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[analyzer] StdVariantChecker: fix crashes and incorrect retrieval of template arguments #167341

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Merged
merged 2 commits into from
Nov 17, 2025
Merged

[analyzer] StdVariantChecker: fix crashes and incorrect retrieval of template arguments #167341

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e6a800f
StdVariantChecker: fix crash when argument to std::get is UnknownVal
guillem-bartrina-sonarsource Nov 10, 2025
14ef26c
StdVariantChecker: the variant template arguments are retrieved incor…
guillem-bartrina-sonarsource Nov 12, 2025
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13 changes: 9 additions & 4 deletions clang/lib/StaticAnalyzer/Checkers/StdVariantChecker.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -90,6 +90,9 @@ bool isStdVariant(const Type *Type) {
static std::optional<ArrayRef<TemplateArgument>>
getTemplateArgsFromVariant(const Type *VariantType) {
const auto *TempSpecType = VariantType->getAs<TemplateSpecializationType>();
while (TempSpecType && TempSpecType->isTypeAlias())
TempSpecType =
TempSpecType->getAliasedType()->getAs<TemplateSpecializationType>();
if (!TempSpecType)
return {};

Expand Down Expand Up @@ -219,10 +222,12 @@ class StdVariantChecker : public Checker<eval::Call, check::RegionChanges> {
bool handleStdGetCall(const CallEvent &Call, CheckerContext &C) const {
ProgramStateRef State = C.getState();

const auto &ArgType = Call.getArgSVal(0)
.getType(C.getASTContext())
->getPointeeType()
.getTypePtr();
SVal ArgSVal = Call.getArgSVal(0);
if (ArgSVal.isUnknown())
return false;

const auto &ArgType =
ArgSVal.getType(C.getASTContext())->getPointeeType().getTypePtr();
// We have to make sure that the argument is an std::variant.
// There is another std::get with std::pair argument
if (!isStdVariant(ArgType))
Expand Down
29 changes: 28 additions & 1 deletion clang/test/Analysis/std-variant-checker.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -355,4 +355,31 @@ void nonInlineFunctionCallPtr() {
char c = std::get<char> (v); // no-warning
(void)a;
(void)c;
}
}

// ----------------------------------------------------------------------------//
// Misc
// ----------------------------------------------------------------------------//

void unknownVal() {
// force the argument to be UnknownVal
(void)std::get<int>(*(std::variant<int, float>*)(int)3.14f); // no crash
}

template <typename T>
using MyVariant = std::variant<int, float>;

void typeAlias() {
MyVariant<bool> v;

(void)std::get<int>(v); // no-warning
}

template <template<typename> typename Container>
using MySpecialVariant = std::variant<int, float>;

void complexTypeAlias() {
MySpecialVariant<std::vector> v;

(void)std::get<int>(v); // no crash
}
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