 			// => replace with a new map
-			m3 = make(map[string]interface{})
+			m3 = make(map[string]any)
 			m[k] = m3
 		}
 		// continue search from here
@@ -40,27 +40,27 @@ func deepSearch(m map[string]interface{}, path []string) map[string]interface{}
 }

 // flattenAndMergeMap recursively flattens the given map into a new map
-// Code is based on the function with the same name in tha main package.
-// TODO: move it to a common place
-func flattenAndMergeMap(shadow map[string]interface{}, m map[string]interface{}, prefix string, delimiter string) map[string]interface{} {
+// Code is based on the function with the same name in the main package.
+// TODO: move it to a common place.
+func flattenAndMergeMap(shadow, m map[string]any, prefix, delimiter string) map[string]any {
 	if shadow != nil && prefix != "" && shadow[prefix] != nil {
 		// prefix is shadowed => nothing more to flatten
 		return shadow
 	}
 	if shadow == nil {
-		shadow = make(map[string]interface{})
+		shadow = make(map[string]any)
 	}

-	var m2 map[string]interface{}
+	var m2 map[string]any
 	if prefix != "" {
 		prefix += delimiter
 	}
 	for k, val := range m {
 		fullKey := prefix + k
-		switch val.(type) {
-		case map[string]interface{}:
-			m2 = val.(map[string]interface{})
-		case map[interface{}]interface{}:
+		switch val := val.(type) {
+		case map[string]any:
+			m2 = val
+		case map[any]any:
 			m2 = cast.ToStringMap(val)
 		default:
 			// immediate value
@@ -20,12 +20,12 @@ type Codec struct {
 	Properties *properties.Properties
 }

-func (c *Codec) Encode(v map[string]interface{}) ([]byte, error) {
+func (c *Codec) Encode(v map[string]any) ([]byte, error) {
 	if c.Properties == nil {
 		c.Properties = properties.NewProperties()
 	}

-	flattened := map[string]interface{}{}
+	flattened := map[string]any{}

 	flattened = flattenAndMergeMap(flattened, v, "", c.keyDelimiter())

@@ -54,7 +54,7 @@ func (c *Codec) Encode(v map[string]interface{}) ([]byte, error) {
 	return buf.Bytes(), nil
 }

-func (c *Codec) Decode(b []byte, v map[string]interface{}) error {
+func (c *Codec) Decode(b []byte, v map[string]any) error {
 	var err error
 	c.Properties, err = properties.Load(b, properties.UTF8)
 	if err != nil {
@@ -1,25 +1,27 @@
 package javaproperties

 import (
-	"reflect"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )

-// original form of the data
+// original form of the data.
 const original = `#key-value pair
 key = value
 map.key = value
 `

-// encoded form of the data
+// encoded form of the data.
 const encoded = `key = value
 map.key = value
 `

-// Viper's internal representation
-var data = map[string]interface{}{
+// data is Viper's internal representation.
+var data = map[string]any{
 	"key": "value",
-	"map": map[string]interface{}{
+	"map": map[string]any{
 		"key": "value",
 	},
 }
@@ -28,29 +30,21 @@ func TestCodec_Encode(t *testing.T) {
 	codec := Codec{}

 	b, err := codec.Encode(data)
-	if err != nil {
-		t.Fatal(err)
-	}
+	require.NoError(t, err)

-	if encoded != string(b) {
-		t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", string(b), encoded)
-	}
+	assert.Equal(t, encoded, string(b))
 }

 func TestCodec_Decode(t *testing.T) {
 	t.Run("OK", func(t *testing.T) {
 		codec := Codec{}

-		v := map[string]interface{}{}
+		v := map[string]any{}

 		err := codec.Decode([]byte(original), v)
-		if err != nil {
-			t.Fatal(err)
-		}
+		require.NoError(t, err)

-		if !reflect.DeepEqual(data, v) {
-			t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", v, data)
-		}
+		assert.Equal(t, data, v)
 	})

 	t.Run("InvalidData", func(t *testing.T) {
@@ -58,32 +52,24 @@ func TestCodec_Decode(t *testing.T) {

 		codec := Codec{}

-		v := map[string]interface{}{}
+		v := map[string]any{}

 		codec.Decode([]byte(``), v)

-		if len(v) > 0 {
-			t.Fatalf("expected map to be empty when data is invalid\nactual: %#v", v)
-		}
+		assert.Empty(t, v)
 	})
 }

 func TestCodec_DecodeEncode(t *testing.T) {
 	codec := Codec{}

-	v := map[string]interface{}{}
+	v := map[string]any{}

 	err := codec.Decode([]byte(original), v)
-	if err != nil {
-		t.Fatal(err)
-	}
+	require.NoError(t, err)

 	b, err := codec.Encode(data)
-	if err != nil {
-		t.Fatal(err)
-	}
+	require.NoError(t, err)

-	if original != string(b) {
-		t.Fatalf("encoded value does not match the original\nactual:   %#v\nexpected: %#v", string(b), original)
-	}
+	assert.Equal(t, original, string(b))
 }
@@ -15,22 +15,22 @@ import (
 // In case intermediate keys do not exist, or map to a non-map value,
 // a new map is created and inserted, and the search continues from there:
 // the initial map "m" may be modified!
-func deepSearch(m map[string]interface{}, path []string) map[string]interface{} {
+func deepSearch(m map[string]any, path []string) map[string]any {
 	for _, k := range path {
 		m2, ok := m[k]
 		if !ok {
 			// intermediate key does not exist
 			// => create it and continue from there
-			m3 := make(map[string]interface{})
+			m3 := make(map[string]any)
 			m[k] = m3
 			m = m3
 			continue
 		}
-		m3, ok := m2.(map[string]interface{})
+		m3, ok := m2.(map[string]any)
 		if !ok {
 			// intermediate key is a value
 			// => replace with a new map
-			m3 = make(map[string]interface{})
+			m3 = make(map[string]any)
 			m[k] = m3
 		}
 		// continue search from here
@@ -40,27 +40,27 @@ func deepSearch(m map[string]interface{}, path []string) map[string]interface{}
 }

 // flattenAndMergeMap recursively flattens the given map into a new map
-// Code is based on the function with the same name in tha main package.
-// TODO: move it to a common place
-func flattenAndMergeMap(shadow map[string]interface{}, m map[string]interface{}, prefix string, delimiter string) map[string]interface{} {
+// Code is based on the function with the same name in the main package.
+// TODO: move it to a common place.
+func flattenAndMergeMap(shadow, m map[string]any, prefix, delimiter string) map[string]any {
 	if shadow != nil && prefix != "" && shadow[prefix] != nil {
 		// prefix is shadowed => nothing more to flatten
 		return shadow
 	}
 	if shadow == nil {
-		shadow = make(map[string]interface{})
+		shadow = make(map[string]any)
 	}

-	var m2 map[string]interface{}
+	var m2 map[string]any
 	if prefix != "" {
 		prefix += delimiter
 	}
 	for k, val := range m {
 		fullKey := prefix + k
-		switch val.(type) {
-		case map[string]interface{}:
-			m2 = val.(map[string]interface{})
-		case map[interface{}]interface{}:
+		switch val := val.(type) {
+		case map[string]any:
+			m2 = val
+		case map[any]any:
 			m2 = cast.ToStringMap(val)
 		default:
 			// immediate value
@@ -7,11 +7,11 @@ import (
 // Codec implements the encoding.Encoder and encoding.Decoder interfaces for JSON encoding.
 type Codec struct{}

-func (Codec) Encode(v map[string]interface{}) ([]byte, error) {
+func (Codec) Encode(v map[string]any) ([]byte, error) {
 	// TODO: expose prefix and indent in the Codec as setting?
 	return json.MarshalIndent(v, "", "  ")
 }

-func (Codec) Decode(b []byte, v map[string]interface{}) error {
+func (Codec) Decode(b []byte, v map[string]any) error {
 	return json.Unmarshal(b, &v)
 }
@@ -1,11 +1,13 @@
 package json

 import (
-	"reflect"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )

-// encoded form of the data
+// encoded form of the data.
 const encoded = `{
  "key": "value",
  "list": [
@@ -28,21 +30,21 @@ const encoded = `{
  }
 }`

-// Viper's internal representation
-var data = map[string]interface{}{
+// data is Viper's internal representation.
+var data = map[string]any{
 	"key": "value",
-	"list": []interface{}{
+	"list": []any{
 		"item1",
 		"item2",
 		"item3",
 	},
-	"map": map[string]interface{}{
+	"map": map[string]any{
 		"key": "value",
 	},
-	"nested_map": map[string]interface{}{
-		"map": map[string]interface{}{
+	"nested_map": map[string]any{
+		"map": map[string]any{
 			"key": "value",
-			"list": []interface{}{
+			"list": []any{
 				"item1",
 				"item2",
 				"item3",
@@ -55,40 +57,30 @@ func TestCodec_Encode(t *testing.T) {
 	codec := Codec{}

 	b, err := codec.Encode(data)
-	if err != nil {
-		t.Fatal(err)
-	}
+	require.NoError(t, err)

-	if encoded != string(b) {
-		t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", string(b), encoded)
-	}
+	assert.Equal(t, encoded, string(b))
 }

 func TestCodec_Decode(t *testing.T) {
 	t.Run("OK", func(t *testing.T) {
 		codec := Codec{}

-		v := map[string]interface{}{}
+		v := map[string]any{}

 		err := codec.Decode([]byte(encoded), v)
-		if err != nil {
-			t.Fatal(err)
-		}
+		require.NoError(t, err)

