[clang] [Clang] Fix a regression introduced by #161163. (PR #162612)

[Corentin Jabot via cfe-commits]

https://github.com/cor3ntin updated https://github.com/llvm/llvm-project/pull/162612

>From af13d31f970cc62d46746b5e57075f16c5f5c4e8 Mon Sep 17 00:00:00 2001
From: Corentin Jabot <corentinjabot at gmail.com>
Date: Thu, 9 Oct 2025 10:18:28 +0200
Subject: [PATCH 1/2] [Clang] Fix a regression introduced by #161163.

Classes with a user provided constructor are still implicit lifetime
if they have an implicit, trivial copy ctr.
---
 clang/lib/Sema/SemaTypeTraits.cpp  | 24 +++++++++++++++++-------
 clang/test/SemaCXX/type-traits.cpp | 12 +++++++++++-
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/clang/lib/Sema/SemaTypeTraits.cpp b/clang/lib/Sema/SemaTypeTraits.cpp
index 3e34675cbf064..13f25c453d8ba 100644
--- a/clang/lib/Sema/SemaTypeTraits.cpp
+++ b/clang/lib/Sema/SemaTypeTraits.cpp
@@ -1165,14 +1165,24 @@ 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;
+    bool FoundCopyCtr = false;
+    bool FoundMoveCtr = false;
+    for (CXXConstructorDecl *Ctr : RD->ctors()) {
+      FoundCopyCtr = Ctr->isCopyConstructor();
+      FoundMoveCtr = Ctr->isMoveConstructor();
+      if (Ctr->isIneligibleOrNotSelected() || Ctr->isDeleted())
+        continue;
+      if (Ctr->isTrivial())
+        return true;
     }
+    if (!FoundCopyCtr && RD->hasTrivialCopyConstructor() &&
+        !RD->defaultedCopyConstructorIsDeleted())
+      return true;
+    if (!FoundMoveCtr && RD->hasTrivialMoveConstructor() &&
+        !RD->defaultedMoveConstructorIsDeleted())
+      return true;
     return false;
   }
   case UTT_IsIntangibleType:
diff --git a/clang/test/SemaCXX/type-traits.cpp b/clang/test/SemaCXX/type-traits.cpp
index 901d510bba847..343529fe81b57 100644
--- a/clang/test/SemaCXX/type-traits.cpp
+++ b/clang/test/SemaCXX/type-traits.cpp
@@ -2066,7 +2066,17 @@ class UserProvidedConstructor {
     UserProvidedConstructor(const UserProvidedConstructor&)            = delete;
     UserProvidedConstructor& operator=(const UserProvidedConstructor&) = delete;
 };
+struct Ctr {
+    Ctr();
+};
+struct Ctr2 {
+    Ctr2();
+private:
+  NoEligibleTrivialContructor inner;
+};
 
+static_assert(__builtin_is_implicit_lifetime(Ctr));
+static_assert(!__builtin_is_implicit_lifetime(NoEligibleTrivialContructor));
 static_assert(__builtin_is_implicit_lifetime(NonAggregate));
 static_assert(!__builtin_is_implicit_lifetime(DataMemberInitializer));
 static_assert(!__builtin_is_implicit_lifetime(UserProvidedConstructor));
@@ -2076,7 +2086,7 @@ 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
 }

>From 32f2664975e61c3368a4d47a10bb992c2572edd5 Mon Sep 17 00:00:00 2001
From: Corentin Jabot <corentinjabot at gmail.com>
Date: Thu, 9 Oct 2025 18:24:41 +0200
Subject: [PATCH 2/2] fix the case of non copyable subobjects

---
 clang/lib/Sema/SemaTypeTraits.cpp  | 10 ++++++++--
 clang/test/SemaCXX/type-traits.cpp | 10 ++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Sema/SemaTypeTraits.cpp b/clang/lib/Sema/SemaTypeTraits.cpp
index 13f25c453d8ba..187d39e8f26ed 100644
--- a/clang/lib/Sema/SemaTypeTraits.cpp
+++ b/clang/lib/Sema/SemaTypeTraits.cpp
@@ -1167,16 +1167,22 @@ static bool EvaluateUnaryTypeTrait(Sema &Self, TypeTrait UTT,
       return true;
     if (!(RD->hasTrivialDestructor() && (!Dtor || !Dtor->isDeleted())))
       return false;
+    if (RD->hasTrivialDefaultConstructor())
+      return true;
     bool FoundCopyCtr = false;
     bool FoundMoveCtr = false;
+    bool FoundDefaultCtr = false;
     for (CXXConstructorDecl *Ctr : RD->ctors()) {
-      FoundCopyCtr = Ctr->isCopyConstructor();
-      FoundMoveCtr = Ctr->isMoveConstructor();
       if (Ctr->isIneligibleOrNotSelected() || Ctr->isDeleted())
         continue;
       if (Ctr->isTrivial())
         return true;
+      FoundCopyCtr = Ctr->isCopyConstructor();
+      FoundMoveCtr = Ctr->isMoveConstructor();
+      FoundDefaultCtr = Ctr->isDefaultConstructor();
     }
+    if (!FoundDefaultCtr && RD->hasTrivialDefaultConstructor())
+      return true;
     if (!FoundCopyCtr && RD->hasTrivialCopyConstructor() &&
         !RD->defaultedCopyConstructorIsDeleted())
       return true;
diff --git a/clang/test/SemaCXX/type-traits.cpp b/clang/test/SemaCXX/type-traits.cpp
index 343529fe81b57..bc010dc5932ca 100644
--- a/clang/test/SemaCXX/type-traits.cpp
+++ b/clang/test/SemaCXX/type-traits.cpp
@@ -2075,7 +2075,17 @@ struct Ctr2 {
   NoEligibleTrivialContructor inner;
 };
 
+struct NonCopyable{
+    NonCopyable() = default;
+    NonCopyable(const NonCopyable&) = delete;
+};
+
+class C {
+    NonCopyable nc;
+};
+
 static_assert(__builtin_is_implicit_lifetime(Ctr));
+static_assert(__builtin_is_implicit_lifetime(C));
 static_assert(!__builtin_is_implicit_lifetime(NoEligibleTrivialContructor));
 static_assert(__builtin_is_implicit_lifetime(NonAggregate));
 static_assert(!__builtin_is_implicit_lifetime(DataMemberInitializer));