50c19f704b
This PR lets `MVarId.cleanup` chase local declarations (a bit as if they were equalities). Fixes #10710.
77 lines
2.2 KiB
Text
77 lines
2.2 KiB
Text
set_option linter.unusedVariables false
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-- works
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def g' (T : Type) (ls : List T) : (Option (List T)) :=
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match ls with
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| _::tl =>
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let res := Option.attach (g' T tl)
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res.bind fun x => x.val
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| [] => .none
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-- doesn't
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/--
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error: fail to show termination for
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g''
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with errors
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failed to infer structural recursion:
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Not considering parameter T of g'':
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its type is not an inductive
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Not considering parameter ls of g'':
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its type is an inductive datatype
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List T
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and the datatype parameter
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T
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depends on the function parameter
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T
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which is not fixed.
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no parameters suitable for structural recursion
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failed to prove termination, possible solutions:
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- Use `have`-expressions to prove the remaining goals
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- Use `termination_by` to specify a different well-founded relation
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- Use `decreasing_by` to specify your own tactic for discharging this kind of goal
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T✝ : Type
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head✝ : T✝
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tl : List T✝
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x✝ :
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(y : (T : Type) ×' List T) →
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(invImage (fun x => PSigma.casesOn x fun T ls => sizeOf ls) sizeOfWFRel).1 y ⟨T✝, head✝ :: tl⟩ → Option (List y.1)
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res : Option { x // x✝ ⟨T✝, tl⟩ ⋯ = some x } := (x✝ ⟨T✝, tl⟩ ⋯).attach
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T : Type
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ls : List T
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⊢ sizeOf ls < 1 + sizeOf tl
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-/
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#guard_msgs in
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def g'' (T : Type) (ls : List T) : (Option (List T)) :=
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match ls with
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| _::tl =>
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let res := Option.attach (g'' T tl)
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res.bind fun ⟨x,h⟩ => x
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| [] => .none
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/--
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error: failed to prove termination, possible solutions:
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- Use `have`-expressions to prove the remaining goals
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- Use `termination_by` to specify a different well-founded relation
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- Use `decreasing_by` to specify your own tactic for discharging this kind of goal
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T✝ : Type
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head✝ : T✝
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tl : List T✝
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x✝ :
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(y : (T : Type) ×' List T) →
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(invImage (fun x => PSigma.casesOn x fun T ls => sizeOf ls) sizeOfWFRel).1 y ⟨T✝, head✝ :: tl⟩ → Option (List y.1)
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res : Option { x // x✝ ⟨T✝, tl⟩ ⋯ = some x } := (x✝ ⟨T✝, tl⟩ ⋯).attach
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T : Type
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ls : List T
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⊢ sizeOf ls < 1 + sizeOf tl
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-/
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#guard_msgs in
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def g''' (T : Type) (ls : List T) : (Option (List T)) :=
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match ls with
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| _::tl =>
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let res := Option.attach (g''' T tl)
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res.bind fun ⟨x,h⟩ => x
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| [] => .none
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termination_by sizeOf ls
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