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Enforce tail call type is related to body return type in borrowck #144917

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Merged
bors merged 2 commits into from
Aug 7, 2025
Merged

Enforce tail call type is related to body return type in borrowck #144917

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c7ea022
Enforce tail call type is related to body return type in borrowck
compiler-errors Aug 4, 2025
a573fd9
Don't actually pass BB to check_call_dest
compiler-errors Aug 4, 2025
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Don't actually pass BB to check_call_dest
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@compiler-errors
compiler-errors committed Aug 4, 2025
commit a573fd958eee4b4ec76bdaa3dcacf1ab3c670d45
114 changes: 54 additions & 60 deletions compiler/rustc_borrowck/src/type_check/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -769,9 +769,13 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
}
TerminatorKind::Call { func, args, .. }
| TerminatorKind::TailCall { func, args, .. } => {
let call_source = match term.kind {
TerminatorKind::Call { call_source, .. } => call_source,
TerminatorKind::TailCall { .. } => CallSource::Normal,
let (call_source, destination, is_diverging) = match term.kind {
TerminatorKind::Call { call_source, destination, target, .. } => {
(call_source, destination, target.is_none())
}
TerminatorKind::TailCall { .. } => {
(CallSource::Normal, RETURN_PLACE.into(), false)
}
_ => unreachable!(),
};

Expand Down Expand Up @@ -845,13 +849,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
);
}

let (destination, target) =
if let TerminatorKind::Call { destination, target, .. } = term.kind {
(destination, target)
} else {
(RETURN_PLACE.into(), Some(BasicBlock::ZERO))
};
self.check_call_dest(term, &sig, destination, target, term_location);
self.check_call_dest(term, &sig, destination, is_diverging, term_location);

// The ordinary liveness rules will ensure that all
// regions in the type of the callee are live here. We
Expand Down Expand Up @@ -1878,65 +1876,61 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
term: &Terminator<'tcx>,
sig: &ty::FnSig<'tcx>,
destination: Place<'tcx>,
target: Option<BasicBlock>,
is_diverging: bool,
term_location: Location,
) {
let tcx = self.tcx();
match target {
Some(_) => {
let dest_ty = destination.ty(self.body, tcx).ty;
let dest_ty = self.normalize(dest_ty, term_location);
let category = match destination.as_local() {
Some(RETURN_PLACE) => {
if let DefiningTy::Const(def_id, _) | DefiningTy::InlineConst(def_id, _) =
self.universal_regions.defining_ty
{
if tcx.is_static(def_id) {
ConstraintCategory::UseAsStatic
} else {
ConstraintCategory::UseAsConst
}
if is_diverging {
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@compiler-errors compiler-errors Aug 4, 2025

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I don't really care about the ordering here but the true branch seemed easier to put first

// The signature in this call can reference region variables,
// so erase them before calling a query.
let output_ty = self.tcx().erase_regions(sig.output());
if !output_ty
.is_privately_uninhabited(self.tcx(), self.infcx.typing_env(self.infcx.param_env))
{
span_mirbug!(self, term, "call to converging function {:?} w/o dest", sig);
}
} else {
let dest_ty = destination.ty(self.body, tcx).ty;
let dest_ty = self.normalize(dest_ty, term_location);
let category = match destination.as_local() {
Some(RETURN_PLACE) => {
if let DefiningTy::Const(def_id, _) | DefiningTy::InlineConst(def_id, _) =
self.universal_regions.defining_ty
{
if tcx.is_static(def_id) {
ConstraintCategory::UseAsStatic
} else {
ConstraintCategory::Return(ReturnConstraint::Normal)
ConstraintCategory::UseAsConst
}
} else {
ConstraintCategory::Return(ReturnConstraint::Normal)
}
Some(l) if !self.body.local_decls[l].is_user_variable() => {
ConstraintCategory::Boring
}
// The return type of a call is interesting for diagnostics.
_ => ConstraintCategory::Assignment,
};

let locations = term_location.to_locations();

if let Err(terr) = self.sub_types(sig.output(), dest_ty, locations, category) {
span_mirbug!(
self,
term,
"call dest mismatch ({:?} <- {:?}): {:?}",
dest_ty,
sig.output(),
terr
);
}

// When `unsized_fn_params` is not enabled,
// this check is done at `check_local`.
if self.unsized_feature_enabled() {
let span = term.source_info.span;
self.ensure_place_sized(dest_ty, span);
Some(l) if !self.body.local_decls[l].is_user_variable() => {
ConstraintCategory::Boring
}
// The return type of a call is interesting for diagnostics.
_ => ConstraintCategory::Assignment,
};

let locations = term_location.to_locations();

if let Err(terr) = self.sub_types(sig.output(), dest_ty, locations, category) {
span_mirbug!(
self,
term,
"call dest mismatch ({:?} <- {:?}): {:?}",
dest_ty,
sig.output(),
terr
);
}
None => {
// The signature in this call can reference region variables,
// so erase them before calling a query.
let output_ty = self.tcx().erase_regions(sig.output());
if !output_ty.is_privately_uninhabited(
self.tcx(),
self.infcx.typing_env(self.infcx.param_env),
) {
span_mirbug!(self, term, "call to converging function {:?} w/o dest", sig);
}

// When `unsized_fn_params` is not enabled,
// this check is done at `check_local`.
if self.unsized_feature_enabled() {
let span = term.source_info.span;
self.ensure_place_sized(dest_ty, span);
}
}
}
Expand Down
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