lean4-htt/tests/lean/4452.lean
Joachim Breitner 117f73fc84
feat: linter.unusedSimpArgs (#8901)
This PR adds a linter (`linter.unusedSimpArgs`) that complains when a
simp argument (`simp [foo]`) is unused. It should do the right thing if
the `simp` invocation is run multiple times, e.g. inside `all_goals`. It
does not trigger when the `simp` call is inside a macro. The linter
message contains a clickable hint to remove the simp argument.

I chose to display a separate warning for each unused argument. This
means that the user has to click multiple times to remove all of them
(and wait for re-elaboration in between). But this just means multiple
endorphine kicks, and the main benefit over a single warning that would
have to span the whole argument list is that already the squigglies tell
the users about unused arguments.

This closes #4483.

Making Init and Std clean wrt to this linter revealed close to 1000
unused simp args, a pleasant experience for anyone enjoying tidying
things: #8905
2025-06-22 09:10:21 +00:00

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Text

def a := 1
@[deprecated "Don't use `hi`." (since := "1970-01-01")]
theorem hi : a = 1 := rfl
attribute [simp] hi
example (h : 1 = b) : a = b := by
simp
guard_target =ₛ 1 = b
exact h
set_option linter.all true
set_option linter.unusedSimpArgs false
example (h : 1 = b) : a = b := by
simp[
hi
]
guard_target =ₛ 1 = b
exact h
@[deprecated "Don't use `hi'`, either." (since := "1970-01-01")]
theorem hi' : True := .intro
example : True := by
-- the warning is on `simp`
simp [
hi' -- warning should be logged here
]