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fix(ty_utils): try normalize earsing regions#111259

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bvanjoi:fix-110630
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fix(ty_utils): try normalize earsing regions#111259
bvanjoi wants to merge 1 commit intorust-lang:masterfrom
bvanjoi:fix-110630

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@bvanjoi bvanjoi commented May 5, 2023 •
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close #110630

#105561 introduces normalize_erasing_regions for the substs in resolve_instance, this is quite general and can apply to any type. However, it poses a problem for issue #110630, where I as Concat will trigger a bug because Concat is not implemented for I.

In order to solve #110630, this PR:

  • had raised normalize function call, which requires that we now use the normalized substs when necessary.
  • attempting to normalize the substs before resolve during const_eval_resolve_for_typeck, if it failed, we will return TooGeneric error

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rustbot commented May 5, 2023

r? @cjgillot

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@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels May 5, 2023
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compiler-errors suggested changes May 5, 2023
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This PR description really needs more information about:

  1. Why it happens
  2. Why this fix is correct

@compiler-errors compiler-errors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels May 5, 2023
@compiler-errors compiler-errors self-assigned this May 5, 2023
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bvanjoi commented May 6, 2023

This PR description really needs more information about:

  1. Why it happens
  2. Why this fix is correct

Thanks for your advice, I will try to add more descriptions

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rustbot commented May 6, 2023

Some changes occurred to the CTFE / Miri engine

cc @rust-lang/miri

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bvanjoi commented May 6, 2023
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compiler/rustc_lint/src/internal.rs
impl LateLintPass<'_> for QueryStability {
fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
let Some((span, def_id, substs)) = typeck_results_of_method_fn(cx, expr) else { return };
let substs = cx.tcx.normalize_erasing_regions(cx.param_env, substs);
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for #105561

compiler/rustc_lint/src/internal.rs
impl LateLintPass<'_> for Diagnostics {
fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
let Some((span, def_id, substs)) = typeck_results_of_method_fn(cx, expr) else { return };
let substs = cx.tcx.normalize_erasing_regions(cx.param_env, substs);
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for #105561

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bvanjoi commented May 6, 2023 •
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@rustbot ready

@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels May 6, 2023
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BoxyUwU commented May 11, 2023

generic_const_exprs currently evaluates constants without their where clauses holding, resulting in us attempting to do things like this on not-wf code. I do not think this PR is the correct solution to the linked issue, we really ought to be ensuring that ConstKind::Unevaluated is wf before attempting to evaluate it. Replacing infallible stuff with fallible stuff just to mask ICEs caused by this bug doesn't seem desirable to me.

Unfortunately it is not possible right now to "just" check ConstKind::Unevaluated is wf before evaluating it so I do not think it is possible to fix the linked issue in a satisfactory way. The bug here is tracked in rust-lang/project-const-generics#37 and there are a fair amount of issues open with the F-generic_const_exprs label caused by it.

@oli-obk oli-obk added S-blocked Status: Blocked on something else such as an RFC or other implementation work. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels May 12, 2023
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bors commented Jul 14, 2023

☔ The latest upstream changes (presumably #113591) made this pull request unmergeable. Please resolve the merge conflicts.

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Dylan-DPC commented Aug 10, 2023

@bvanjoi any updates on this? thanks

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bvanjoi commented Aug 10, 2023

Closed this as it is invalid.

@bvanjoi bvanjoi closed this Aug 10, 2023
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ICE: failed to normalize, generic_const_exprs

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