Improve error message for type mismatch in generator arguments #88911
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…nkov Improve error message for type mismatch in generator arguments Fixes rust-lang#88653. The code example given there is invalid because the `Generator` trait (unlike the `Fn` traits) does not take the generator arguments in tupled-up form (because there can only be one argument, from my understanding). Hence, the type error in the example in rust-lang#88653 is correct, because the given generator takes a `bool` argument, whereas the function's return type talks about a generator with a `(bool,)` argument. The error message is both confusing and wrong, though: It is wrong because it displays the wrong "expected signature", and it is confusing because both the "expected" and "found" notes point at the same span. With my changes, I get the following, more helpful output: ``` error[E0631]: type mismatch in generator arguments --> test.rs:5:22 | 5 | fn foo(bar: bool) -> impl Generator<(bool,)> { | ^^^^^^^^^^^^^^^^^^^^^^^ expected signature of `fn((bool,)) -> _` 6 | |bar| { | ----- found signature of `fn(bool) -> _` ```
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Rollup of 10 pull requests Successful merges: - rust-lang#86382 (Make diagnostics clearer for `?` operators) - rust-lang#87529 (Fix ICE in `improper_ctypes_definitions` lint with all-ZST transparent types) - rust-lang#88339 (Add TcpListener::into_incoming and IntoIncoming) - rust-lang#88735 (Don't lint about missing code examples in derived traits) - rust-lang#88751 (Couple of changes to FileSearch and SearchPath) - rust-lang#88883 (Move some tests to more reasonable directories - 7) - rust-lang#88887 (Const Deref) - rust-lang#88911 (Improve error message for type mismatch in generator arguments) - rust-lang#89014 (PassWrapper: handle separate Module*SanitizerPass) - rust-lang#89033 (Set the library path in sysroot-crates-are-unstable) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
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Fixes #88653. The code example given there is invalid because the
Generatortrait (unlike theFntraits) does not take the generator arguments in tupled-up form (because there can only be one argument, from my understanding). Hence, the type error in the example in #88653 is correct, because the given generator takes aboolargument, whereas the function's return type talks about a generator with a(bool,)argument.The error message is both confusing and wrong, though: It is wrong because it displays the wrong "expected signature", and it is confusing because both the "expected" and "found" notes point at the same span. With my changes, I get the following, more helpful output: