PR46209: properly determine whether a copy assignment operator is

trivial.

We previously took a shortcut by assuming that if a subobject had a
trivial copy assignment operator (with a few side-conditions), we would
always invoke it, and could avoid going through overload resolution.
That turns out to not be correct in the presenve of ref-qualifiers (and
also won't be the case for copy-assignments with requires-clauses
either). Use the same logic for lazy declaration of copy-assignments
that we use for all other special member functions.

5 files changed, 35 insertions, 11 deletions

diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index a2a712e..8b96e20 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -2795,7 +2795,7 @@ ExpectedDecl ASTNodeImporter::VisitRecordDecl(RecordDecl *D) {
         return CDeclOrErr.takeError();
       D2CXX->setLambdaMangling(DCXX->getLambdaManglingNumber(), *CDeclOrErr,
                                DCXX->hasKnownLambdaInternalLinkage());
-    } else if (DCXX->isInjectedClassName()) {
+   } else if (DCXX->isInjectedClassName()) {
       // We have to be careful to do a similar dance to the one in
       // Sema::ActOnStartCXXMemberDeclarations
       const bool DelayTypeCreation = true;
diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp
index 4d184b5..6f1fd2f 100644
--- a/clang/lib/AST/DeclCXX.cpp
+++ b/clang/lib/AST/DeclCXX.cpp
@@ -84,10 +84,12 @@ CXXRecordDecl::DefinitionData::DefinitionData(CXXRecordDecl *D)
       HasInheritedConstructor(false), HasInheritedAssignment(false),
       NeedOverloadResolutionForCopyConstructor(false),
       NeedOverloadResolutionForMoveConstructor(false),
+      NeedOverloadResolutionForCopyAssignment(false),
       NeedOverloadResolutionForMoveAssignment(false),
       NeedOverloadResolutionForDestructor(false),
       DefaultedCopyConstructorIsDeleted(false),
       DefaultedMoveConstructorIsDeleted(false),
+      DefaultedCopyAssignmentIsDeleted(false),
       DefaultedMoveAssignmentIsDeleted(false),
       DefaultedDestructorIsDeleted(false), HasTrivialSpecialMembers(SMF_All),
       HasTrivialSpecialMembersForCall(SMF_All),
@@ -435,10 +437,8 @@ CXXRecordDecl::setBases(CXXBaseSpecifier const * const *Bases,
       setArgPassingRestrictions(RecordDecl::APK_CanNeverPassInRegs);
 
     // Keep track of the presence of mutable fields.
-    if (BaseClassDecl->hasMutableFields()) {
+    if (BaseClassDecl->hasMutableFields())
       data().HasMutableFields = true;
-      data().NeedOverloadResolutionForCopyConstructor = true;
-    }
 
     if (BaseClassDecl->hasUninitializedReferenceMember())
       data().HasUninitializedReferenceMember = true;
@@ -511,6 +511,8 @@ void CXXRecordDecl::addedClassSubobject(CXXRecordDecl *Subobj) {
   //    -- a direct or virtual base class B that cannot be copied/moved [...]
   //    -- a non-static data member of class type M (or array thereof)
   //        that cannot be copied or moved [...]
+  if (!Subobj->hasSimpleCopyAssignment())
+    data().NeedOverloadResolutionForCopyAssignment = true;
   if (!Subobj->hasSimpleMoveAssignment())
     data().NeedOverloadResolutionForMoveAssignment = true;
 
@@ -978,10 +980,8 @@ void CXXRecordDecl::addedMember(Decl *D) {
     }
 
     // Keep track of the presence of mutable fields.
-    if (Field->isMutable()) {
+    if (Field->isMutable())
       data().HasMutableFields = true;
-      data().NeedOverloadResolutionForCopyConstructor = true;
-    }
 
