ac9a1cb415
This PR introduces stricter inference for the `@[defeq]` attribute and a companion `@[backward_defeq]` attribute that preserves the pre-PR behavior as an opt-in. ### What changed * `@[defeq]` is now inferred only when the equation holds at `.instances` transparency (the transparency `dsimp` operates at). * `@[backward_defeq]` is the old set: every theorem whose `rfl` proof the legacy inference would have accepted is tagged `@[backward_defeq]`, so `defeq ⊆ backward_defeq` holds by construction. * The option `backward.defeqAttrib.useBackward` (default `false`) makes `dsimp` also use `@[backward_defeq]` theorems, restoring the pre-PR behavior for a specific proof or file. * The option is eqn-affecting: its value at the point of a function's definition is recorded so that the equation lemmas later generated for that function use the same value, regardless of the ambient option at the use site. ### Mathlib adaption A companion adaption branch (`lean-pr-testing-backward-defeq-attrib` on mathlib4) builds cleanly against this PR and passes `lake test` without warnings. Most adaption changes are scoped `set_option backward.defeqAttrib.useBackward true in` additions on the failing declarations; a small number of files needed proof-level edits where the stored form of a `dsimp%`/`@[reassoc]`/`@[elementwise]` /`@[simps]`/`@[to_app]`-generated lemma had drifted under the stricter regime. --------- Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
56 lines
1.1 KiB
Text
56 lines
1.1 KiB
Text
/-! Tests that options affecting equational theorems work as expected. -/
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set_option linter.deprecated.options false
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namespace Test1
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def nonrecfun : Bool → Nat
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| false => 0
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| true => 0
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/--
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info: equations:
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@[backward_defeq] theorem Test1.nonrecfun.eq_1 : nonrecfun false = 0
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@[backward_defeq] theorem Test1.nonrecfun.eq_2 : nonrecfun true = 0
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-/
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#guard_msgs in
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#print equations nonrecfun
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end Test1
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namespace Test2
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set_option backward.eqns.nonrecursive false in
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def nonrecfun : Bool → Nat
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| false => 0
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| true => 0
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/--
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info: equations:
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@[backward_defeq] theorem Test2.nonrecfun.eq_1 : ∀ (x : Bool),
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nonrecfun x =
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match x with
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| false => 0
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| true => 0
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-/
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#guard_msgs in
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#print equations nonrecfun
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end Test2
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namespace Test3
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def nonrecfun : Bool → Nat
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| false => 0
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| true => 0
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-- should have no effect
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set_option backward.eqns.nonrecursive false
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/--
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info: equations:
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@[backward_defeq] theorem Test3.nonrecfun.eq_1 : nonrecfun false = 0
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@[backward_defeq] theorem Test3.nonrecfun.eq_2 : nonrecfun true = 0
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-/
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#guard_msgs in
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#print equations nonrecfun
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end Test3
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