[Clang] Fixes __builtin_is_implicit_lifetime for types with deleted ctrs

[cor3ntin]

We failed to check that the trivial constructor where eligible (this implies non deleted).

Fixes #160610

[llvmbot]

@llvm/pr-subscribers-clang

Author: Corentin Jabot (cor3ntin)

Changes

We failed to check that the trivial constructor where eligible (this implies non deleted).

Fixes #160610

---

Full diff: https://github.com/llvm/llvm-project/pull/161163.diff

3 Files Affected:

• (modified) clang/docs/ReleaseNotes.rst (+1)
• (modified) clang/lib/Sema/SemaTypeTraits.cpp (+10-7)
• (modified) clang/test/SemaCXX/type-traits.cpp (+40)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 270b5d336eba7..e8deae50e4cb0 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -432,6 +432,7 @@ Bug Fixes to C++ Support
 - Fix an assertion failure when taking the address on a non-type template parameter argument of
   object type. (#GH151531)
 - Suppress ``-Wdouble-promotion`` when explicitly asked for with C++ list initialization (#GH33409).
+- Fix the result of `__builtin_is_implicit_lifetime` for types with a user-provided constructor. (#GH160610)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaTypeTraits.cpp b/clang/lib/Sema/SemaTypeTraits.cpp
index c2427dcf52538..6c798d6acb0a0 100644
--- a/clang/lib/Sema/SemaTypeTraits.cpp
+++ b/clang/lib/Sema/SemaTypeTraits.cpp
@@ -1163,13 +1163,16 @@ static bool EvaluateUnaryTypeTrait(Sema &Self, TypeTrait UTT,
     //   - it has at least one trivial eligible constructor and a trivial,
     //     non-deleted destructor.
     const CXXDestructorDecl *Dtor = RD->getDestructor();
-    if (UnqualT->isAggregateType())
-      if (Dtor && !Dtor->isUserProvided())
-        return true;
-    if (RD->hasTrivialDestructor() && (!Dtor || !Dtor->isDeleted()))
-      if (RD->hasTrivialDefaultConstructor() ||
-          RD->hasTrivialCopyConstructor() || RD->hasTrivialMoveConstructor())
-        return true;
+    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;
+      }
+    }
     return false;
   }
   case UTT_IsIntangibleType:
diff --git a/clang/test/SemaCXX/type-traits.cpp b/clang/test/SemaCXX/type-traits.cpp
index 3f0124755c674..f8a88b1d0c0ad 100644
--- a/clang/test/SemaCXX/type-traits.cpp
+++ b/clang/test/SemaCXX/type-traits.cpp
@@ -2038,6 +2038,46 @@ void is_implicit_lifetime(int n) {
   static_assert(__builtin_is_implicit_lifetime(int * __restrict));
 }
 
+namespace GH160610 {
+class NonAggregate {
+public:
+    NonAggregate() = default;
+
+    NonAggregate(const NonAggregate&)            = delete;
+    NonAggregate& operator=(const NonAggregate&) = delete;
+private:
+    int num;
+};
+
+class DataMemberInitializer {
+public:
+    DataMemberInitializer() = default;
+
+    DataMemberInitializer(const DataMemberInitializer&)            = delete;
+    DataMemberInitializer& operator=(const DataMemberInitializer&) = delete;
+private:
+    int num = 0;
+};
+
+class UserProvidedConstructor {
+public:
+    UserProvidedConstructor() {}
+
+    UserProvidedConstructor(const UserProvidedConstructor&)            = delete;
+    UserProvidedConstructor& operator=(const UserProvidedConstructor&) = delete;
+};
+
+template <typename T>
+class Tpl {
+    Tpl() requires false = default ;
+};
+
+static_assert(__builtin_is_implicit_lifetime(NonAggregate));
+static_assert(!__builtin_is_implicit_lifetime(DataMemberInitializer));
+static_assert(!__builtin_is_implicit_lifetime(UserProvidedConstructor));
+static_assert(!__builtin_is_implicit_lifetime(Tpl<int>));
+}
+
 void is_signed()
 {
   //static_assert(__is_signed(char));

[shafik]

Might be worth adding a few more combinations here, like combinations of defaulted and deleted.

[bolshakov-a]

After this change, clang fails to detect implicitly defined trivial copy constructors. The assertion fails in this code:

struct S {
    S();
};

//S s1;

static_assert(__builtin_is_implicit_lifetime(S));

Uncomment s1 definition, and the code compiles, probably due to instantiation of the implicit S members.

[bolshakov-a]

@cor3ntin, what do you think?

[cor3ntin]

I will look into it, thanks for letting me know