rust-lang / rust-lang/rust

Trivial bounds check doesn't consider non-global predicates *after* normalization

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#140,309 0 comments 0 reactions 1 assignee View on GitHub

@lcnr is already working on this.

Since Apr 25, 2025.

C-bug T-types
Dominant language
Rust
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Description

trait Hello {}
impl<const N: usize> Hello for [(); N] {}

trait Foo {
    type Assoc;
}

fn foo<const N: usize>()
where
    <u32 as Foo>::Assoc: Hello,
    u32: Foo<Assoc = [(); N]>,
{
}

I expected to see this pass.

Instead, this ICEd.

<u32 as Foo>::Assoc: Hello is considered global, but it is not global.

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