v0.12.0

Unused directives get their own rule, unused, with three modes. rules.unused: strict also reports a scope directive that restates the scope a declaration already has under the current config, and -fix deletes it.

Important

This release changes which ignore silences an unused report. Unused reports now carry the unused rule. //declscope:ignore directive no longer silences them: write //declscope:ignore unused. A leftover ignore directive is itself reported, so a run finds each one. See Migrating.

Two rules: unused and directive

Rule	Reports	Config
unused	A //declscope:ignore that silenced nothing, and a //declscope:package or //declscope:private that changes no scope	rules.unused: off | loose | strict, default loose
directive	Malformed, unknown, conflicting and misplaced directives	No key, always on

rules.unused: off | loose | strict

Mode	//declscope:ignore is reported when	//declscope:package or //declscope:private is reported when	-fix
off	Never	Never	None
loose (default)	It silenced no report	Deleting it would change no declaration's scope under any config	None
strict	It silenced no report	Deleting it would change no declaration's scope under the current config	Deletes the directive, unless another report depends on it

package app

type user struct {
	//declscope:private
	name string
}

//declscope:package
func Helper() {}

//declscope:ignore boundary
func greet(u user) string { return u.name }

Line	off	loose	strict
4	Nothing	Nothing	unused //declscope:private on user.name: it already has private scope
8	Nothing	unused //declscope:package on Helper: nothing it reaches takes a scope	unused //declscope:package on Helper: it already has package scope
11	Nothing	unused //declscope:ignore boundary on greet	unused //declscope:ignore boundary on greet

Line 4 is private only because defaults.unexported is private. loose does not rely on the current config, so it keeps the directive. strict reports it.

loose stays the default, so no new report appears without a config edit. To opt in:

rules:
  unused: strict

Warning

Under strict, changing defaults.unexported changes the reports. Every directive that restates the new default is reported. One -fix run deletes them.

declscope survey names the mode among the rules in force, for example unused strict, and "unused": "strict" in the JSON rules object.

Which ignore silences an unused report

The ignore	Silences an unused report for
//declscope:ignore unused on the declaration	The scope directive and the other ignores beside it
Bare //declscope:ignore on the declaration	The scope directive beside it
//declscope:ignore unused, or a bare one, above the package clause	Every directive in the file
//declscope:ignore unused on a block or a type	Nothing inside it

No ignore silences its own unused report. This now holds for a file-level ignore too, which used to silence its own report.

Fixes

• Generic structs. An unkeyed literal such as pair[string]{1, "x"} and a conversion from an instantiation now count as uses of the struct's fields. boundary missed a private field used that way, and surplus: strict could suggest narrowing it.
• False unused reports under loose. A spec's directive is now judged against the block directive it overrides. A spec's //declscope:private under a //declscope:package block was reported as unused, although deleting it widens the spec.
• Accurate block and file-level messages. An unused block or file-level directive names what is true: every spec states its own scope, the named specs already have that scope, or a nearer directive decides.
• Directive on func _. It is reported as no checked declaration carries it, as on var _, instead of misplaced.
• Config errors. An unknown key under filter lists the keys the section takes. A filter pattern that leaves its config's directory is refused as filter "...", not exclude "...".

Migrating

You see	Do this
unused //declscope:ignore directive on X next to another unused report on X	Change it to //declscope:ignore unused
unused file-level //declscope:ignore ...	Remove the ignore. It silenced nothing, including its own report

Full changelog: v0.11.0...v0.12.0