cbda692e7e
This PR fixes #12768, where the new `do` elaborator produced a "declaration has free variables" kernel error when the bind continuation's result type was definitionally but not syntactically independent of the bound variable. The fix moves creation of the result type metavariable before `withLocalDecl`, so the unifier must reduce away the dependency. For example, given `def Quoted (x : Nat) := Nat`, the expression `do let val ← pure 3; withStuff val do return 3` would fail because `β` was assigned `Quoted val` rather than `Nat`.
13 lines
284 B
Text
13 lines
284 B
Text
module
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set_option backward.do.legacy false
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set_option linter.unusedVariables.funArgs false in
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def Quoted (x : Nat) := Nat
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def withStuff (x : Nat) (f : IO (Quoted x)) : IO (Quoted x) := f
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def myFunc : IO Nat := do
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let val : Nat ← pure 3
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withStuff val do
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return (3 : Nat)
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