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gofmt & goimports

# Canonical, non-configurable formatting as a language feature, goimports for import blocks, and gofumpt as the stricter superset.

Conceptsaved 2026-08-09 #go#tooling#formatting

Overview

gofmt prints Go source in the one canonical style — no configuration file, no options to argue over. "Gofmt's style is no one's favourite, yet gofmt is everyone's favourite": by removing formatting from the review surface entirely, diffs show only meaning. It is best understood as a language feature, not a lint.

Key points

  • Zero configuration: no line-length knob, no brace-style debate; tabs, and that's the end of the conversation. Every Go codebase on earth is formatted identically.
  • gofmt -w . rewrites in place; gofmt -l lists non-conforming files (the CI check). go fmt ./... is the module-aware wrapper.
  • gofmt -r 'a[b:len(a)] -> a[b:]': pattern-based rewrites — a lightweight refactoring tool using single-lowercase-letter wildcards over expressions.
  • goimports = gofmt + imports: adds missing and removes unused import statements, grouping stdlib before third-party; ships in golang.org/x/tools. In practice you run goimports and get gofmt for free.
  • Editor-on-save is the convention: nobody formats manually — gopls applies gofmt/goimports on save in every mainstream editor setup, so the topic simply disappears from daily work.
  • gofumpt: a stricter superset (extra rules like no empty lines at block starts, shorter octal literals); gofumpt-formatted code is always gofmt-compliant, so adopting it is safe. Supported natively as a gopls formatting backend.
  • Format-on-CI, not format-debates-on-PR: a gofmt -l gate plus on-save formatting makes style review comments extinct — the cultural payoff Java teams buy with checkstyle/spotless configuration.

Examples

gofmt -l ./...                       # CI: fail if output non-empty
gofmt -r 'interface{} -> any' -w .   # mechanical modernization
goimports -w -local github.com/acme ./...   # group company imports last

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