92db7b2b5a
When a const param doesn't have a `: Type`, recover the parser state and provide a structured suggestion. This not only provides guidance on what was missing, but it also makes subsuequent errors to be emitted that would otherwise be silenced. ``` error: expected `:`, found `>` --> $DIR/incorrect-const-param.rs:26:16 | LL | impl<T, const N> From<[T; N]> for VecWrapper<T> | ^ expected `:` | help: you might have meant to write the type of the const parameter here | LL | impl<T, const N: /* Type */> From<[T; N]> for VecWrapper<T> | ++++++++++++ ```
45 lines
1,020 B
Rust
45 lines
1,020 B
Rust
// #84327
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struct VecWrapper<T>(Vec<T>);
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// Correct
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impl<T, const N: usize> From<[T; N]> for VecWrapper<T>
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where
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T: Clone,
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{
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fn from(slice: [T; N]) -> Self {
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VecWrapper(slice.to_vec())
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}
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}
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// Forgot const
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impl<T, N: usize> From<[T; N]> for VecWrapper<T> //~ ERROR expected value, found type parameter `N`
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where //~^ ERROR expected trait, found builtin type `usize`
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T: Clone,
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{
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fn from(slice: [T; N]) -> Self { //~ ERROR expected value, found type parameter `N`
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VecWrapper(slice.to_vec())
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}
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}
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// Forgot type
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impl<T, const N> From<[T; N]> for VecWrapper<T> //~ ERROR expected `:`, found `>`
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where
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T: Clone,
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{
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fn from(slice: [T; N]) -> Self {
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VecWrapper(slice.to_vec())
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}
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}
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// Forgot const and type
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impl<T, N> From<[T; N]> for VecWrapper<T> //~ ERROR expected value, found type parameter `N`
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where
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T: Clone,
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{
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fn from(slice: [T; N]) -> Self { //~ ERROR expected value, found type parameter `N`
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VecWrapper(slice.to_vec())
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}
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}
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fn main() {}
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