linters: add stringlint custom linter #195

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Merged

yanyi-wego merged 5 commits into main from custom-linters

Jan 22, 2026

linters/stringlint/Makefile

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+    .PHONY: test lint build
+    test:
+    	go test -v ./...
+    lint:
+    	revive -formatter friendly ./...
+    	go vet ./...
+    build:
+    	go build ./...

linters/stringlint/README.md

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+    # stringlint
+    A Go analyzer that detects direct string comparison patterns and recommends using `github.com/wego/pkg/strings` utility functions.
+    ## Installation
+    ### Automatic way (recommended)
+    This follows golangci-lint's "Automatic Way" module plugin flow.
+    Requirements: Go and git.
+. Create `.custom-gcl.yml` in your project:
+    ```yaml
+    version: v2.8.0
+    plugins:
+      - module: github.com/wego/pkg/linters/stringlint
+        version: v0.1.0
+    ```
+. Build custom golangci-lint:
+    ```bash
+    golangci-lint custom
+    ```
+. Configure the plugin in `.golangci.yml`:
+    ```yaml
+    version: "2"
+    linters:
+      enable:
+        - stringlint
+      settings:
+        custom:
+          stringlint:
+            type: "module"
+            description: "Enforces wego/pkg/strings usage"
+    ```
+. Run the resulting custom binary:
+    ```bash
+    ./custom-gcl run ./...
+    ```
+    ### As a standalone tool
+    ```bash
+    go install github.com/wego/pkg/linters/stringlint/cmd/stringlint@latest
+    stringlint ./...
+    ```
+    ## What it detects
+    | Pattern | Suggestion |
+    |---------|------------|
+    | `s == ""` | `wegostrings.IsEmpty(s)` |
+    | `s != ""` | `wegostrings.IsNotEmpty(s)` |
+    | `len(s) == 0` | `wegostrings.IsEmpty(s)` |
+    | `len(s) != 0` | `wegostrings.IsNotEmpty(s)` |
+    | `len(s) > 0` | `wegostrings.IsNotEmpty(s)` |
+    | `len(s) >= 1` | `wegostrings.IsNotEmpty(s)` |
+    | `len(s) < 1` | `wegostrings.IsEmpty(s)` |
+    | `len(s) <= 0` | `wegostrings.IsEmpty(s)` |
+    | `*ptr == ""` | `wegostrings.IsEmptyP(ptr)` |
+    | `*ptr != ""` | `wegostrings.IsNotEmptyP(ptr)` |
+    Reversed comparisons with the literal on the left are also detected, for example:
+    `0 == len(s)`, `0 != len(s)`, `0 < len(s)`, `0 >= len(s)`, `1 <= len(s)`.
+    ## Import Convention
+    The linter uses the alias `wegostrings` to avoid conflict with the stdlib `strings` package:
+    ```go
+    import wegostrings "github.com/wego/pkg/strings"
+    // The linter suggests:
+    if wegostrings.IsEmpty(s) { ... }
+    ```
+    ## Auto-fix
+    The linter provides suggested fixes that can be applied automatically:
+    ```bash
+    # With golangci-lint
+    ./custom-gcl run --fix ./...
+    # With standalone tool
+    stringlint -fix ./...
+    ```
+    **Note**: Auto-fix replaces the comparison but does not add the import statement. You will need to:
+. Run `goimports` to add missing imports
+. Ensure the import uses the `wegostrings` alias
+    ## Development
+    ### Local tests
+    The testdata directory is a standalone module. Run tests from the module root:
+    ```bash
+    go test -v ./...
+    ```
+    ### Using a commit before tagging
+    If you need to consume an untagged commit from another repo, use a Go pseudo-version
+    instead of a raw SHA.
+    ```bash
+    go list -m -json github.com/wego/pkg/linters/stringlint@<commit>
+    ```
+    Then use the returned `Version` value in `.custom-gcl.yml`:
+    ```yaml
+    version: v2.8.0
+    plugins:
+      - module: github.com/wego/pkg/linters/stringlint
+        version: v0.0.0-20260120hhmmss-abcdef123456
+    ```

