Go Code Review

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name: go-code-review description: Auto-review Go code for 100+ common mistakes when analyzing .go files, discussing Go patterns, or reviewing PRs with Go code. Checks error handling, concurrency, interfaces, performance, testing, and stdlib usage. allowed-tools: Read user-invocable: true

Go Code Review Skill

Auto-triggers when reviewing Go code to catch common mistakes from https://100go.co/

Scope

Apply to .go files and Go PRs. Not a substitute for go vet or golangci-lint — use both alongside this review.

Review Process

1. Read Go file(s) mentioned
2. Read knowledge-base.md in full before step 4 — contains all 100+ mistake references
3. Read real-world-patterns.md in full before step 4 — contains OSS project patterns
4. Check each file against both references; identify every applicable mistake
5. Report each mistake with:
   • Severity (Critical/Major/Minor)
   • Location (file:line)
   • Mistake # from knowledge base
   • Suggested fix
   • Code example if applicable
6. Re-read each flagged location to confirm accuracy — remove false positives, escalate any missed Critical mistakes

Severity Tiers

Critical (fix before merge):

• Error handling (#48-54) — silent failures are undebuggable after the fact; callers cannot recover
• Concurrency (#58, 69, 70, 74) — races surface only under load, typically in production
• Resource leaks (#26, 28, 76, 79) — accumulate until OOM or connection pool exhaustion

Major (should fix):

• Interface design (#5-7) — wrong-side interfaces lock in dependencies that are hard to untangle later
• Goroutine lifecycle (#62, 63) — leaked goroutines accumulate until process memory is exhausted
• Testing (#83, 86) — flaky tests mask real bugs and slow CI feedback loop

Minor (consider):

• Code organization (#1, 2, 15) — readability impact only, no correctness risk
• Performance (#21, 27, 39) — matters at scale; verify with profiling before flagging

Edge Cases

• No mistakes found: State explicitly — do not invent issues to appear thorough
• Ambiguous severity: Flag as Critical and explain the context-dependency in the report
• Non-.go files: Skip silently; do not apply Go-specific checks to other file types

func fetchUser(id int) (*User, error) {
    row := db.QueryRow("SELECT * FROM users WHERE id=?", id)
    var u User
    if err := row.Scan(&u.Name, &u.Email); err != nil {
        return nil, err
    }
    return &u, nil
}

Output:

Mistake: #49 — Ignoring When to Wrap an Error Severity: Major Location: handler.go:5 Fix: return nil, fmt.Errorf("fetchUser id=%d: %w", id, err) Why: Without %w, callers cannot trace origin; errors.Is/errors.As chains break