b9243e19be
This PR makes the equational theorems of non-exposed defs private. If the author of a module chose not to expose the body of their function, then they likely don't want that implementation to leak through equational theorems. Helps with #8419. There is some amount of incidential complexity due to how `private` works in lean, by mangling the name: lots of code paths that need now do the right thing™ about private and non-private names, including the whole reserved name machinery. So this includes a number of refactorings: * The logic for calculating an equational theorem name (or similar) is now done by a single function, `mkEqLikeNameFor`, rather than all over the place. * Since the name of the equational theorem now depends on the current context (in particular whether it’s a proper module, or a non-module file), the forward map from declaration to equational theorem doesn’t quite work anymore. This map is deleted; the list of equational theorems are now always found by looking for declaration of the expected names (`alreadyGenerated). If users define such theorems themselves (and make it past the “do not allow reserved names to be declared”) they get to keep both pieces. * Because this map was deleted, mathlib’s `eqns` command can no longer easily warn if equational lemmas have already been generated too early (adaption branch exists). But in general I think lean could provide a more principled way of supporting custom unfold lemmas, and ideally the whole equational theorem machinery is just using that. * The ReservedNamePredicate is used by `resolveExact`, so we need to make sure that it returns the right name, including privateness. It is not ok to just reserve both the private and non-private name but then later in the ReservedNameAction produce just one of the two. * We create `foo.def_eq` eagerly for well-founded recursion. This is needed because we need feed in the proof of the rewriting done by `wf_preprocess`. But if `foo.def_eq` is private in a module, then a non-module importing it will still expect a non-private `foo.def_eq` to exist. To patch that, we install a `copyPrivateUnfoldTheorem : GetUnfoldEqnFn` that declares a theorem aliasing the private one. Seems to work.
97 lines
2.1 KiB
Text
97 lines
2.1 KiB
Text
module
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prelude
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import Module.Basic
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/-! Theorems should be exported without their bodies -/
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/--
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info: theorem t : f = 1 :=
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<not imported>
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-/
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#guard_msgs in
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#print t
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/-- error: dsimp made no progress -/
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#guard_msgs in
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example : f = 1 := by dsimp only [t]
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example : t = t := by dsimp only [trfl]
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/--
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error: invalid field 'eq_def', the environment does not contain 'Nat.eq_def'
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f
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has type
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Nat
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-/
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#guard_msgs in
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#check f.eq_def
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/--
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error: invalid field 'eq_unfold', the environment does not contain 'Nat.eq_unfold'
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f
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has type
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Nat
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-/
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#guard_msgs in
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#check f.eq_unfold
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/-- error: unknown constant 'f_struct.eq_1' -/
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#guard_msgs in
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#check f_struct.eq_1
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/-- error: unknown constant 'f_struct.eq_def' -/
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#guard_msgs in
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#check f_struct.eq_def
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/-- error: unknown constant 'f_struct.eq_unfold' -/
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#guard_msgs in
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#check f_struct.eq_unfold
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/-- error: unknown constant 'f_wfrec.eq_1' -/
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#guard_msgs in
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#check f_wfrec.eq_1
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/-- error: unknown constant 'f_wfrec.eq_def' -/
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#guard_msgs in
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#check f_wfrec.eq_def
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/-- error: unknown constant 'f_wfrec.eq_unfold' -/
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#guard_msgs in
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#check f_wfrec.eq_unfold
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/-- error: unknown constant 'f_wfrec.induct_unfolding' -/
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#guard_msgs(pass trace, all) in
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#check f_wfrec.induct_unfolding
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/-- info: f_exp_wfrec.eq_1 (x✝ : Nat) : f_exp_wfrec 0 x✝ = x✝ -/
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#guard_msgs in
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#check f_exp_wfrec.eq_1
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/--
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info: f_exp_wfrec.eq_def (x✝ x✝¹ : Nat) :
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f_exp_wfrec x✝ x✝¹ =
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match x✝, x✝¹ with
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| 0, acc => acc
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| n.succ, acc => f_exp_wfrec n (acc + 1)
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-/
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#guard_msgs in
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#check f_exp_wfrec.eq_def
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/--
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info: f_exp_wfrec.eq_unfold :
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f_exp_wfrec = fun x x_1 =>
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match x, x_1 with
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| 0, acc => acc
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| n.succ, acc => f_exp_wfrec n (acc + 1)
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-/
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#guard_msgs in
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#check f_exp_wfrec.eq_unfold
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/--
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info: f_exp_wfrec.induct_unfolding (motive : Nat → Nat → Nat → Prop) (case1 : ∀ (acc : Nat), motive 0 acc acc)
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(case2 : ∀ (n acc : Nat), motive n (acc + 1) (f_exp_wfrec n (acc + 1)) → motive n.succ acc (f_exp_wfrec n (acc + 1)))
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(a✝ a✝¹ : Nat) : motive a✝ a✝¹ (f_exp_wfrec a✝ a✝¹)
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-/
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#guard_msgs(pass trace, all) in
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#check f_exp_wfrec.induct_unfolding
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