Add errstklint: Linter to enforce defer errstk.Wrap(&err)

[tomoemon]

Summary

Add errstklint, a linter tool that ensures all functions returning errors include defer errstk.Wrap(&err) for proper stack trace capture.

Features

Standalone CLI Tool

go install github.com/tomoemon/go-errstk/cmd/errstklint@latest
errstklint ./...
errstklint -exclude="generated/*.go,**/mock_*.go" ./...

golangci-lint Plugin Support

# .custom-gcl.yml
version: v1.62.2
plugins:
  - module: 'github.com/tomoemon/go-errstk/errstklint'
    import: 'github.com/tomoemon/go-errstk/errstklint'
    version: v1.0.0

# .golangci.yml
linters:
  settings:
    errstklint:
      exclude:
        - "generated/*.go"
        - "**/mock_*.go"
        - "**/*_test.go"

File Exclusion Patterns

• Supports glob patterns with ** for directory recursion
• Examples: generated/*.go, **/mock_*.go, **/*_test.go

Implementation

Single Module Structure

go-errstk/
├── go.mod                    # Single module for entire project
├── errstk.go                 # Main library (no linter dependencies)
├── errstklint/               # Analyzer package
│   ├── analyzer.go           # go/analysis implementation
│   ├── plugin.go             # golangci-lint plugin entry point
│   ├── analyzer_test.go      # Tests
│   └── testdata/             # Test fixtures
└── cmd/errstklint/           # CLI tool
    └── main.go               # Standalone executable

Dependency Isolation: Library users (import "github.com/tomoemon/go-errstk") don't get linter dependencies. Only projects importing errstklint package get golang.org/x/tools dependencies.

Usage

Detects missing defer:

// ❌ Reported by linter
func GetUser(id string) (user *User, err error) {
    // Missing: defer errstk.Wrap(&err)
    return db.Query(id)
}

// ✅ Passes linter
func GetUser(id string) (user *User, err error) {
    defer errstk.Wrap(&err)
    return db.Query(id)
}

Testing

• ✅ go/analysis analyzer implementation
• ✅ Test cases with testdata
• ✅ golangci-lint plugin integration
• ✅ File exclusion patterns with glob support
• ✅ Single module structure verified
• ✅ CI/CD workflow updated

Test plan

• Create analyzer package with go/analysis
• Implement AST-based defer detection
• Add file exclusion pattern support
• Create standalone CLI tool
• Implement golangci-lint plugin
• Add comprehensive tests
• Update documentation (README, errstklint/README, cmd/errstklint/README)
• Update CI/CD workflow
• Verify go install works correctly

🤖 Generated with Claude Code