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https://github.com/rust-lang/rust
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29 lines
843 B
Rust
29 lines
843 B
Rust
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/// Discovered in https://github.com/rust-lang/rust/issues/112602.
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/// This caused a cycle error, which made no sense.
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/// Removing the `const` part of the `many` function would make the
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/// test pass again.
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/// The issue was that we were running const qualif checks on
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/// `const fn`s, but never using them. During const qualif checks we tend
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/// to end up revealing opaque types (the RPIT in `many`'s return type),
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/// which can quickly lead to cycles.
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pub struct Parser<H>(H);
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impl<H, T> Parser<H>
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where
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H: for<'a> Fn(&'a str) -> T,
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{
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pub const fn new(handler: H) -> Parser<H> {
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Parser(handler)
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}
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pub const fn many<'s>(&'s self) -> Parser<impl for<'a> Fn(&'a str) -> Vec<T> + 's> {
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//~^ ERROR: cycle detected
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Parser::new(|_| unimplemented!())
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}
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}
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fn main() {
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println!("Hello, world!");
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}
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