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[clang] Refactor: Introduce a new LifetimeKind for the assignment case, NFC #99005

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Jul 16, 2024
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[clang] Refactor: Introduce a new LifetimeKind for the assignment case, NFC #99005

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39 changes: 23 additions & 16 deletions clang/lib/Sema/CheckExprLifetime.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,11 @@ enum LifetimeKind {
/// This is a mem-initializer: if it would extend a temporary (other than via
/// a default member initializer), the program is ill-formed.
LK_MemInitializer,

/// The lifetime of a temporary bound to this entity probably ends too soon,
/// because the entity is a pointer and we assign the address of a temporary
/// object to it.
LK_Assignment,
};
using LifetimeResult =
llvm::PointerIntPair<const InitializedEntity *, 3, LifetimeKind>;
Expand Down Expand Up @@ -971,6 +976,8 @@ static void checkExprLifetimeImpl(Sema &SemaRef,
const InitializedEntity *ExtendingEntity,
LifetimeKind LK,
const AssignedEntity *AEntity, Expr *Init) {
assert((AEntity && LK == LK_Assignment) ||
(InitEntity && LK != LK_Assignment));
// If this entity doesn't have an interesting lifetime, don't bother looking
// for temporaries within its initializer.
if (LK == LK_FullExpression)
Expand Down Expand Up @@ -1008,19 +1015,7 @@ static void checkExprLifetimeImpl(Sema &SemaRef,
return true;
}
}
if (AEntity) {
if (!MTE)
return false;
assert(shouldLifetimeExtendThroughPath(Path) ==
PathLifetimeKind::NoExtend &&
"No lifetime extension for assignments");
if (!pathContainsInit(Path))
SemaRef.Diag(DiagLoc, diag::warn_dangling_pointer_assignment)
<< AEntity->LHS << DiagRange;
return false;
}

assert(InitEntity && "only for initialization");
switch (LK) {
case LK_FullExpression:
llvm_unreachable("already handled this");
Expand Down Expand Up @@ -1077,6 +1072,17 @@ static void checkExprLifetimeImpl(Sema &SemaRef,
break;
}

case LK_Assignment: {
if (!MTE)
return false;
assert(shouldLifetimeExtendThroughPath(Path) ==
PathLifetimeKind::NoExtend &&
"No lifetime extension for assignments");
if (!pathContainsInit(Path))
SemaRef.Diag(DiagLoc, diag::warn_dangling_pointer_assignment)
<< AEntity->LHS << DiagRange;
return false;
}
case LK_MemInitializer: {
if (MTE) {
// Under C++ DR1696, if a mem-initializer (or a default member
Expand Down Expand Up @@ -1283,10 +1289,11 @@ void checkExprLifetime(Sema &SemaRef, const InitializedEntity &Entity,

void checkExprLifetime(Sema &SemaRef, const AssignedEntity &Entity,
Expr *Init) {
LifetimeKind LK = LK_FullExpression;
if (Entity.LHS->getType()->isPointerType()) // builtin pointer type
LK = LK_Extended;
checkExprLifetimeImpl(SemaRef, nullptr, nullptr, LK, &Entity, Init);
if (!Entity.LHS->getType()->isPointerType()) // builtin pointer type
return;
checkExprLifetimeImpl(SemaRef, /*InitEntity=*/nullptr,
/*ExtendingEntity=*/nullptr, LK_Assignment, &Entity,
Init);
}

} // namespace clang::sema