-		if !reflect.DeepEqual(data, v) {
-			t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", v, data)
-		}
+		assert.Equal(t, data, v)
 	})

 	t.Run("InvalidData", func(t *testing.T) {
 		codec := Codec{}

-		v := map[string]interface{}{}
+		v := map[string]any{}

 		err := codec.Decode([]byte(`invalid data`), v)
-		if err == nil {
-			t.Fatal("expected decoding to fail")
-		}
+		require.Error(t, err)

 		t.Logf("decoding failed as expected: %s", err)
 	})
@@ -7,10 +7,10 @@ import (
 // Codec implements the encoding.Encoder and encoding.Decoder interfaces for TOML encoding.
 type Codec struct{}

-func (Codec) Encode(v map[string]interface{}) ([]byte, error) {
+func (Codec) Encode(v map[string]any) ([]byte, error) {
 	return toml.Marshal(v)
 }

-func (Codec) Decode(b []byte, v map[string]interface{}) error {
+func (Codec) Decode(b []byte, v map[string]any) error {
 	return toml.Unmarshal(b, &v)
 }
@@ -1,11 +1,13 @@
 package toml

 import (
-	"reflect"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )

-// original form of the data
+// original form of the data.
 const original = `# key-value pair
 key = "value"
 list = ["item1", "item2", "item3"]
@@ -25,7 +27,7 @@ list = [
 ]
 `

-// encoded form of the data
+// encoded form of the data.
 const encoded = `key = 'value'
 list = ['item1', 'item2', 'item3']

@@ -38,21 +40,21 @@ key = 'value'
 list = ['item1', 'item2', 'item3']
 `

-// Viper's internal representation
-var data = map[string]interface{}{
+// data is Viper's internal representation.
+var data = map[string]any{
 	"key": "value",
-	"list": []interface{}{
+	"list": []any{
 		"item1",
 		"item2",
 		"item3",
 	},
-	"map": map[string]interface{}{
+	"map": map[string]any{
 		"key": "value",
 	},
-	"nested_map": map[string]interface{}{
-		"map": map[string]interface{}{
+	"nested_map": map[string]any{
+		"map": map[string]any{
 			"key": "value",
-			"list": []interface{}{
+			"list": []any{
 				"item1",
 				"item2",
 				"item3",
@@ -65,40 +67,30 @@ func TestCodec_Encode(t *testing.T) {
 	codec := Codec{}

 	b, err := codec.Encode(data)
-	if err != nil {
-		t.Fatal(err)
-	}
+	require.NoError(t, err)

-	if encoded != string(b) {
-		t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", string(b), encoded)
-	}
+	assert.Equal(t, encoded, string(b))
 }

 func TestCodec_Decode(t *testing.T) {
 	t.Run("OK", func(t *testing.T) {
 		codec := Codec{}

-		v := map[string]interface{}{}
+		v := map[string]any{}

 		err := codec.Decode([]byte(original), v)
-		if err != nil {
-			t.Fatal(err)
-		}
+		require.NoError(t, err)

-		if !reflect.DeepEqual(data, v) {
-			t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", v, data)
-		}
+		assert.Equal(t, data, v)
 	})

 	t.Run("InvalidData", func(t *testing.T) {
 		codec := Codec{}

-		v := map[string]interface{}{}
+		v := map[string]any{}

 		err := codec.Decode([]byte(`invalid data`), v)
-		if err == nil {
-			t.Fatal("expected decoding to fail")
-		}
+		require.Error(t, err)

 		t.Logf("decoding failed as expected: %s", err)
 	})
@@ -5,10 +5,10 @@ import "gopkg.in/yaml.v3"
 // Codec implements the encoding.Encoder and encoding.Decoder interfaces for YAML encoding.
 type Codec struct{}

-func (Codec) Encode(v map[string]interface{}) ([]byte, error) {
+func (Codec) Encode(v map[string]any) ([]byte, error) {
 	return yaml.Marshal(v)
 }

-func (Codec) Decode(b []byte, v map[string]interface{}) error {
+func (Codec) Decode(b []byte, v map[string]any) error {
 	return yaml.Unmarshal(b, &v)
 }
@@ -1,11 +1,13 @@
 package yaml

 import (
-	"reflect"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )

-// original form of the data
+// original form of the data.
 const original = `# key-value pair
 key: value
 list:
@@ -26,7 +28,7 @@ nested_map:
            - item3
 `

-// encoded form of the data
+// encoded form of the data.
 const encoded = `key: value
 list:
    - item1
@@ -43,24 +45,24 @@ nested_map:
            - item3
 `

-// decoded form of the data
+// decoded form of the data.
 //
-// in case of YAML it's slightly different from Viper's internal representation
-// (eg. map is decoded into a map with interface key)
-var decoded = map[string]interface{}{
+// In case of YAML it's slightly different from Viper's internal representation
+// (e.g. map is decoded into a map with interface key).
+var decoded = map[string]any{
 	"key": "value",
-	"list": []interface{}{
+	"list": []any{
 		"item1",
 		"item2",
 		"item3",
 	},
-	"map": map[string]interface{}{
+	"map": map[string]any{
 		"key": "value",
 	},
-	"nested_map": map[string]interface{}{
-		"map": map[string]interface{}{
+	"nested_map": map[string]any{
+		"map": map[string]any{
 			"key": "value",
-			"list": []interface{}{
+			"list": []any{
 				"item1",
 				"item2",
 				"item3",
@@ -69,21 +71,21 @@ var decoded = map[string]interface{}{
 	},
 }

-// Viper's internal representation
-var data = map[string]interface{}{
+// data is Viper's internal representation.
+var data = map[string]any{
 	"key": "value",
-	"list": []interface{}{
+	"list": []any{
 		"item1",
 		"item2",
 		"item3",
 	},
-	"map": map[string]interface{}{
+	"map": map[string]any{
 		"key": "value",
 	},
-	"nested_map": map[string]interface{}{
-		"map": map[string]interface{}{
+	"nested_map": map[string]any{
+		"map": map[string]any{
 			"key": "value",
-			"list": []interface{}{
+			"list": []any{
 				"item1",
 				"item2",
 				"item3",
@@ -96,40 +98,30 @@ func TestCodec_Encode(t *testing.T) {
 	codec := Codec{}

 	b, err := codec.Encode(data)
-	if err != nil {
-		t.Fatal(err)
-	}
+	require.NoError(t, err)

-	if encoded != string(b) {
-		t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", string(b), encoded)
-	}
+	assert.Equal(t, encoded, string(b))
 }

 func TestCodec_Decode(t *testing.T) {
 	t.Run("OK", func(t *testing.T) {
 		codec := Codec{}

-		v := map[string]interface{}{}
+		v := map[string]any{}

 		err := codec.Decode([]byte(original), v)
-		if err != nil {
-			t.Fatal(err)
-		}
+		require.NoError(t, err)

-		if !reflect.DeepEqual(decoded, v) {
-			t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", v, decoded)
-		}
+		assert.Equal(t, decoded, v)
 	})

 	t.Run("InvalidData", func(t *testing.T) {
 		codec := Codec{}

-		v := map[string]interface{}{}
+		v := map[string]any{}

 		err := codec.Decode([]byte(`invalid data`), v)
-		if err == nil {
-			t.Fatal("expected decoding to fail")
-		}
+		require.Error(t, err)

 		t.Logf("decoding failed as expected: %s", err)
 	})
@@ -0,0 +1,5 @@
+//go:build viper_bind_struct
+
+package features
+
+const BindStruct = true
@@ -0,0 +1,5 @@
+//go:build !viper_bind_struct
+
+package features
+
+const BindStruct = false
@@ -1,40 +0,0 @@
-//go:build !go1.17
-// +build !go1.17
-
-package testutil
-
-import (
-	"os"
-	"testing"
-)
-
-// Based on https://github.com/frankban/quicktest/blob/577841610793d24f99e31cc2c0ef3a541fefd7c7/patch.go#L34-L64
-// Licensed under the MIT license
-// Copyright (c) 2017 Canonical Ltd.
-
-// Setenv sets an environment variable to a temporary value for the
-// duration of the test.
-//
-// At the end of the test (see "Deferred execution" in the package docs), the
-// environment variable is returned to its original value.
-func Setenv(t *testing.T, name, val string) {
-	setenv(t, name, val, true)
-}
-
-// setenv sets or unsets an environment variable to a temporary value for the
-// duration of the test
-func setenv(t *testing.T, name, val string, valOK bool) {
-	oldVal, oldOK := os.LookupEnv(name)
-	if valOK {
-		os.Setenv(name, val)
-	} else {
-		os.Unsetenv(name)
-	}
-	t.Cleanup(func() {
-		if oldOK {
-			os.Setenv(name, oldVal)
-		} else {
-			os.Unsetenv(name)
-		}
-	})
-}
@@ -1,18 +0,0 @@
-//go:build go1.17
-// +build go1.17
-
-package testutil
-
-import (
-	"testing"
-)
-
-// Setenv sets an environment variable to a temporary value for the
-// duration of the test.
-//
-// This shim can be removed once support for Go <1.17 is dropped.
-func Setenv(t *testing.T, name, val string) {
-	t.Helper()
-
-	t.Setenv(name, val)
-}
@@ -1,77 +1,68 @@
 package viper

 import (
-	"fmt"
+	"context"

-	jww "github.com/spf13/jwalterweatherman"
+	slog "github.com/sagikazarmark/slog-shim"
 )

