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Auto merge of #127172 - compiler-errors:full-can_eq-everywhere, r=lcnr

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Make `can_eq` process obligations (almost) everywhere

Move `can_eq` to an extension trait on `InferCtxt` in `rustc_trait_selection`, and change it so that it processes obligations. This should strengthen it to be more accurate in some cases, but is most important for the new trait solver which delays relating aliases to `AliasRelate` goals. Without this, we always basically just return true when passing aliases to `can_eq`, which can lead to weird errors, for example #127149.

I'm not actually certain if we should *have* `can_eq` be called on the good path. In cases where we need `can_eq`, we probably should just be using a regular probe.

Fixes #127149

r? lcnr
This commit is contained in:
bors
2024-07-07 23:03:48 +00:00
parent 20ae37c18d 465e7d546e
commit 89aefb9c53
30 changed files with 133 additions and 154 deletions
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11
compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs
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@@ -1,5 +1,10 @@
use super::{ObligationCauseCode, PredicateObligation};
use crate::errors::{
EmptyOnClauseInOnUnimplemented, InvalidOnClauseInOnUnimplemented, NoValueInOnUnimplemented,
};
use crate::infer::error_reporting::TypeErrCtxt;
use crate::infer::InferCtxtExt;
use crate::traits::error_reporting::type_err_ctxt_ext::InferCtxtPrivExt;
use rustc_ast::AttrArgs;
use rustc_ast::AttrArgsEq;
use rustc_ast::AttrKind;
@@ -21,12 +26,6 @@ use rustc_span::Span;
use std::iter;
use std::path::PathBuf;
use crate::errors::{
EmptyOnClauseInOnUnimplemented, InvalidOnClauseInOnUnimplemented, NoValueInOnUnimplemented,
};
use crate::traits::error_reporting::type_err_ctxt_ext::InferCtxtPrivExt;
/// The symbols which are always allowed in a format string
static ALLOWED_FORMAT_SYMBOLS: &[Symbol] = &[
kw::SelfUpper,

2
compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
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@@ -1073,7 +1073,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
// mismatched, then we have a totally different error to report.
if self.enter_forall(found_args, |found_args| {
self.enter_forall(expected_args, |expected_args| {
!self.can_sub(obligation.param_env, expected_args, found_args)
!self.can_eq(obligation.param_env, expected_args, found_args)
})
}) {
return None;

2
compiler/rustc_trait_selection/src/traits/select/mod.rs
View File

@@ -18,7 +18,7 @@ use super::{
TraitQueryMode,
};
use crate::infer::{InferCtxt, InferOk, TypeFreshener};
use crate::infer::{InferCtxt, InferCtxtExt, InferOk, TypeFreshener};
use crate::solve::InferCtxtSelectExt as _;
use crate::traits::error_reporting::TypeErrCtxtExt;
use crate::traits::normalize::normalize_with_depth;