fix(exporter): disable impl expr resolution under type aliases #709
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Could you add the required bounds to the type synonym instead? This is the only correct solution I can imagine. |
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That's something we could do, indeed, but that's not trivial. I'm afraid this will cause bugs in the frontend :/ A quite "brutal" way of doing that would be: each time |
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Yeah :( |
franziskuskiefer
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Jun 12, 2024
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This commits disables trait resolution in the context of a type alias definition. Rust doesn't enforce bounds on generic parameters in type aliases, so it is legal to write: ```rust struct Foo<T: Clone>(T); type Synonym<T> = Foo<T>; ``` Thus, if we compute the impl expression for the bound `T: Clone` that appears on the type expression `Foo<T>`, Rustc's trait selection fails: in the context of `Synonym`, `T` indeed doesn't implement `Clone`, _a priori_. This is raising an issue about backends: translating such type synonym with "missing" bounds will fail. See #708. Fixes #707
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This commit disables trait resolution in the context of a type alias definition.
Rust doesn't enforce bounds on generic parameters in type aliases, so it is legal to write:
Thus, if we compute the impl expression for the bound
T: Clonethat appears on the type expressionFoo<T>, Rustc's trait selection fails: in the context ofSynonym,Tindeed doesn't implementClone, a priori.This is raising an issue about backends: translating such type synonyms with "missing" bounds will fail. See
#708. Thus, this PR also introduces an option so that type synonyms are not extracted by default.
Fixes #707 and fixes #708