 // Logger is a unified interface for various logging use cases and practices, including:
 //   - leveled logging
 //   - structured logging
+//
+// Deprecated: use `log/slog` instead.
 type Logger interface {
 	// Trace logs a Trace event.
 	//
 	// Even more fine-grained information than Debug events.
 	// Loggers not supporting this level should fall back to Debug.
-	Trace(msg string, keyvals ...interface{})
+	Trace(msg string, keyvals ...any)

 	// Debug logs a Debug event.
 	//
 	// A verbose series of information events.
 	// They are useful when debugging the system.
-	Debug(msg string, keyvals ...interface{})
+	Debug(msg string, keyvals ...any)

 	// Info logs an Info event.
 	//
 	// General information about what's happening inside the system.
-	Info(msg string, keyvals ...interface{})
+	Info(msg string, keyvals ...any)

 	// Warn logs a Warn(ing) event.
 	//
 	// Non-critical events that should be looked at.
-	Warn(msg string, keyvals ...interface{})
+	Warn(msg string, keyvals ...any)

 	// Error logs an Error event.
 	//
 	// Critical events that require immediate attention.
 	// Loggers commonly provide Fatal and Panic levels above Error level,
-	// but exiting and panicing is out of scope for a logging library.
-	Error(msg string, keyvals ...interface{})
+	// but exiting and panicking is out of scope for a logging library.
+	Error(msg string, keyvals ...any)
 }

-type jwwLogger struct{}
-
-func (jwwLogger) Trace(msg string, keyvals ...interface{}) {
-	jww.TRACE.Printf(jwwLogMessage(msg, keyvals...))
+// WithLogger sets a custom logger.
+func WithLogger(l *slog.Logger) Option {
+	return optionFunc(func(v *Viper) {
+		v.logger = l
+	})
 }

-func (jwwLogger) Debug(msg string, keyvals ...interface{}) {
-	jww.DEBUG.Printf(jwwLogMessage(msg, keyvals...))
+type discardHandler struct{}
+
+func (n *discardHandler) Enabled(_ context.Context, _ slog.Level) bool {
+	return false
 }

-func (jwwLogger) Info(msg string, keyvals ...interface{}) {
-	jww.INFO.Printf(jwwLogMessage(msg, keyvals...))
+func (n *discardHandler) Handle(_ context.Context, _ slog.Record) error {
+	return nil
 }

-func (jwwLogger) Warn(msg string, keyvals ...interface{}) {
-	jww.WARN.Printf(jwwLogMessage(msg, keyvals...))
+func (n *discardHandler) WithAttrs(_ []slog.Attr) slog.Handler {
+	return n
 }

-func (jwwLogger) Error(msg string, keyvals ...interface{}) {
-	jww.ERROR.Printf(jwwLogMessage(msg, keyvals...))
-}
-
-func jwwLogMessage(msg string, keyvals ...interface{}) string {
-	out := msg
-
-	if len(keyvals) > 0 && len(keyvals)%2 == 1 {
-		keyvals = append(keyvals, nil)
-	}
-
-	for i := 0; i <= len(keyvals)-2; i += 2 {
-		out = fmt.Sprintf("%s %v=%v", out, keyvals[i], keyvals[i+1])
-	}
-
-	return out
+func (n *discardHandler) WithGroup(_ string) slog.Handler {
+	return n
 }
@@ -1,7 +1,6 @@
 package viper

 import (
-	"fmt"
 	"strings"
 	"testing"

@@ -46,11 +45,11 @@ func TestNestedOverrides(t *testing.T) {
 	deepCheckValue(assert, v, overrideLayer, []string{"tom", "size"}, 4)

 	// Case 4: key:value overridden by a map
-	v = overrideDefault(assert, "tom.size", 4, "tom", map[string]interface{}{"age": 10}) // "tom.size" is first given "4" as default value, then "tom" is overridden by map{"age":10}
-	assert.Equal(4, v.Get("tom.size"))                                                   // "tom.size" should still be reachable
-	assert.Equal(10, v.Get("tom.age"))                                                   // new value should be there
-	deepCheckValue(assert, v, overrideLayer, []string{"tom", "age"}, 10)                 // new value should be there
-	v = override(assert, "tom.size", 4, "tom", map[string]interface{}{"age": 10})
+	v = overrideDefault(assert, "tom.size", 4, "tom", map[string]any{"age": 10}) // "tom.size" is first given "4" as default value, then "tom" is overridden by map{"age":10}
+	assert.Equal(4, v.Get("tom.size"))                                           // "tom.size" should still be reachable
+	assert.Equal(10, v.Get("tom.age"))                                           // new value should be there
+	deepCheckValue(assert, v, overrideLayer, []string{"tom", "age"}, 10)         // new value should be there
+	v = override(assert, "tom.size", 4, "tom", map[string]any{"age": 10})
 	assert.Nil(v.Get("tom.size"))
 	assert.Equal(10, v.Get("tom.age"))
 	deepCheckValue(assert, v, overrideLayer, []string{"tom", "age"}, 10)
@@ -75,11 +74,11 @@ func TestNestedOverrides(t *testing.T) {
 	}
 }

-func overrideDefault(assert *assert.Assertions, firstPath string, firstValue interface{}, secondPath string, secondValue interface{}) *Viper {
+func overrideDefault(assert *assert.Assertions, firstPath string, firstValue any, secondPath string, secondValue any) *Viper {
 	return overrideFromLayer(defaultLayer, assert, firstPath, firstValue, secondPath, secondValue)
 }

-func override(assert *assert.Assertions, firstPath string, firstValue interface{}, secondPath string, secondValue interface{}) *Viper {
+func override(assert *assert.Assertions, firstPath string, firstValue any, secondPath string, secondValue any) *Viper {
 	return overrideFromLayer(overrideLayer, assert, firstPath, firstValue, secondPath, secondValue)
 }

@@ -94,11 +93,11 @@ func override(assert *assert.Assertions, firstPath string, firstValue interface{
 //
 // After each assignment, the value is checked, retrieved both by its full path
 // and by its key sequence (successive maps).
-func overrideFromLayer(l layer, assert *assert.Assertions, firstPath string, firstValue interface{}, secondPath string, secondValue interface{}) *Viper {
+func overrideFromLayer(l layer, assert *assert.Assertions, firstPath string, firstValue any, secondPath string, secondValue any) *Viper {
 	v := New()
 	firstKeys := strings.Split(firstPath, v.keyDelim)
 	if assert == nil ||
-		len(firstKeys) == 0 || len(firstKeys[0]) == 0 {
+		len(firstKeys) == 0 || firstKeys[0] == "" {
 		return v
 	}

@@ -116,7 +115,7 @@ func overrideFromLayer(l layer, assert *assert.Assertions, firstPath string, fir

 	// Override and check new value
 	secondKeys := strings.Split(secondPath, v.keyDelim)
-	if len(secondKeys) == 0 || len(secondKeys[0]) == 0 {
+	if len(secondKeys) == 0 || secondKeys[0] == "" {
 		return v
 	}
 	v.Set(secondPath, secondValue)
@@ -127,15 +126,15 @@ func overrideFromLayer(l layer, assert *assert.Assertions, firstPath string, fir
 }

 // deepCheckValue checks that all given keys correspond to a valid path in the
-// configuration map of the given layer, and that the final value equals the one given
-func deepCheckValue(assert *assert.Assertions, v *Viper, l layer, keys []string, value interface{}) {
+// configuration map of the given layer, and that the final value equals the one given.
+func deepCheckValue(assert *assert.Assertions, v *Viper, l layer, keys []string, value any) {
 	if assert == nil || v == nil ||
-		len(keys) == 0 || len(keys[0]) == 0 {
+		len(keys) == 0 || keys[0] == "" {
 		return
 	}

 	// init
-	var val interface{}
+	var val any
 	var ms string
 	switch l {
 	case defaultLayer:
@@ -147,28 +146,25 @@ func deepCheckValue(assert *assert.Assertions, v *Viper, l layer, keys []string,
 	}

 	// loop through map
-	var m map[string]interface{}
-	err := false
+	var m map[string]any
 	for _, k := range keys {
 		if val == nil {
-			assert.Fail(fmt.Sprintf("%s is not a map[string]interface{}", ms))
+			assert.Failf("%s is not a map[string]any", ms)
 			return
 		}

 		// deep scan of the map to get the final value
-		switch val.(type) {
-		case map[interface{}]interface{}:
+		switch val := val.(type) {
+		case map[any]any:
 			m = cast.ToStringMap(val)
-		case map[string]interface{}:
-			m = val.(map[string]interface{})
+		case map[string]any:
+			m = val
 		default:
-			assert.Fail(fmt.Sprintf("%s is not a map[string]interface{}", ms))
+			assert.Failf("%s is not a map[string]any", ms)
 			return
 		}
 		ms = ms + "[\"" + k + "\"]"
 		val = m[k]
 	}
-	if !err {
-		assert.Equal(value, val)
-	}
+	assert.Equal(value, val)
 }
@@ -91,6 +91,8 @@ func getConfigManager(rp viper.RemoteProvider) (crypt.ConfigManager, error) {
 			cm, err = crypt.NewEtcdV3ConfigManager(endpoints, kr)
 		case "firestore":
 			cm, err = crypt.NewFirestoreConfigManager(endpoints, kr)
+		case "nats":
+			cm, err = crypt.NewNatsConfigManager(endpoints, kr)
 		default:
 			cm, err = crypt.NewConsulConfigManager(endpoints, kr)
 		}
@@ -102,6 +104,8 @@ func getConfigManager(rp viper.RemoteProvider) (crypt.ConfigManager, error) {
 			cm, err = crypt.NewStandardEtcdV3ConfigManager(endpoints)
 		case "firestore":
 			cm, err = crypt.NewStandardFirestoreConfigManager(endpoints)
+		case "nats":
+			cm, err = crypt.NewStandardNatsConfigManager(endpoints)
 		default:
 			cm, err = crypt.NewStandardConsulConfigManager(endpoints)
 		}
@@ -18,6 +18,7 @@ import (
 	"strings"
 	"unicode"

