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[dataflow] CXXOperatorCallExpr equal operator might not be a glvalue #80991

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Merged
merged 2 commits into from
Feb 13, 2024
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[dataflow] CXXOperatorCallExpr equal operator might not be a glvalue #80991

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0d03870
[dataflow] CXXOperatorCallExpr equal operator might not be a glvalue
paulsemel Feb 7, 2024
4165c1b
Update clang/lib/Analysis/FlowSensitive/Transfer.cpp
paulsemel Feb 8, 2024
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14 changes: 13 additions & 1 deletion clang/lib/Analysis/FlowSensitive/Transfer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -535,7 +535,19 @@ class TransferVisitor : public ConstStmtVisitor<TransferVisitor> {
return;

copyRecord(*LocSrc, *LocDst, Env);
Env.setStorageLocation(*S, *LocDst);

// If the expr is a glvalue, we can reasonably assume the operator is
// returning T& and thus we can assign it `LocDst`.
if (S->isGLValue()) {
Env.setStorageLocation(*S, *LocDst);
} else if (S->getType()->isRecordType()) {
// Make sure that we have a `RecordValue` for this expression so that
// `Environment::getResultObjectLocation()` is able to return a location
// for it.
if (Env.getValue(*S) == nullptr)
refreshRecordValue(*S, Env);
Comment on lines +547 to +548
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Is this actually necessary? (It's not really doing anything?)

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Yes, similarly to TransferCallExpr, it ensures a RecordValue exists. This is just a short path for not having to call TransferCallExpr, since it is pretty much the only thing that will trigger if being called.

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Got it. Added a suggested edit for the comment.

}

return;
}

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36 changes: 36 additions & 0 deletions clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
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Expand Up @@ -2313,6 +2313,42 @@ TEST(TransferTest, AssignmentOperatorWithInitAndInheritance) {
ASTContext &ASTCtx) {});
}

TEST(TransferTest, AssignmentOperatorReturnsVoid) {
// This is a crash repro.
std::string Code = R"(
struct S {
void operator=(S&& other);
};
void target() {
S s;
s = S();
// [[p]]
}
)";
runDataflow(
Code,
[](const llvm::StringMap<DataflowAnalysisState<NoopLattice>> &Results,
ASTContext &ASTCtx) {});
}

TEST(TransferTest, AssignmentOperatorReturnsByValue) {
// This is a crash repro.
std::string Code = R"(
struct S {
S operator=(S&& other);
};
void target() {
S s;
s = S();
// [[p]]
}
)";
runDataflow(
Code,
[](const llvm::StringMap<DataflowAnalysisState<NoopLattice>> &Results,
ASTContext &ASTCtx) {});
}

TEST(TransferTest, CopyConstructor) {
std::string Code = R"(
struct A {
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