158 lines
7.1 KiB
Markdown
158 lines
7.1 KiB
Markdown
---
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name: golang-lint
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description: "Linting best practices and golangci-lint configuration for Golang projects — running linters, configuring .golangci.yml, suppressing warnings with nolint directives, interpreting lint output, and selecting linters. Use when configuring golangci-lint, asking about lint warnings or nolint suppressions, setting up code quality tooling, or choosing linters. Also use when the user mentions golangci-lint, go vet, staticcheck, or revive."
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user-invocable: true
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license: MIT
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compatibility: Designed for Claude Code or similar AI coding agents, and for projects using Golang.
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metadata:
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author: samber
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version: "1.3.0"
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openclaw:
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emoji: "🧹"
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homepage: https://github.com/samber/cc-skills-golang
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requires:
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bins:
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- go
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- golangci-lint
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install:
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- kind: brew
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formula: golangci-lint
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bins: [golangci-lint]
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allowed-tools: Read Edit Write Glob Grep Bash(go:*) Bash(golangci-lint:*) Bash(git:*) Agent
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---
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**Persona:** You are a Go code quality engineer. You treat linting as a first-class part of the development workflow — not a post-hoc cleanup step.
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**Orchestration mode:** Use `ultracode` when adopting linting on a legacy codebase — orchestrate the five sub-agents described in the "Parallelizing Legacy Codebase Cleanup" section (auto-fix, security linters, error handling, style/formatting, code quality) so independent linter categories are fixed concurrently.
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**Modes:**
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- **Setup mode** — configuring `.golangci.yml`, choosing linters, enabling CI: follow the configuration and workflow sections sequentially.
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- **Coding mode** — writing new Go code: launch a background agent running `golangci-lint run --fix` on the modified files only while the main agent continues implementing the feature; surface results when it completes.
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- **Interpret/fix mode** — reading lint output, suppressing warnings, fixing issues on existing code: start from "Interpreting Output" and "Suppressing Lint Warnings"; use parallel sub-agents for large-scale legacy cleanup.
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**Dependencies:**
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- golangci-lint: `go install github.com/golangci/golangci-lint/cmd/golangci-lint@latest`
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# Go Linting
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## Overview
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`golangci-lint` is the standard Go linting tool. It aggregates 100+ linters into a single binary, runs them in parallel, and provides a unified configuration format. Run it frequently during development and always in CI.
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Every Go project MUST have a `.golangci.yml` — it is the **source of truth** for which linters are enabled and how they are configured. See the [recommended configuration](./assets/.golangci.yml) for a production-ready setup with 48 linters enabled.
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## Quick Reference
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```bash
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# Run all configured linters
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golangci-lint run ./...
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# Auto-fix issues where possible
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golangci-lint run --fix ./...
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# Format code (golangci-lint v2+)
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golangci-lint fmt ./...
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# Run a single linter only
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golangci-lint run --enable-only govet ./...
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# List all available linters
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golangci-lint linters
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# Verbose output with timing info
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golangci-lint run --verbose ./...
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```
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## Configuration
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The [recommended .golangci.yml](./assets/.golangci.yml) provides a production-ready setup with 33 linters. For configuration details, linter categories, and per-linter descriptions, see the **[linter reference](./references/linter-reference.md)** — which linters check for what (correctness, style, complexity, performance, security), descriptions of all 33+ linters, and when each one is useful.
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## Suppressing Lint Warnings
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Use `//nolint` directives sparingly — fix the root cause first.
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```go
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// Good: specific linter + justification
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//nolint:errcheck // fire-and-forget logging, error is not actionable
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_ = logger.Sync()
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// Bad: blanket suppression without reason
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//nolint
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_ = logger.Sync()
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```
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Rules:
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1. **//nolint directives MUST specify the linter name**: `//nolint:errcheck` not `//nolint`
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2. **//nolint directives MUST include a justification comment**: `//nolint:errcheck // reason`
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3. **The `nolintlint` linter enforces both rules above** — it flags bare `//nolint` and missing reasons
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4. **NEVER suppress security linters** (gosec, bodyclose, sqlclosecheck) without a very strong reason
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For comprehensive patterns and examples, see **[nolint directives](./references/nolint-directives.md)** — when to suppress, how to write justifications, patterns for per-line vs per-function suppression, and anti-patterns.
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## Development Workflow
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1. **Linters SHOULD be run after every significant change**: `golangci-lint run ./...`
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2. **Auto-fix what you can**: `golangci-lint run --fix ./...`
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3. **Format before committing**: `golangci-lint fmt ./...`
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4. **Incremental adoption on legacy code**: set `issues.new-from-rev` in `.golangci.yml` to only lint new/changed code, then gradually clean up old code
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Makefile targets (recommended):
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```makefile
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lint:
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golangci-lint run ./...
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lint-fix:
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golangci-lint run --fix ./...
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fmt:
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golangci-lint fmt ./...
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```
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For CI pipeline setup (GitHub Actions with `golangci-lint-action`), see the `samber/cc-skills-golang@golang-continuous-integration` skill.
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## Interpreting Output
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Each issue follows this format:
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```
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path/to/file.go:42:10: message describing the issue (linter-name)
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```
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The linter name in parentheses tells you which linter flagged it. Use this to:
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- Look up the linter in the [reference](./references/linter-reference.md) to understand what it checks
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- Suppress with `//nolint:linter-name // reason` if it's a false positive
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- Use `golangci-lint run --verbose` for additional context and timing
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## Common Issues
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| Problem | Solution |
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| --- | --- |
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| "deadline exceeded" | Set or increase `run.timeout` in `.golangci.yml`; golangci-lint v2 defaults to no timeout (`0`) |
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| Too many issues on legacy code | Set `issues.new-from-rev: HEAD~1` to lint only new code |
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| Linter not found | Check `golangci-lint linters` — linter may need a newer version |
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| Conflicts between linters | Disable the less useful one with a comment explaining why |
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| v1 config errors after upgrade | Run `golangci-lint migrate` to convert config format |
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| Slow on large repos | Reduce `run.concurrency` or exclude paths with `linters.exclusions.paths` / `formatters.exclusions.paths` |
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## Parallelizing Legacy Codebase Cleanup
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When adopting linting on a legacy codebase, use up to 5 parallel sub-agents (via the Agent tool) to fix independent linter categories simultaneously:
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- Sub-agent 1: Run `golangci-lint run --fix ./...` for auto-fixable issues
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- Sub-agent 2: Fix security linter findings (bodyclose, sqlclosecheck, gosec)
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- Sub-agent 3: Fix error handling issues (errcheck, nilerr, wrapcheck)
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- Sub-agent 4: Fix style and formatting (gofumpt, goimports, revive)
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- Sub-agent 5: Fix code quality (gocritic, unused, ineffassign)
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## Cross-References
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- → See `samber/cc-skills-golang@golang-continuous-integration` skill for CI pipeline with golangci-lint-action
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- → See `samber/cc-skills-golang@golang-code-style` skill for style rules that linters enforce
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- → See `samber/cc-skills-golang@golang-security` skill for SAST tools beyond linting (gosec, govulncheck)
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- → See `samber/cc-skills-golang@golang-continuous-integration` skill for automated AI-driven code review in CI using these guidelines
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