rust/tests/ui/const-generics/defaults/doesnt_infer.rs

// test that defaulted const params are not used to help type inference

struct Foo<const N: u32 = 2>;

impl<const N: u32> Foo<N> {
    fn foo() -> Self {
        loop {}
    }
}

fn main() {
    let foo = Foo::<1>::foo();
    let foo = Foo::foo();
    //~^ ERROR type annotations needed for `Foo<_>`
}
Inference 2021-10-20 23:36:50 +01:00			`// test that defaulted const params are not used to help type inference`

			`struct Foo<const N: u32 = 2>;`

			`impl<const N: u32> Foo<N> {`
Partially implement `ConstArgHasType` 2024-05-29 17:06:50 +01:00			`fn foo() -> Self {`
			`loop {}`
			`}`
Inference 2021-10-20 23:36:50 +01:00			`}`

			`fn main() {`
			`let foo = Foo::<1>::foo();`
			`let foo = Foo::foo();`
Use `fn` ptr signature instead of `{closure@..}` in infer error When suggesting a type on inference error, do not use `{closure@..}`. Instead, replace with an appropriate `fn` ptr. On the error message, use `short_ty_string` and write long types to disk. ``` error[E0284]: type annotations needed for `Select<{closure@lib.rs:2782:13}, _, Expression<'_>, _>` --> crates/lang/src/parser.rs:41:13 \| 41 \| let lit = select! { \| ^^^ 42 \| Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()), \| ---- type must be known at this point \| = note: the full type name has been written to '/home/gh-estebank/iowo/target/debug/deps/lang-e2d6e25819442273.long-type-4587393693885174369.txt' = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan` help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified \| 41 \| let lit: Select<for<'a, 'b> fn(tokens::Token<'_>, &'a mut MapExtra<'_, 'b, _, _>) -> Option<Expression<'_>>, _, Expression<'_>, _> = select! { \| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ``` instead of ``` error[E0284]: type annotations needed for `Select<{closure@/home/gh-estebank/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, _, Expression<'_>, _>` --> crates/lang/src/parser.rs:41:13 \| 41 \| let lit = select! { \| ^^^ 42 \| Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()), \| ---- type must be known at this point \| = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan` help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified \| 41 \| let lit: Select<{closure@/home/gh-estebank/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, _, Expression<'_>, _> = select! { \| ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ``` Fix #123630. 2024-04-10 00:11:52 +00:00			//~^ ERROR type annotations needed for `Foo<_>`
Inference 2021-10-20 23:36:50 +01:00			`}`