+	slog "github.com/sagikazarmark/slog-shim"
 	"github.com/spf13/cast"
 )

@@ -38,11 +39,11 @@ func (pe ConfigParseError) Unwrap() error {

 // toCaseInsensitiveValue checks if the value is a  map;
 // if so, create a copy and lower-case the keys recursively.
-func toCaseInsensitiveValue(value interface{}) interface{} {
+func toCaseInsensitiveValue(value any) any {
 	switch v := value.(type) {
-	case map[interface{}]interface{}:
+	case map[any]any:
 		value = copyAndInsensitiviseMap(cast.ToStringMap(v))
-	case map[string]interface{}:
+	case map[string]any:
 		value = copyAndInsensitiviseMap(v)
 	}

@@ -51,15 +52,15 @@ func toCaseInsensitiveValue(value interface{}) interface{} {

 // copyAndInsensitiviseMap behaves like insensitiviseMap, but creates a copy of
 // any map it makes case insensitive.
-func copyAndInsensitiviseMap(m map[string]interface{}) map[string]interface{} {
-	nm := make(map[string]interface{})
+func copyAndInsensitiviseMap(m map[string]any) map[string]any {
+	nm := make(map[string]any)

 	for key, val := range m {
 		lkey := strings.ToLower(key)
 		switch v := val.(type) {
-		case map[interface{}]interface{}:
+		case map[any]any:
 			nm[lkey] = copyAndInsensitiviseMap(cast.ToStringMap(v))
-		case map[string]interface{}:
+		case map[string]any:
 			nm[lkey] = copyAndInsensitiviseMap(v)
 		default:
 			nm[lkey] = v
@@ -69,23 +70,23 @@ func copyAndInsensitiviseMap(m map[string]interface{}) map[string]interface{} {
 	return nm
 }

-func insensitiviseVal(val interface{}) interface{} {
-	switch val.(type) {
-	case map[interface{}]interface{}:
+func insensitiviseVal(val any) any {
+	switch v := val.(type) {
+	case map[any]any:
 		// nested map: cast and recursively insensitivise
 		val = cast.ToStringMap(val)
-		insensitiviseMap(val.(map[string]interface{}))
-	case map[string]interface{}:
+		insensitiviseMap(val.(map[string]any))
+	case map[string]any:
 		// nested map: recursively insensitivise
-		insensitiviseMap(val.(map[string]interface{}))
-	case []interface{}:
+		insensitiviseMap(v)
+	case []any:
 		// nested array: recursively insensitivise
-		insensitiveArray(val.([]interface{}))
+		insensitiveArray(v)
 	}
 	return val
 }

-func insensitiviseMap(m map[string]interface{}) {
+func insensitiviseMap(m map[string]any) {
 	for key, val := range m {
 		val = insensitiviseVal(val)
 		lower := strings.ToLower(key)
@@ -98,13 +99,13 @@ func insensitiviseMap(m map[string]interface{}) {
 	}
 }

-func insensitiveArray(a []interface{}) {
+func insensitiveArray(a []any) {
 	for i, val := range a {
 		a[i] = insensitiviseVal(val)
 	}
 }

-func absPathify(logger Logger, inPath string) string {
+func absPathify(logger *slog.Logger, inPath string) string {
 	logger.Info("trying to resolve absolute path", "path", inPath)

 	if inPath == "$HOME" || strings.HasPrefix(inPath, "$HOME"+string(os.PathSeparator)) {
@@ -155,7 +156,7 @@ func safeMul(a, b uint) uint {
 	return c
 }

-// parseSizeInBytes converts strings like 1GB or 12 mb into an unsigned integer number of bytes
+// parseSizeInBytes converts strings like 1GB or 12 mb into an unsigned integer number of bytes.
 func parseSizeInBytes(sizeStr string) uint {
 	sizeStr = strings.TrimSpace(sizeStr)
 	lastChar := len(sizeStr) - 1
@@ -197,22 +198,22 @@ func parseSizeInBytes(sizeStr string) uint {
 // In case intermediate keys do not exist, or map to a non-map value,
 // a new map is created and inserted, and the search continues from there:
 // the initial map "m" may be modified!
-func deepSearch(m map[string]interface{}, path []string) map[string]interface{} {
+func deepSearch(m map[string]any, path []string) map[string]any {
 	for _, k := range path {
 		m2, ok := m[k]
 		if !ok {
 			// intermediate key does not exist
 			// => create it and continue from there
-			m3 := make(map[string]interface{})
+			m3 := make(map[string]any)
 			m[k] = m3
 			m = m3
 			continue
 		}
-		m3, ok := m2.(map[string]interface{})
+		m3, ok := m2.(map[string]any)
 		if !ok {
 			// intermediate key is a value
 			// => replace with a new map
-			m3 = make(map[string]interface{})
+			m3 = make(map[string]any)
 			m[k] = m3
 		}
 		// continue search from here
@@ -13,24 +13,24 @@ package viper
 import (
 	"os"
 	"path/filepath"
-	"reflect"
 	"testing"

-	"github.com/spf13/viper/internal/testutil"
+	slog "github.com/sagikazarmark/slog-shim"
+	"github.com/stretchr/testify/assert"
 )

 func TestCopyAndInsensitiviseMap(t *testing.T) {
 	var (
-		given = map[string]interface{}{
+		given = map[string]any{
 			"Foo": 32,
-			"Bar": map[interface{}]interface{}{
+			"Bar": map[any]any{
 				"ABc": "A",
 				"cDE": "B",
 			},
 		}
-		expected = map[string]interface{}{
+		expected = map[string]any{
 			"foo": 32,
-			"bar": map[string]interface{}{
+			"bar": map[string]any{
 				"abc": "A",
 				"cde": "B",
 			},
@@ -39,22 +39,15 @@ func TestCopyAndInsensitiviseMap(t *testing.T) {

 	got := copyAndInsensitiviseMap(given)

-	if !reflect.DeepEqual(got, expected) {
-		t.Fatalf("Got %q\nexpected\n%q", got, expected)
-	}
+	assert.Equal(t, expected, got)
+	_, ok := given["foo"]
+	assert.False(t, ok)
+	_, ok = given["bar"]
+	assert.False(t, ok)

-	if _, ok := given["foo"]; ok {
-		t.Fatal("Input map changed")
-	}
-
-	if _, ok := given["bar"]; ok {
-		t.Fatal("Input map changed")
-	}
-
-	m := given["Bar"].(map[interface{}]interface{})
-	if _, ok := m["ABc"]; !ok {
-		t.Fatal("Input map changed")
-	}
+	m := given["Bar"].(map[any]any)
+	_, ok = m["ABc"]
+	assert.True(t, ok)
 }

 func TestAbsPathify(t *testing.T) {
@@ -64,8 +57,8 @@ func TestAbsPathify(t *testing.T) {
 	homer := filepath.Join(home, "homer")
 	wd, _ := os.Getwd()

-	testutil.Setenv(t, "HOMER_ABSOLUTE_PATH", homer)
-	testutil.Setenv(t, "VAR_WITH_RELATIVE_PATH", "relative")
+	t.Setenv("HOMER_ABSOLUTE_PATH", homer)
+	t.Setenv("VAR_WITH_RELATIVE_PATH", "relative")

 	tests := []struct {
 		input  string
@@ -87,9 +80,7 @@ func TestAbsPathify(t *testing.T) {
 	}

 	for _, test := range tests {
-		got := absPathify(jwwLogger{}, test.input)
-		if got != test.output {
-			t.Errorf("Got %v\nexpected\n%q", got, test.output)
-		}
+		got := absPathify(slog.Default(), test.input)
+		assert.Equal(t, test.output, got)
 	}
 }
@@ -35,6 +35,7 @@ import (

 	"github.com/fsnotify/fsnotify"
 	"github.com/mitchellh/mapstructure"
+	slog "github.com/sagikazarmark/slog-shim"
 	"github.com/spf13/afero"
 	"github.com/spf13/cast"
 	"github.com/spf13/pflag"
@@ -47,6 +48,7 @@ import (
 	"github.com/spf13/viper/internal/encoding/json"
 	"github.com/spf13/viper/internal/encoding/toml"
 	"github.com/spf13/viper/internal/encoding/yaml"
+	"github.com/spf13/viper/internal/features"
 )

 // ConfigMarshalError happens when failing to marshal the configuration.
@@ -76,7 +78,7 @@ type remoteConfigFactory interface {
 	WatchChannel(rp RemoteProvider) (<-chan *RemoteResponse, chan bool)
 }

-// RemoteConfig is optional, see the remote package
+// RemoteConfig is optional, see the remote package.
 var RemoteConfig remoteConfigFactory

 // UnsupportedConfigError denotes encountering an unsupported
@@ -101,7 +103,7 @@ func (str UnsupportedRemoteProviderError) Error() string {
 // pull the configuration from the remote provider.
 type RemoteConfigError string

-// Error returns the formatted remote provider error
+// Error returns the formatted remote provider error.
 func (rce RemoteConfigError) Error() string {
 	return fmt.Sprintf("Remote Configurations Error: %s", string(rce))
 }
@@ -125,7 +127,7 @@ func (faee ConfigFileAlreadyExistsError) Error() string {
 }

 // A DecoderConfigOption can be passed to viper.Unmarshal to configure
-// mapstructure.DecoderConfig options
+// mapstructure.DecoderConfig options.
 type DecoderConfigOption func(*mapstructure.DecoderConfig)

 // DecodeHook returns a DecoderConfigOption which overrides the default
@@ -206,10 +208,10 @@ type Viper struct {
 	allowEmptyEnv       bool

 	parents        []string
-	config         map[string]interface{}
-	override       map[string]interface{}
-	defaults       map[string]interface{}
-	kvstore        map[string]interface{}
+	config         map[string]any
+	override       map[string]any
+	defaults       map[string]any
+	kvstore        map[string]any
 	pflags         map[string]FlagValue
 	env            map[string][]string
 	aliases        map[string]string
@@ -217,7 +219,7 @@ type Viper struct {

 	onConfigChange func(fsnotify.Event)

-	logger Logger
+	logger *slog.Logger

 	// TODO: should probably be protected with a mutex
 	encoderRegistry *encoding.EncoderRegistry
@@ -231,16 +233,16 @@ func New() *Viper {
 	v.configName = "config"
 	v.configPermissions = os.FileMode(0o644)
 	v.fs = afero.NewOsFs()
-	v.config = make(map[string]interface{})
+	v.config = make(map[string]any)
 	v.parents = []string{}
-	v.override = make(map[string]interface{})
-	v.defaults = make(map[string]interface{})
-	v.kvstore = make(map[string]interface{})
+	v.override = make(map[string]any)
+	v.defaults = make(map[string]any)
+	v.kvstore = make(map[string]any)
 	v.pflags = make(map[string]FlagValue)
 	v.env = make(map[string][]string)
 	v.aliases = make(map[string]string)
 	v.typeByDefValue = false
-	v.logger = jwwLogger{}
+	v.logger = slog.New(&discardHandler{})

 	v.resetEncoding()

@@ -301,10 +303,10 @@ func NewWithOptions(opts ...Option) *Viper {
 func Reset() {
 	v = New()
 	SupportedExts = []string{"json", "toml", "yaml", "yml", "properties", "props", "prop", "hcl", "tfvars", "dotenv", "env", "ini"}
-	SupportedRemoteProviders = []string{"etcd", "etcd3", "consul", "firestore"}
+	SupportedRemoteProviders = []string{"etcd", "etcd3", "consul", "firestore", "nats"}
 }

-// TODO: make this lazy initialization instead
+// TODO: make this lazy initialization instead.
 func (v *Viper) resetEncoding() {
 	encoderRegistry := encoding.NewEncoderRegistry()
 	decoderRegistry := encoding.NewDecoderRegistry()
@@ -420,7 +422,7 @@ type RemoteProvider interface {
 var SupportedExts = []string{"json", "toml", "yaml", "yml", "properties", "props", "prop", "hcl", "tfvars", "dotenv", "env", "ini"}

 // SupportedRemoteProviders are universally supported remote providers.
-var SupportedRemoteProviders = []string{"etcd", "etcd3", "consul", "firestore"}
+var SupportedRemoteProviders = []string{"etcd", "etcd3", "consul", "firestore", "nats"}

 // OnConfigChange sets the event handler that is called when a config file changes.
 func OnConfigChange(run func(in fsnotify.Event)) { v.OnConfigChange(run) }
@@ -438,7 +440,7 @@ func (v *Viper) WatchConfig() {
 	initWG := sync.WaitGroup{}
 	initWG.Add(1)
 	go func() {
-		watcher, err := newWatcher()
+		watcher, err := fsnotify.NewWatcher()
 		if err != nil {
 			v.logger.Error(fmt.Sprintf("failed to create watcher: %s", err))
 			os.Exit(1)
@@ -523,6 +525,12 @@ func (v *Viper) SetEnvPrefix(in string) {
 	}
 }

+func GetEnvPrefix() string { return v.GetEnvPrefix() }
+
+func (v *Viper) GetEnvPrefix() string {
+	return v.envPrefix
+}
+
 func (v *Viper) mergeWithEnvPrefix(in string) string {
 	if v.envPrefix != "" {
 		return strings.ToUpper(v.envPrefix + "_" + in)
@@ -578,12 +586,12 @@ func (v *Viper) AddConfigPath(in string) {

 // AddRemoteProvider adds a remote configuration source.
 // Remote Providers are searched in the order they are added.
-// provider is a string value: "etcd", "etcd3", "consul" or "firestore" are currently supported.
-// endpoint is the url.  etcd requires http://ip:port  consul requires ip:port
+// provider is a string value: "etcd", "etcd3", "consul", "firestore" or "nats" are currently supported.
+// endpoint is the url.  etcd requires http://ip:port, consul requires ip:port, nats requires nats://ip:port
 // path is the path in the k/v store to retrieve configuration
 // To retrieve a config file called myapp.json from /configs/myapp.json
 // you should set path to /configs and set config name (SetConfigName()) to
-// "myapp"
+// "myapp".
 func AddRemoteProvider(provider, endpoint, path string) error {
 	return v.AddRemoteProvider(provider, endpoint, path)
 }
@@ -609,14 +617,14 @@ func (v *Viper) AddRemoteProvider(provider, endpoint, path string) error {

 // AddSecureRemoteProvider adds a remote configuration source.
 // Secure Remote Providers are searched in the order they are added.
-// provider is a string value: "etcd", "etcd3", "consul" or "firestore" are currently supported.
+// provider is a string value: "etcd", "etcd3", "consul", "firestore" or "nats" are currently supported.
 // endpoint is the url.  etcd requires http://ip:port  consul requires ip:port
 // secretkeyring is the filepath to your openpgp secret keyring.  e.g. /etc/secrets/myring.gpg
 // path is the path in the k/v store to retrieve configuration
 // To retrieve a config file called myapp.json from /configs/myapp.json
 // you should set path to /configs and set config name (SetConfigName()) to
-// "myapp"
-// Secure Remote Providers are implemented with github.com/bketelsen/crypt
+// "myapp".
+// Secure Remote Providers are implemented with github.com/bketelsen/crypt.
 func AddSecureRemoteProvider(provider, endpoint, path, secretkeyring string) error {
 	return v.AddSecureRemoteProvider(provider, endpoint, path, secretkeyring)
 }
@@ -653,7 +661,7 @@ func (v *Viper) providerPathExists(p *defaultRemoteProvider) bool {
 // searchMap recursively searches for a value for path in source map.
 // Returns nil if not found.
 // Note: This assumes that the path entries and map keys are lower cased.
-func (v *Viper) searchMap(source map[string]interface{}, path []string) interface{} {
+func (v *Viper) searchMap(source map[string]any, path []string) any {
 	if len(path) == 0 {
 		return source
 	}
@@ -666,13 +674,13 @@ func (v *Viper) searchMap(source map[string]interface{}, path []string) interfac
 		}

 		// Nested case
-		switch next.(type) {
-		case map[interface{}]interface{}:
+		switch next := next.(type) {
+		case map[any]any:
 			return v.searchMap(cast.ToStringMap(next), path[1:])
-		case map[string]interface{}:
+		case map[string]any:
 			// Type assertion is safe here since it is only reached
 			// if the type of `next` is the same as the type being asserted
-			return v.searchMap(next.(map[string]interface{}), path[1:])
+			return v.searchMap(next, path[1:])
 		default:
 			// got a value but nested key expected, return "nil" for not found
 			return nil
@@ -692,7 +700,7 @@ func (v *Viper) searchMap(source map[string]interface{}, path []string) interfac
 // in their keys).
 //
 // Note: This assumes that the path entries and map keys are lower cased.
-func (v *Viper) searchIndexableWithPathPrefixes(source interface{}, path []string) interface{} {
+func (v *Viper) searchIndexableWithPathPrefixes(source any, path []string) any {
 	if len(path) == 0 {
 		return source
 	}
@@ -701,11 +709,11 @@ func (v *Viper) searchIndexableWithPathPrefixes(source interface{}, path []strin
 	for i := len(path); i > 0; i-- {
 		prefixKey := strings.ToLower(strings.Join(path[0:i], v.keyDelim))

-		var val interface{}
+		var val any
 		switch sourceIndexable := source.(type) {
-		case []interface{}:
+		case []any:
 			val = v.searchSliceWithPathPrefixes(sourceIndexable, prefixKey, i, path)
-		case map[string]interface{}:
+		case map[string]any:
 			val = v.searchMapWithPathPrefixes(sourceIndexable, prefixKey, i, path)
 		}
 		if val != nil {
@@ -722,11 +730,11 @@ func (v *Viper) searchIndexableWithPathPrefixes(source interface{}, path []strin
 // This function is part of the searchIndexableWithPathPrefixes recurring search and
 // should not be called directly from functions other than searchIndexableWithPathPrefixes.
 func (v *Viper) searchSliceWithPathPrefixes(
-	sourceSlice []interface{},
+	sourceSlice []any,
 	prefixKey string,
 	pathIndex int,
 	path []string,
-) interface{} {
+) any {
 	// if the prefixKey is not a number or it is out of bounds of the slice
 	index, err := strconv.Atoi(prefixKey)
 	if err != nil || len(sourceSlice) <= index {
@@ -741,9 +749,9 @@ func (v *Viper) searchSliceWithPathPrefixes(
 	}

 	switch n := next.(type) {
-	case map[interface{}]interface{}:
+	case map[any]any:
 		return v.searchIndexableWithPathPrefixes(cast.ToStringMap(n), path[pathIndex:])
-	case map[string]interface{}, []interface{}:
+	case map[string]any, []any:
 		return v.searchIndexableWithPathPrefixes(n, path[pathIndex:])
 	default:
 		// got a value but nested key expected, do nothing and look for next prefix
@@ -758,11 +766,11 @@ func (v *Viper) searchSliceWithPathPrefixes(
 // This function is part of the searchIndexableWithPathPrefixes recurring search and
 // should not be called directly from functions other than searchIndexableWithPathPrefixes.
 func (v *Viper) searchMapWithPathPrefixes(
-	sourceMap map[string]interface{},
+	sourceMap map[string]any,
 	prefixKey string,
 	pathIndex int,
 	path []string,
-) interface{} {
+) any {
 	next, ok := sourceMap[prefixKey]
 	if !ok {
 		return nil
@@ -775,9 +783,9 @@ func (v *Viper) searchMapWithPathPrefixes(

