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[Clang] Fix a regression introduced by #161163. #162612

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[Clang] Fix a regression introduced by #161163. #162612

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af13d31
[Clang] Fix a regression introduced by #161163.
cor3ntin Oct 9, 2025
32f2664
fix the case of non copyable subobjects
cor3ntin Oct 9, 2025
189c4a1
more fixes + cleanup + add missing tests
cor3ntin Oct 10, 2025
8dd01f8
more tests for constrained default constructors
cor3ntin Oct 10, 2025
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30 changes: 23 additions & 7 deletions clang/lib/Sema/SemaTypeTraits.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1165,14 +1165,30 @@ static bool EvaluateUnaryTypeTrait(Sema &Self, TypeTrait UTT,
const CXXDestructorDecl *Dtor = RD->getDestructor();
if (UnqualT->isAggregateType() && (!Dtor || !Dtor->isUserProvided()))
return true;
if (RD->hasTrivialDestructor() && (!Dtor || !Dtor->isDeleted())) {
for (CXXConstructorDecl *Ctr : RD->ctors()) {
if (Ctr->isIneligibleOrNotSelected() || Ctr->isDeleted())
continue;
if (Ctr->isTrivial())
return true;
}
if (!(RD->hasTrivialDestructor() && (!Dtor || !Dtor->isDeleted())))
return false;
if (RD->hasTrivialDefaultConstructor())
return true;
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UTT_HasTrivialDefaultConstructor handler checks RD->hasTrivialDefaultConstructor() && !RD->hasNonTrivialDefaultConstructor() for some reason. Not sure if this is really needed.

bool FoundCopyCtr = false;
bool FoundMoveCtr = false;
bool FoundDefaultCtr = false;
for (CXXConstructorDecl *Ctr : RD->ctors()) {
if (Ctr->isIneligibleOrNotSelected() || Ctr->isDeleted())
continue;
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The test fails now because short-circuiting here occurs before FoundCopyCtr can be set.

if (Ctr->isTrivial())
return true;
FoundCopyCtr = Ctr->isCopyConstructor();
FoundMoveCtr = Ctr->isMoveConstructor();
FoundDefaultCtr = Ctr->isDefaultConstructor();
}
if (!FoundDefaultCtr && RD->hasTrivialDefaultConstructor())
return true;
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This is never reached because RD->hasTrivialDefaultConstructor() == true case has been short-circuited above.

if (!FoundCopyCtr && RD->hasTrivialCopyConstructor() &&
!RD->defaultedCopyConstructorIsDeleted())
return true;
if (!FoundMoveCtr && RD->hasTrivialMoveConstructor() &&
!RD->defaultedMoveConstructorIsDeleted())
return true;
return false;
}
case UTT_IsIntangibleType:
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22 changes: 21 additions & 1 deletion clang/test/SemaCXX/type-traits.cpp
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Expand Up @@ -2066,7 +2066,27 @@ class UserProvidedConstructor {
UserProvidedConstructor(const UserProvidedConstructor&) = delete;
UserProvidedConstructor& operator=(const UserProvidedConstructor&) = delete;
};
struct Ctr {
Ctr();
};
struct Ctr2 {
Ctr2();
private:
NoEligibleTrivialContructor inner;
};

struct NonCopyable{
NonCopyable() = default;
NonCopyable(const NonCopyable&) = delete;
};

class C {
NonCopyable nc;
};
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It would be good to add a note that the classes should not be used here in any way causing declarations of the implicit methods to be instantiated (or whatever the correct word is).


static_assert(__builtin_is_implicit_lifetime(Ctr));
static_assert(__builtin_is_implicit_lifetime(C));
static_assert(!__builtin_is_implicit_lifetime(NoEligibleTrivialContructor));
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Ctr2 is not used in this test. Maybe, you wanted to mention it here instead of NoEligibleTrivialContructor?

static_assert(__builtin_is_implicit_lifetime(NonAggregate));
static_assert(!__builtin_is_implicit_lifetime(DataMemberInitializer));
static_assert(!__builtin_is_implicit_lifetime(UserProvidedConstructor));
Expand All @@ -2076,7 +2096,7 @@ template <typename T>
class Tpl {
Tpl() requires false = default ;
};
static_assert(!__builtin_is_implicit_lifetime(Tpl<int>));
static_assert(__builtin_is_implicit_lifetime(Tpl<int>));

#endif
}
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