fix: Redundant type instantiation wrong when return expression
#5605
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src/mo_frontend/typing.ml
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| let closed_codom = Bi_match.is_closed remaining codom in | ||
| (* Closed [codom] implies closed [body_typ]. [body_typ] is closed when it comes from [typ_opt] *) | ||
| let closed_body_typ = closed_codom || Option.is_some typ_opt in | ||
| let env' = if closed_body_typ then env' else { env' with rets = None } in |
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Hmm, if env'.rets = None, that means the body can't return at all which is weird because functions can always return. There's only a few places where we disallow returns (e.g. object/class constructors) so maybe we should discuss.
Are you ever checking the body of a function with env'.rets = None? If not, probably ok.
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Oh, I think you are at line 2989
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That is a good point. It's better to distinguish between None and Some here for rets
It should be more like type rets = NotAllowed | RetBimatch | Ret typ.
And a custom error when trying to check when RetBimatch saying that cannot infer type of return etc.
Kamirus
changed the title
return expression
We need to perform the redundancy check before |
src/mo_frontend/typing.ml
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| check_exp_strong env t exp1 | ||
| | None -> | ||
| | BimatchRet k -> | ||
| k env exp1 |
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This will actually wind up doing infer_exp rather than check_exp_strong (as on 2084). God knows if that would make a difference.
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Doing infer is expected, but true I can pass the weak = false here
Continuation in a separate PR here #5615
Kamirus
changed the title
return expressionreturn expression
2 participants
Fix the
M0223warning check for redundant type instantiations to avoid false positives.This check is now correctly performed during
not env.prephase like all other warnings.Also: Correctly handles nested expressions, further avoiding false positives.