 	// Nested case
 	switch n := next.(type) {
-	case map[interface{}]interface{}:
+	case map[any]any:
 		return v.searchIndexableWithPathPrefixes(cast.ToStringMap(n), path[pathIndex:])
-	case map[string]interface{}, []interface{}:
+	case map[string]any, []any:
 		return v.searchIndexableWithPathPrefixes(n, path[pathIndex:])
 	default:
 		// got a value but nested key expected, do nothing and look for next prefix
@@ -792,8 +800,8 @@ func (v *Viper) searchMapWithPathPrefixes(
 // e.g., if "foo.bar" has a value in the given map, it “shadows”
 //
 //	"foo.bar.baz" in a lower-priority map
-func (v *Viper) isPathShadowedInDeepMap(path []string, m map[string]interface{}) string {
-	var parentVal interface{}
+func (v *Viper) isPathShadowedInDeepMap(path []string, m map[string]any) string {
+	var parentVal any
 	for i := 1; i < len(path); i++ {
 		parentVal = v.searchMap(m, path[0:i])
 		if parentVal == nil {
@@ -801,9 +809,9 @@ func (v *Viper) isPathShadowedInDeepMap(path []string, m map[string]interface{})
 			return ""
 		}
 		switch parentVal.(type) {
-		case map[interface{}]interface{}:
+		case map[any]any:
 			continue
-		case map[string]interface{}:
+		case map[string]any:
 			continue
 		default:
 			// parentVal is a regular value which shadows "path"
@@ -818,12 +826,14 @@ func (v *Viper) isPathShadowedInDeepMap(path []string, m map[string]interface{})
 // e.g., if "foo.bar" has a value in the given map, it “shadows”
 //
 //	"foo.bar.baz" in a lower-priority map
-func (v *Viper) isPathShadowedInFlatMap(path []string, mi interface{}) string {
+func (v *Viper) isPathShadowedInFlatMap(path []string, mi any) string {
 	// unify input map
 	var m map[string]interface{}
-	switch mi.(type) {
-	case map[string]string, map[string]FlagValue:
-		m = cast.ToStringMap(mi)
+	switch miv := mi.(type) {
+	case map[string]string:
+		m = castMapStringToMapInterface(miv)
+	case map[string]FlagValue:
+		m = castMapFlagToMapInterface(miv)
 	default:
 		return ""
 	}
@@ -887,9 +897,9 @@ func GetViper() *Viper {
 // override, flag, env, config file, key/value store, default
 //
 // Get returns an interface. For a specific value use one of the Get____ methods.
-func Get(key string) interface{} { return v.Get(key) }
+func Get(key string) any { return v.Get(key) }

-func (v *Viper) Get(key string) interface{} {
+func (v *Viper) Get(key string) any {
 	lcaseKey := strings.ToLower(key)
 	val := v.find(lcaseKey, true)
 	if val == nil {
@@ -950,7 +960,8 @@ func (v *Viper) Sub(key string) *Viper {
 	}

 	if reflect.TypeOf(data).Kind() == reflect.Map {
-		subv.parents = append(v.parents, strings.ToLower(key))
+		subv.parents = append([]string(nil), v.parents...)
+		subv.parents = append(subv.parents, strings.ToLower(key))
 		subv.automaticEnvApplied = v.automaticEnvApplied
 		subv.envPrefix = v.envPrefix
 		subv.envKeyReplacer = v.envKeyReplacer
@@ -1059,9 +1070,9 @@ func (v *Viper) GetStringSlice(key string) []string {
 }

 // GetStringMap returns the value associated with the key as a map of interfaces.
-func GetStringMap(key string) map[string]interface{} { return v.GetStringMap(key) }
+func GetStringMap(key string) map[string]any { return v.GetStringMap(key) }

-func (v *Viper) GetStringMap(key string) map[string]interface{} {
+func (v *Viper) GetStringMap(key string) map[string]any {
 	return cast.ToStringMap(v.Get(key))
 }

@@ -1089,27 +1100,58 @@ func (v *Viper) GetSizeInBytes(key string) uint {
 }

 // UnmarshalKey takes a single key and unmarshals it into a Struct.
-func UnmarshalKey(key string, rawVal interface{}, opts ...DecoderConfigOption) error {
+func UnmarshalKey(key string, rawVal any, opts ...DecoderConfigOption) error {
 	return v.UnmarshalKey(key, rawVal, opts...)
 }

-func (v *Viper) UnmarshalKey(key string, rawVal interface{}, opts ...DecoderConfigOption) error {
+func (v *Viper) UnmarshalKey(key string, rawVal any, opts ...DecoderConfigOption) error {
 	return decode(v.Get(key), defaultDecoderConfig(rawVal, opts...))
 }

 // Unmarshal unmarshals the config into a Struct. Make sure that the tags
 // on the fields of the structure are properly set.
-func Unmarshal(rawVal interface{}, opts ...DecoderConfigOption) error {
+func Unmarshal(rawVal any, opts ...DecoderConfigOption) error {
 	return v.Unmarshal(rawVal, opts...)
 }

-func (v *Viper) Unmarshal(rawVal interface{}, opts ...DecoderConfigOption) error {
-	return decode(v.AllSettings(), defaultDecoderConfig(rawVal, opts...))
+func (v *Viper) Unmarshal(rawVal any, opts ...DecoderConfigOption) error {
+	keys := v.AllKeys()
+
+	if features.BindStruct {
+		// TODO: make this optional?
+		structKeys, err := v.decodeStructKeys(rawVal, opts...)
+		if err != nil {
+			return err
+		}
+
+		keys = append(keys, structKeys...)
+	}
+
+	// TODO: struct keys should be enough?
+	return decode(v.getSettings(keys), defaultDecoderConfig(rawVal, opts...))
+}
+
+func (v *Viper) decodeStructKeys(input any, opts ...DecoderConfigOption) ([]string, error) {
+	var structKeyMap map[string]any
+
+	err := decode(input, defaultDecoderConfig(&structKeyMap, opts...))
+	if err != nil {
+		return nil, err
+	}
+
+	flattenedStructKeyMap := v.flattenAndMergeMap(map[string]bool{}, structKeyMap, "")
+
+	r := make([]string, 0, len(flattenedStructKeyMap))
+	for v := range flattenedStructKeyMap {
+		r = append(r, v)
+	}
+
+	return r, nil
 }

 // defaultDecoderConfig returns default mapstructure.DecoderConfig with support
-// of time.Duration values & string slices
-func defaultDecoderConfig(output interface{}, opts ...DecoderConfigOption) *mapstructure.DecoderConfig {
+// of time.Duration values & string slices.
+func defaultDecoderConfig(output any, opts ...DecoderConfigOption) *mapstructure.DecoderConfig {
 	c := &mapstructure.DecoderConfig{
 		Metadata:         nil,
 		Result:           output,
@@ -1125,8 +1167,8 @@ func defaultDecoderConfig(output interface{}, opts ...DecoderConfigOption) *maps
 	return c
 }

-// A wrapper around mapstructure.Decode that mimics the WeakDecode functionality
-func decode(input interface{}, config *mapstructure.DecoderConfig) error {
+// decode is a wrapper around mapstructure.Decode that mimics the WeakDecode functionality.
+func decode(input any, config *mapstructure.DecoderConfig) error {
 	decoder, err := mapstructure.NewDecoder(config)
 	if err != nil {
 		return err
@@ -1136,15 +1178,28 @@ func decode(input interface{}, config *mapstructure.DecoderConfig) error {

 // UnmarshalExact unmarshals the config into a Struct, erroring if a field is nonexistent
 // in the destination struct.
-func UnmarshalExact(rawVal interface{}, opts ...DecoderConfigOption) error {
+func UnmarshalExact(rawVal any, opts ...DecoderConfigOption) error {
 	return v.UnmarshalExact(rawVal, opts...)
 }

-func (v *Viper) UnmarshalExact(rawVal interface{}, opts ...DecoderConfigOption) error {
+func (v *Viper) UnmarshalExact(rawVal any, opts ...DecoderConfigOption) error {
 	config := defaultDecoderConfig(rawVal, opts...)
 	config.ErrorUnused = true

-	return decode(v.AllSettings(), config)
+	keys := v.AllKeys()
+
+	if features.BindStruct {
+		// TODO: make this optional?
+		structKeys, err := v.decodeStructKeys(rawVal, opts...)
+		if err != nil {
+			return err
+		}
+
+		keys = append(keys, structKeys...)
+	}
+
+	// TODO: struct keys should be enough?
+	return decode(v.getSettings(keys), config)
 }