linters/stringlint/analyzer.go

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+    // Package stringlint provides a Go analyzer that detects direct string
+    // comparison patterns and recommends using github.com/wego/pkg/strings
+    // utility functions instead.
+    package stringlint
+    import (
+    	"go/ast"
+    	"go/token"
+    	"golang.org/x/tools/go/analysis"
+    	"golang.org/x/tools/go/analysis/passes/inspect"
+    	"golang.org/x/tools/go/ast/inspector"
+    )
+    // Analyzer is the stringlint analyzer that checks for direct string comparisons.
+    var Analyzer = &analysis.Analyzer{
+    	Name:     "stringlint",
+    	Doc:      "recommends using github.com/wego/pkg/strings functions over direct string comparisons",
+    	URL:      "https://github.com/wego/pkg/linters/stringlint",
+    	Run:      run,
+    	Requires: []*analysis.Analyzer{inspect.Analyzer},
+    }
+    func run(pass *analysis.Pass) (any, error) {
+    	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+    	nodeFilter := []ast.Node{
+    		(*ast.BinaryExpr)(nil),
+    	}
+    	inspect.Preorder(nodeFilter, func(n ast.Node) {
+    		binExpr := n.(*ast.BinaryExpr)
+    		// Only check comparison operators.
+    		switch binExpr.Op {
+    		case token.EQL, token.NEQ, token.GTR, token.GEQ, token.LSS, token.LEQ:
+    			// continue
+    		default:
+    			return
+    		}
+    		// Check for empty string comparison: s == "" or s != "".
+    		if result := checkEmptyStringComparison(pass, binExpr); result != nil {
+    			reportDiagnostic(pass, binExpr, result)
+    			return
+    		}
+    		// Check for len comparison: len(s) == 0 or len(s) > 0.
+    		if result := checkLenComparison(pass, binExpr); result != nil {
+    			reportDiagnostic(pass, binExpr, result)
+    			return
+    		}
+    	})
+    	return nil, nil
+    }

linters/stringlint/analyzer_test.go

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+    package stringlint_test
+    import (
+    	"testing"
+    	"golang.org/x/tools/go/analysis/analysistest"
+    	"github.com/wego/pkg/linters/stringlint"
+    )
+    func TestAnalyzer(t *testing.T) {
+    	testdata := analysistest.TestData()
+    	analysistest.Run(t, testdata, stringlint.Analyzer, "./example")
+    }
+    func TestAnalyzerWithFixes(t *testing.T) {
+    	testdata := analysistest.TestData()
+    	analysistest.RunWithSuggestedFixes(t, testdata, stringlint.Analyzer, "./example")
+    }

linters/stringlint/cmd/stringlint/main.go

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+    // Command stringlint runs the stringlint analyzer.
+    package main
+    import (
+    	"golang.org/x/tools/go/analysis/singlechecker"
+    	"github.com/wego/pkg/linters/stringlint"
+    )
+    func main() {
+    	singlechecker.Main(stringlint.Analyzer)
+    }

linters/stringlint/go.mod

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+    module github.com/wego/pkg/linters/stringlint
+    go 1.24
+    require (
+    	github.com/golangci/plugin-module-register v0.1.2
+    	golang.org/x/tools v0.32.0
+    )
+    require (
+    	golang.org/x/mod v0.24.0 // indirect
+    	golang.org/x/sync v0.13.0 // indirect
+    )

linters/stringlint/go.sum

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+    github.com/golangci/plugin-module-register v0.1.2 h1:e5WM6PO6NIAEcij3B053CohVp3HIYbzSuP53UAYgOpg=
+    github.com/golangci/plugin-module-register v0.1.2/go.mod h1:1+QGTsKBvAIvPvoY/os+G5eoqxWn70HYDm2uvUyGuVw=
+    github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+    github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+    golang.org/x/mod v0.24.0 h1:ZfthKaKaT4NrhGVZHO1/WDTwGES4De8KtWO0SIbNJMU=
+    golang.org/x/mod v0.24.0/go.mod h1:IXM97Txy2VM4PJ3gI61r1YEk/gAj6zAHN3AdZt6S9Ww=
+    golang.org/x/sync v0.13.0 h1:AauUjRAJ9OSnvULf/ARrrVywoJDy0YS2AwQ98I37610=
+    golang.org/x/sync v0.13.0/go.mod h1:1dzgHSNfp02xaA81J2MS99Qcpr2w7fw1gpm99rleRqA=
+    golang.org/x/tools v0.32.0 h1:Q7N1vhpkQv7ybVzLFtTjvQya2ewbwNDZzUgfXGqtMWU=
+    golang.org/x/tools v0.32.0/go.mod h1:ZxrU41P/wAbZD8EDa6dDCa6XfpkhJ7HFMjHJXfBDu8s=

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