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MGCA: require #[type_const] on free consts too

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This commit is contained in:
khyperia 2026-02-06 15:35:18 +01:00
parent 035b01b794
commit e6f5b97152
14 changed files with 125 additions and 50 deletions
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65
compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
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@ -1422,14 +1422,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
LowerTypeRelativePathMode::Const,
)? {
TypeRelativePath::AssocItem(def_id, args) => {
if !self.tcx().is_type_const(def_id) {
let mut err = self.dcx().struct_span_err(
span,
"use of trait associated const without `#[type_const]`",
);
err.note("the declaration in the trait must be marked with `#[type_const]`");
return Err(err.emit());
}
self.require_type_const_attribute(def_id, span)?;
let ct = Const::new_unevaluated(tcx, ty::UnevaluatedConst::new(def_id, args));
let ct = self.check_param_uses_if_mcg(ct, span, false);
Ok(ct)
@ -1885,30 +1878,18 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
item_def_id: DefId,
trait_segment: Option<&hir::PathSegment<'tcx>>,
item_segment: &hir::PathSegment<'tcx>,
) -> Const<'tcx> {
match self.lower_resolved_assoc_item_path(
) -> Result<Const<'tcx>, ErrorGuaranteed> {
let (item_def_id, item_args) = self.lower_resolved_assoc_item_path(
span,
opt_self_ty,
item_def_id,
trait_segment,
item_segment,
ty::AssocTag::Const,
) {
Ok((item_def_id, item_args)) => {
if !self.tcx().is_type_const(item_def_id) {
let mut err = self.dcx().struct_span_err(
span,
"use of `const` in the type system without `#[type_const]`",
);
err.note("the declaration must be marked with `#[type_const]`");
return Const::new_error(self.tcx(), err.emit());
}
let uv = ty::UnevaluatedConst::new(item_def_id, item_args);
Const::new_unevaluated(self.tcx(), uv)
}
Err(guar) => Const::new_error(self.tcx(), guar),
}
)?;
self.require_type_const_attribute(item_def_id, span)?;
let uv = ty::UnevaluatedConst::new(item_def_id, item_args);
Ok(Const::new_unevaluated(self.tcx(), uv))
}
/// Lower a [resolved][hir::QPath::Resolved] (type-level) associated item path.
@ -2668,6 +2649,10 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
self.lower_const_param(def_id, hir_id)
}
Res::Def(DefKind::Const, did) => {
if let Err(guar) = self.require_type_const_attribute(did, span) {
return Const::new_error(self.tcx(), guar);
}
assert_eq!(opt_self_ty, None);
let [leading_segments @ .., segment] = path.segments else { bug!() };
let _ = self
@ -2718,6 +2703,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
trait_segment,
path.segments.last().unwrap(),
)
.unwrap_or_else(|guar| Const::new_error(tcx, guar))
}
Res::Def(DefKind::Static { .. }, _) => {
span_bug!(span, "use of bare `static` ConstArgKind::Path's not yet supported")
@ -2843,6 +2829,33 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
.map(|l| tcx.at(expr.span).lit_to_const(l))
}
fn require_type_const_attribute(
&self,
def_id: DefId,
span: Span,
) -> Result<(), ErrorGuaranteed> {
let tcx = self.tcx();
if tcx.is_type_const(def_id) {
Ok(())
} else {
let mut err = self
.dcx()
.struct_span_err(span, "use of `const` in the type system without `#[type_const]`");
if def_id.is_local() {
let name = tcx.def_path_str(def_id);
err.span_suggestion(
tcx.def_span(def_id).shrink_to_lo(),
format!("add `#[type_const]` attribute to `{name}`"),
format!("#[type_const]\n"),
Applicability::MaybeIncorrect,
);
} else {
err.note("only consts marked with `#[type_const]` may be used in types");
}
Err(err.emit())
}
}
fn lower_delegation_ty(&self, idx: hir::InferDelegationKind) -> Ty<'tcx> {
let delegation_sig = self.tcx().inherit_sig_for_delegation_item(self.item_def_id());
match idx {