 // BindPFlags binds a full flag set to the configuration, using each flag's long
@@ -1237,9 +1292,9 @@ func (v *Viper) MustBindEnv(input ...string) {
 // corresponds to a flag, the flag's default value is returned.
 //
 // Note: this assumes a lower-cased key given.
-func (v *Viper) find(lcaseKey string, flagDefault bool) interface{} {
+func (v *Viper) find(lcaseKey string, flagDefault bool) any {
 	var (
-		val    interface{}
+		val    any
 		exists bool
 		path   = strings.Split(lcaseKey, v.keyDelim)
 		nested = len(path) > 1
@@ -1398,46 +1453,46 @@ func readAsCSV(val string) ([]string, error) {
 }

 // mostly copied from pflag's implementation of this operation here https://github.com/spf13/pflag/blob/master/string_to_string.go#L79
-// alterations are: errors are swallowed, map[string]interface{} is returned in order to enable cast.ToStringMap
-func stringToStringConv(val string) interface{} {
+// alterations are: errors are swallowed, map[string]any is returned in order to enable cast.ToStringMap.
+func stringToStringConv(val string) any {
 	val = strings.Trim(val, "[]")
 	// An empty string would cause an empty map
-	if len(val) == 0 {
-		return map[string]interface{}{}
+	if val == "" {
+		return map[string]any{}
 	}
 	r := csv.NewReader(strings.NewReader(val))
 	ss, err := r.Read()
 	if err != nil {
 		return nil
 	}
-	out := make(map[string]interface{}, len(ss))
+	out := make(map[string]any, len(ss))
 	for _, pair := range ss {
-		kv := strings.SplitN(pair, "=", 2)
-		if len(kv) != 2 {
+		k, vv, found := strings.Cut(pair, "=")
+		if !found {
 			return nil
 		}
-		out[kv[0]] = kv[1]
+		out[k] = vv
 	}
 	return out
 }

 // mostly copied from pflag's implementation of this operation here https://github.com/spf13/pflag/blob/d5e0c0615acee7028e1e2740a11102313be88de1/string_to_int.go#L68
-// alterations are: errors are swallowed, map[string]interface{} is returned in order to enable cast.ToStringMap
-func stringToIntConv(val string) interface{} {
+// alterations are: errors are swallowed, map[string]any is returned in order to enable cast.ToStringMap.
+func stringToIntConv(val string) any {
 	val = strings.Trim(val, "[]")
 	// An empty string would cause an empty map
-	if len(val) == 0 {
-		return map[string]interface{}{}
+	if val == "" {
+		return map[string]any{}
 	}
 	ss := strings.Split(val, ",")
-	out := make(map[string]interface{}, len(ss))
+	out := make(map[string]any, len(ss))
 	for _, pair := range ss {
-		kv := strings.SplitN(pair, "=", 2)
-		if len(kv) != 2 {
+		k, vv, found := strings.Cut(pair, "=")
+		if !found {
 			return nil
 		}
 		var err error
-		out[kv[0]], err = strconv.Atoi(kv[1])
+		out[k], err = strconv.Atoi(vv)
 		if err != nil {
 			return nil
 		}
@@ -1474,13 +1529,13 @@ func (v *Viper) SetEnvKeyReplacer(r *strings.Replacer) {

 // RegisterAlias creates an alias that provides another accessor for the same key.
 // This enables one to change a name without breaking the application.
-func RegisterAlias(alias string, key string) { v.RegisterAlias(alias, key) }
+func RegisterAlias(alias, key string) { v.RegisterAlias(alias, key) }

-func (v *Viper) RegisterAlias(alias string, key string) {
+func (v *Viper) RegisterAlias(alias, key string) {
 	v.registerAlias(alias, strings.ToLower(key))
 }

-func (v *Viper) registerAlias(alias string, key string) {
+func (v *Viper) registerAlias(alias, key string) {
 	alias = strings.ToLower(alias)
 	if alias != key && alias != v.realKey(key) {
 		_, exists := v.aliases[alias]
@@ -1538,9 +1593,9 @@ func (v *Viper) InConfig(key string) bool {
 // SetDefault sets the default value for this key.
 // SetDefault is case-insensitive for a key.
 // Default only used when no value is provided by the user via flag, config or ENV.
-func SetDefault(key string, value interface{}) { v.SetDefault(key, value) }
+func SetDefault(key string, value any) { v.SetDefault(key, value) }

-func (v *Viper) SetDefault(key string, value interface{}) {
+func (v *Viper) SetDefault(key string, value any) {
 	// If alias passed in, then set the proper default
 	key = v.realKey(strings.ToLower(key))
 	value = toCaseInsensitiveValue(value)
@@ -1557,9 +1612,9 @@ func (v *Viper) SetDefault(key string, value interface{}) {
 // Set is case-insensitive for a key.
 // Will be used instead of values obtained via
 // flags, config file, ENV, default, or key/value store.
-func Set(key string, value interface{}) { v.Set(key, value) }
+func Set(key string, value any) { v.Set(key, value) }

-func (v *Viper) Set(key string, value interface{}) {
+func (v *Viper) Set(key string, value any) {
 	// If alias passed in, then set the proper override
 	key = v.realKey(strings.ToLower(key))
 	value = toCaseInsensitiveValue(value)
@@ -1593,7 +1648,7 @@ func (v *Viper) ReadInConfig() error {
 		return err
 	}

-	config := make(map[string]interface{})
+	config := make(map[string]any)

 	err = v.unmarshalReader(bytes.NewReader(file), config)
 	if err != nil {
@@ -1631,7 +1686,7 @@ func (v *Viper) MergeInConfig() error {
 func ReadConfig(in io.Reader) error { return v.ReadConfig(in) }

 func (v *Viper) ReadConfig(in io.Reader) error {
-	v.config = make(map[string]interface{})
+	v.config = make(map[string]any)
 	return v.unmarshalReader(in, v.config)
 }

@@ -1639,7 +1694,7 @@ func (v *Viper) ReadConfig(in io.Reader) error {
 func MergeConfig(in io.Reader) error { return v.MergeConfig(in) }

 func (v *Viper) MergeConfig(in io.Reader) error {
-	cfg := make(map[string]interface{})
+	cfg := make(map[string]any)
 	if err := v.unmarshalReader(in, cfg); err != nil {
 		return err
 	}
@@ -1648,11 +1703,11 @@ func (v *Viper) MergeConfig(in io.Reader) error {

 // MergeConfigMap merges the configuration from the map given with an existing config.
 // Note that the map given may be modified.
-func MergeConfigMap(cfg map[string]interface{}) error { return v.MergeConfigMap(cfg) }
+func MergeConfigMap(cfg map[string]any) error { return v.MergeConfigMap(cfg) }

-func (v *Viper) MergeConfigMap(cfg map[string]interface{}) error {
+func (v *Viper) MergeConfigMap(cfg map[string]any) error {
 	if v.config == nil {
-		v.config = make(map[string]interface{})
+		v.config = make(map[string]any)
 	}
 	insensitiviseMap(cfg)
 	mergeMaps(cfg, v.config, nil)
@@ -1717,7 +1772,7 @@ func (v *Viper) writeConfig(filename string, force bool) error {
 		return UnsupportedConfigError(configType)
 	}
 	if v.config == nil {
-		v.config = make(map[string]interface{})
+		v.config = make(map[string]any)
 	}
 	flags := os.O_CREATE | os.O_TRUNC | os.O_WRONLY
 	if !force {
@@ -1736,13 +1791,7 @@ func (v *Viper) writeConfig(filename string, force bool) error {
 	return f.Sync()
 }

-// Unmarshal a Reader into a map.
-// Should probably be an unexported function.
-func unmarshalReader(in io.Reader, c map[string]interface{}) error {
-	return v.unmarshalReader(in, c)
-}
-
-func (v *Viper) unmarshalReader(in io.Reader, c map[string]interface{}) error {
+func (v *Viper) unmarshalReader(in io.Reader, c map[string]any) error {
 	buf := new(bytes.Buffer)
 	buf.ReadFrom(in)

@@ -1776,7 +1825,7 @@ func (v *Viper) marshalWriter(f afero.File, configType string) error {
 	return nil
 }

-func keyExists(k string, m map[string]interface{}) string {
+func keyExists(k string, m map[string]any) string {
 	lk := strings.ToLower(k)
 	for mk := range m {
 		lmk := strings.ToLower(mk)
@@ -1788,33 +1837,33 @@ func keyExists(k string, m map[string]interface{}) string {
 }

 func castToMapStringInterface(
-	src map[interface{}]interface{},
-) map[string]interface{} {
-	tgt := map[string]interface{}{}
+	src map[any]any,
+) map[string]any {
+	tgt := map[string]any{}
 	for k, v := range src {
 		tgt[fmt.Sprintf("%v", k)] = v
 	}
 	return tgt
 }

-func castMapStringSliceToMapInterface(src map[string][]string) map[string]interface{} {
-	tgt := map[string]interface{}{}
+func castMapStringSliceToMapInterface(src map[string][]string) map[string]any {
+	tgt := map[string]any{}
 	for k, v := range src {
 		tgt[k] = v
 	}
 	return tgt
 }

-func castMapStringToMapInterface(src map[string]string) map[string]interface{} {
-	tgt := map[string]interface{}{}
+func castMapStringToMapInterface(src map[string]string) map[string]any {
+	tgt := map[string]any{}
 	for k, v := range src {
 		tgt[k] = v
 	}
 	return tgt
 }

-func castMapFlagToMapInterface(src map[string]FlagValue) map[string]interface{} {
-	tgt := map[string]interface{}{}
+func castMapFlagToMapInterface(src map[string]FlagValue) map[string]any {
+	tgt := map[string]any{}
 	for k, v := range src {
 		tgt[k] = v
 	}
@@ -1822,17 +1871,15 @@ func castMapFlagToMapInterface(src map[string]FlagValue) map[string]interface{}
 }

