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Rollup merge of #136429 - fmease:gci-fix-def-site-checks, r=BoxyUwU

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GCI: At their def site, actually wfcheck the where-clause & always eval free lifetime-generic constants

* 1st commit: Partially addresses [#136204](https://github.com/rust-lang/rust/issues/136204) by turning const eval errors from post to pre-mono for free lifetime-generic constants.
  * As the linked issue/comment states, on master there's a difference between `const _: () = panic!();` (pre-mono error) and `const _<'a>: () = panic!();` (post-mono error) which feels wrong.
  * With this PR, both become pre-mono ones!
* 2nd commit: Oof, yeah, I missed that in the initial impl!

This doesn't fully address #136204 because I still haven't figured out how & where to properly & best suppress const eval of free constants whose predicates don't hold at the def site. The motivating example is `const _UNUSED: () = () where for<'_delay> String: Copy;` which can also be found over at the tracking issue #113521.

r? compiler-errors or reassign
This commit is contained in:
Jacob Pratt
2025-05-29 04:49:39 +02:00
committed by GitHub
parent ebe9b00602 9f12748086
commit d3c605a051
8 changed files with 64 additions and 38 deletions
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41
compiler/rustc_hir_analysis/src/check/wfcheck.rs
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@@ -298,11 +298,9 @@ fn check_item<'tcx>(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) -> Result<()
check_item_fn(tcx, def_id, ident, item.span, sig.decl)
}
hir::ItemKind::Static(_, ty, ..) => {
check_item_type(tcx, def_id, ty.span, UnsizedHandling::Forbid)
}
hir::ItemKind::Const(_, ty, ..) => {
check_item_type(tcx, def_id, ty.span, UnsizedHandling::Forbid)
check_static_item(tcx, def_id, ty.span, UnsizedHandling::Forbid)
}
hir::ItemKind::Const(_, ty, ..) => check_const_item(tcx, def_id, ty.span, item.span),
hir::ItemKind::Struct(_, _, hir_generics) => {
let res = check_type_defn(tcx, item, false);
check_variances_for_type_defn(tcx, item, hir_generics);
@@ -366,7 +364,7 @@ fn check_foreign_item<'tcx>(
check_item_fn(tcx, def_id, item.ident, item.span, sig.decl)
}
hir::ForeignItemKind::Static(ty, ..) => {
check_item_type(tcx, def_id, ty.span, UnsizedHandling::AllowIfForeignTail)
check_static_item(tcx, def_id, ty.span, UnsizedHandling::AllowIfForeignTail)
}
hir::ForeignItemKind::Type => Ok(()),
}
@@ -1331,14 +1329,13 @@ enum UnsizedHandling {
AllowIfForeignTail,
}
fn check_item_type(
#[instrument(level = "debug", skip(tcx, ty_span, unsized_handling))]
fn check_static_item(
tcx: TyCtxt<'_>,
item_id: LocalDefId,
ty_span: Span,
unsized_handling: UnsizedHandling,
) -> Result<(), ErrorGuaranteed> {
debug!("check_item_type: {:?}", item_id);
enter_wf_checking_ctxt(tcx, ty_span, item_id, |wfcx| {
let ty = tcx.type_of(item_id).instantiate_identity();
let item_ty = wfcx.deeply_normalize(ty_span, Some(WellFormedLoc::Ty(item_id)), ty);
@@ -1388,6 +1385,34 @@ fn check_item_type(
})
}
fn check_const_item(
tcx: TyCtxt<'_>,
def_id: LocalDefId,
ty_span: Span,
item_span: Span,
) -> Result<(), ErrorGuaranteed> {
enter_wf_checking_ctxt(tcx, ty_span, def_id, |wfcx| {
let ty = tcx.type_of(def_id).instantiate_identity();
let ty = wfcx.deeply_normalize(ty_span, Some(WellFormedLoc::Ty(def_id)), ty);
wfcx.register_wf_obligation(ty_span, Some(WellFormedLoc::Ty(def_id)), ty.into());
wfcx.register_bound(
traits::ObligationCause::new(
ty_span,
wfcx.body_def_id,
ObligationCauseCode::SizedConstOrStatic,
),
wfcx.param_env,
ty,
tcx.require_lang_item(LangItem::Sized, None),
);
check_where_clauses(wfcx, item_span, def_id);
Ok(())
})
}
#[instrument(level = "debug", skip(tcx, hir_self_ty, hir_trait_ref))]
fn check_impl<'tcx>(
tcx: TyCtxt<'tcx>,