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Auto merge of #100571 - cjgillot:mir-cost-visit, r=compiler-errors

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Check projection types before inlining MIR

Fixes https://github.com/rust-lang/rust/issues/100550

I'm very unhappy with this solution, having to duplicate MIR validation code, but at least it removes the ICE.

r? `@compiler-errors`
This commit is contained in:
bors 2022-08-25 08:16:43 +00:00
commit 4d45b0745a
3 changed files with 266 additions and 108 deletions
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30
compiler/rustc_const_eval/src/transform/validate.rs
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@ -89,22 +89,20 @@ pub fn equal_up_to_regions<'tcx>(
// Normalize lifetimes away on both sides, then compare.
let normalize = |ty: Ty<'tcx>| {
tcx.normalize_erasing_regions(
param_env,
ty.fold_with(&mut BottomUpFolder {
tcx,
// FIXME: We erase all late-bound lifetimes, but this is not fully correct.
// If you have a type like `<for<'a> fn(&'a u32) as SomeTrait>::Assoc`,
// this is not necessarily equivalent to `<fn(&'static u32) as SomeTrait>::Assoc`,
// since one may have an `impl SomeTrait for fn(&32)` and
// `impl SomeTrait for fn(&'static u32)` at the same time which
// specify distinct values for Assoc. (See also #56105)
lt_op: |_| tcx.lifetimes.re_erased,
// Leave consts and types unchanged.
ct_op: |ct| ct,
ty_op: |ty| ty,
}),
)
let ty = ty.fold_with(&mut BottomUpFolder {
tcx,
// FIXME: We erase all late-bound lifetimes, but this is not fully correct.
// If you have a type like `<for<'a> fn(&'a u32) as SomeTrait>::Assoc`,
// this is not necessarily equivalent to `<fn(&'static u32) as SomeTrait>::Assoc`,
// since one may have an `impl SomeTrait for fn(&32)` and
// `impl SomeTrait for fn(&'static u32)` at the same time which
// specify distinct values for Assoc. (See also #56105)
lt_op: |_| tcx.lifetimes.re_erased,
// Leave consts and types unchanged.
ct_op: |ct| ct,
ty_op: |ty| ty,
});
tcx.try_normalize_erasing_regions(param_env, ty).unwrap_or(ty)
};
tcx.infer_ctxt().enter(|infcx| infcx.can_eq(param_env, normalize(src), normalize(dest)).is_ok())
}