 // mergeMaps merges two maps. The `itgt` parameter is for handling go-yaml's
-// insistence on parsing nested structures as `map[interface{}]interface{}`
+// insistence on parsing nested structures as `map[any]any`
 // instead of using a `string` as the key for nest structures beyond one level
 // deep. Both map types are supported as there is a go-yaml fork that uses
-// `map[string]interface{}` instead.
-func mergeMaps(
-	src, tgt map[string]interface{}, itgt map[interface{}]interface{},
-) {
+// `map[string]any` instead.
+func mergeMaps(src, tgt map[string]any, itgt map[any]any) {
 	for sk, sv := range src {
 		tk := keyExists(sk, tgt)
 		if tk == "" {
-			v.logger.Trace("", "tk", "\"\"", fmt.Sprintf("tgt[%s]", sk), sv)
+			v.logger.Debug("", "tk", "\"\"", fmt.Sprintf("tgt[%s]", sk), sv)
 			tgt[sk] = sv
 			if itgt != nil {
 				itgt[sk] = sv
@@ -1842,7 +1889,7 @@ func mergeMaps(

 		tv, ok := tgt[tk]
 		if !ok {
-			v.logger.Trace("", fmt.Sprintf("ok[%s]", tk), false, fmt.Sprintf("tgt[%s]", sk), sv)
+			v.logger.Debug("", fmt.Sprintf("ok[%s]", tk), false, fmt.Sprintf("tgt[%s]", sk), sv)
 			tgt[sk] = sv
 			if itgt != nil {
 				itgt[sk] = sv
@@ -1853,7 +1900,7 @@ func mergeMaps(
 		svType := reflect.TypeOf(sv)
 		tvType := reflect.TypeOf(tv)

-		v.logger.Trace(
+		v.logger.Debug(
 			"processing",
 			"key", sk,
 			"st", svType,
@@ -1863,12 +1910,12 @@ func mergeMaps(
 		)

 		switch ttv := tv.(type) {
-		case map[interface{}]interface{}:
-			v.logger.Trace("merging maps (must convert)")
-			tsv, ok := sv.(map[interface{}]interface{})
+		case map[any]any:
+			v.logger.Debug("merging maps (must convert)")
+			tsv, ok := sv.(map[any]any)
 			if !ok {
 				v.logger.Error(
-					"Could not cast sv to map[interface{}]interface{}",
+					"Could not cast sv to map[any]any",
 					"key", sk,
 					"st", svType,
 					"tt", tvType,
@@ -1881,12 +1928,12 @@ func mergeMaps(
 			ssv := castToMapStringInterface(tsv)
 			stv := castToMapStringInterface(ttv)
 			mergeMaps(ssv, stv, ttv)
-		case map[string]interface{}:
-			v.logger.Trace("merging maps")
-			tsv, ok := sv.(map[string]interface{})
+		case map[string]any:
+			v.logger.Debug("merging maps")
+			tsv, ok := sv.(map[string]any)
 			if !ok {
 				v.logger.Error(
-					"Could not cast sv to map[string]interface{}",
+					"Could not cast sv to map[string]any",
 					"key", sk,
 					"st", svType,
 					"tt", tvType,
@@ -1897,7 +1944,7 @@ func mergeMaps(
 			}
 			mergeMaps(tsv, ttv, nil)
 		default:
-			v.logger.Trace("setting value")
+			v.logger.Debug("setting value")
 			tgt[tk] = sv
 			if itgt != nil {
 				itgt[tk] = sv
@@ -1948,7 +1995,7 @@ func (v *Viper) getKeyValueConfig() error {
 	return RemoteConfigError("No Files Found")
 }

-func (v *Viper) getRemoteConfig(provider RemoteProvider) (map[string]interface{}, error) {
+func (v *Viper) getRemoteConfig(provider RemoteProvider) (map[string]any, error) {
 	reader, err := RemoteConfig.Get(provider)
 	if err != nil {
 		return nil, err
@@ -1997,7 +2044,7 @@ func (v *Viper) watchKeyValueConfig() error {
 	return RemoteConfigError("No Files Found")
 }

-func (v *Viper) watchRemoteConfig(provider RemoteProvider) (map[string]interface{}, error) {
+func (v *Viper) watchRemoteConfig(provider RemoteProvider) (map[string]any, error) {
 	reader, err := RemoteConfig.Watch(provider)
 	if err != nil {
 		return nil, err
@@ -2007,7 +2054,7 @@ func (v *Viper) watchRemoteConfig(provider RemoteProvider) (map[string]interface
 }

 // AllKeys returns all keys holding a value, regardless of where they are set.
-// Nested keys are returned with a v.keyDelim separator
+// Nested keys are returned with a v.keyDelim separator.
 func AllKeys() []string { return v.AllKeys() }

 func (v *Viper) AllKeys() []string {
@@ -2036,7 +2083,7 @@ func (v *Viper) AllKeys() []string {
 //     it is skipped.
 //
 // The resulting set of paths is merged to the given shadow set at the same time.
-func (v *Viper) flattenAndMergeMap(shadow map[string]bool, m map[string]interface{}, prefix string) map[string]bool {
+func (v *Viper) flattenAndMergeMap(shadow map[string]bool, m map[string]any, prefix string) map[string]bool {
 	if shadow != nil && prefix != "" && shadow[prefix] {
 		// prefix is shadowed => nothing more to flatten
 		return shadow
@@ -2045,16 +2092,16 @@ func (v *Viper) flattenAndMergeMap(shadow map[string]bool, m map[string]interfac
 		shadow = make(map[string]bool)
 	}

-	var m2 map[string]interface{}
+	var m2 map[string]any
 	if prefix != "" {
 		prefix += v.keyDelim
 	}
 	for k, val := range m {
 		fullKey := prefix + k
-		switch val.(type) {
-		case map[string]interface{}:
-			m2 = val.(map[string]interface{})
-		case map[interface{}]interface{}:
+		switch val := val.(type) {
+		case map[string]any:
+			m2 = val
+		case map[any]any:
 			m2 = cast.ToStringMap(val)
 		default:
 			// immediate value
@@ -2069,7 +2116,7 @@ func (v *Viper) flattenAndMergeMap(shadow map[string]bool, m map[string]interfac

 // mergeFlatMap merges the given maps, excluding values of the second map
 // shadowed by values from the first map.
-func (v *Viper) mergeFlatMap(shadow map[string]bool, m map[string]interface{}) map[string]bool {
+func (v *Viper) mergeFlatMap(shadow map[string]bool, m map[string]any) map[string]bool {
 	// scan keys
 outer:
 	for k := range m {
@@ -2089,13 +2136,17 @@ outer:
 	return shadow
 }

-// AllSettings merges all settings and returns them as a map[string]interface{}.
-func AllSettings() map[string]interface{} { return v.AllSettings() }
+// AllSettings merges all settings and returns them as a map[string]any.
+func AllSettings() map[string]any { return v.AllSettings() }

-func (v *Viper) AllSettings() map[string]interface{} {
-	m := map[string]interface{}{}
+func (v *Viper) AllSettings() map[string]any {
+	return v.getSettings(v.AllKeys())
+}
+
+func (v *Viper) getSettings(keys []string) map[string]any {
+	m := map[string]any{}
 	// start from the list of keys, and construct the map one value at a time
-	for _, k := range v.AllKeys() {
+	for _, k := range keys {
 		value := v.Get(k)
 		if value == nil {
 			// should not happen, since AllKeys() returns only keys holding a value,
@@ -1,32 +0,0 @@
-//go:build go1.16 && finder
-// +build go1.16,finder
-
-package viper
-
-import (
-	"fmt"
-
-	"github.com/spf13/afero"
-)
-
-// Search all configPaths for any config file.
-// Returns the first path that exists (and is a config file).
-func (v *Viper) findConfigFile() (string, error) {
-	finder := finder{
-		paths:            v.configPaths,
-		fileNames:        []string{v.configName},
-		extensions:       SupportedExts,
-		withoutExtension: v.configType != "",
-	}
-
-	file, err := finder.Find(afero.NewIOFS(v.fs))
-	if err != nil {
-		return "", err
-	}
-
-	if file == "" {
-		return "", ConfigFileNotFoundError{v.configName, fmt.Sprintf("%s", v.configPaths)}
-	}
-
-	return file, nil
-}
@@ -1,12 +0,0 @@
-//go:build darwin || dragonfly || freebsd || openbsd || linux || netbsd || solaris || windows
-// +build darwin dragonfly freebsd openbsd linux netbsd solaris windows
-
-package viper
-
-import "github.com/fsnotify/fsnotify"
-
-type watcher = fsnotify.Watcher
-
-func newWatcher() (*watcher, error) {
-	return fsnotify.NewWatcher()
-}
@@ -1,32 +0,0 @@
-//go:build appengine || (!darwin && !dragonfly && !freebsd && !openbsd && !linux && !netbsd && !solaris && !windows)
-// +build appengine !darwin,!dragonfly,!freebsd,!openbsd,!linux,!netbsd,!solaris,!windows
-
-package viper
-
-import (
-	"fmt"
-	"runtime"
-
-	"github.com/fsnotify/fsnotify"
-)
-
-func newWatcher() (*watcher, error) {
-	return &watcher{}, fmt.Errorf("fsnotify not supported on %s", runtime.GOOS)
-}
-
-type watcher struct {
-	Events chan fsnotify.Event
-	Errors chan error
-}
-
-func (*watcher) Close() error {
-	return nil
-}
-
-func (*watcher) Add(name string) error {
-	return nil
-}
-
-func (*watcher) Remove(name string) error {
-	return nil
-}