Auto merge of #117589 - compiler-errors:global-vars-bug, r=jackh726

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Make sure that predicates with unmentioned bound vars are still considered global in the old solver

In the old solver, we consider predicates with late-bound vars to not be "global":
9c8a2694fa/compiler/rustc_trait_selection/src/traits/select/mod.rs (L1840-L1844)

The implementation of `has_late_bound_vars` was modified in #115834 so that we'd properly anonymize binders that had late-bound vars but didn't reference them. This fixed an ICE.

However, this also led to a behavioral change in https://github.com/rust-lang/rust/issues/117056#issuecomment-1775014545 for a couple of crates, which now consider `for<'a> GL33: Shader` (note the binder var that is *not* used in the predicate) to not be "global". This forces associated types to not be normalizable due to the old trait solver being dumb.

This PR distinguishes types which *reference* late-bound vars and binders which *have* late-bound vars. The latter is represented with the new type flag `TypeFlags::HAS_BINDER_VARS`, which is used when we only care about knowing whether binders have vars in their bound var list (even if they're not used, like for binder anonymization).

This should fix (after beta backport) the `luminance-gl` and `luminance-webgl` crates in #117056.

r? types
**(priority is kinda high on a review here given beta becomes stable on November 16.)**

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bors 2023-11-05 03:58:09 +00:00

parent c024a3934f 898f18c41b

commit 6a78b12296

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