     // C++11 [class.union]p8, DR1460:
     //   If X is a union, a non-static data member of X that is not an anonymous
@@ -1025,10 +1025,12 @@ void CXXRecordDecl::addedMember(Decl *D) {
         if (isUnion()) {
           data().DefaultedCopyConstructorIsDeleted = true;
           data().DefaultedMoveConstructorIsDeleted = true;
+          data().DefaultedCopyAssignmentIsDeleted = true;
           data().DefaultedMoveAssignmentIsDeleted = true;
           data().DefaultedDestructorIsDeleted = true;
           data().NeedOverloadResolutionForCopyConstructor = true;
           data().NeedOverloadResolutionForMoveConstructor = true;
+          data().NeedOverloadResolutionForCopyAssignment = true;
           data().NeedOverloadResolutionForMoveAssignment = true;
           data().NeedOverloadResolutionForDestructor = true;
         }
@@ -1095,8 +1097,10 @@ void CXXRecordDecl::addedMember(Decl *D) {
     //   A defaulted copy/move assignment operator for a class X is defined
     //   as deleted if X has:
     //    -- a non-static data member of reference type
-    if (T->isReferenceType())
+    if (T->isReferenceType()) {
+      data().DefaultedCopyAssignmentIsDeleted = true;
       data().DefaultedMoveAssignmentIsDeleted = true;
+    }
 
     // Bitfields of length 0 are also zero-sized, but we already bailed out for
     // those because they are always unnamed.
@@ -1115,6 +1119,7 @@ void CXXRecordDecl::addedMember(Decl *D) {
           // parameter.
           data().NeedOverloadResolutionForCopyConstructor = true;
           data().NeedOverloadResolutionForMoveConstructor = true;
+          data().NeedOverloadResolutionForCopyAssignment = true;
           data().NeedOverloadResolutionForMoveAssignment = true;
         }
 
@@ -1128,6 +1133,8 @@ void CXXRecordDecl::addedMember(Decl *D) {
             data().DefaultedCopyConstructorIsDeleted = true;
           if (FieldRec->hasNonTrivialMoveConstructor())
             data().DefaultedMoveConstructorIsDeleted = true;
+          if (FieldRec->hasNonTrivialCopyAssignment())
+            data().DefaultedCopyAssignmentIsDeleted = true;
           if (FieldRec->hasNonTrivialMoveAssignment())
             data().DefaultedMoveAssignmentIsDeleted = true;
           if (FieldRec->hasNonTrivialDestructor())
@@ -1141,6 +1148,8 @@ void CXXRecordDecl::addedMember(Decl *D) {
               FieldRec->data().NeedOverloadResolutionForCopyConstructor;
           data().NeedOverloadResolutionForMoveConstructor |=
               FieldRec->data().NeedOverloadResolutionForMoveConstructor;
+          data().NeedOverloadResolutionForCopyAssignment |=
+              FieldRec->data().NeedOverloadResolutionForCopyAssignment;
           data().NeedOverloadResolutionForMoveAssignment |=
               FieldRec->data().NeedOverloadResolutionForMoveAssignment;
           data().NeedOverloadResolutionForDestructor |=
@@ -1238,9 +1247,15 @@ void CXXRecordDecl::addedMember(Decl *D) {
         }
 
         // Keep track of the presence of mutable fields.
-        if (FieldRec->hasMutableFields()) {
+        if (FieldRec->hasMutableFields())
           data().HasMutableFields = true;
+
+        if (Field->isMutable()) {
+          // Our copy constructor/assignment might call something other than
+          // the subobject's copy constructor/assignment if it's mutable and of
+          // class type.
           data().NeedOverloadResolutionForCopyConstructor = true;
+          data().NeedOverloadResolutionForCopyAssignment = true;
         }
 
         // C++11 [class.copy]p13:
@@ -1296,8 +1311,10 @@ void CXXRecordDecl::addedMember(Decl *D) {
       //   as deleted if X has:
       //    -- a non-static data member of const non-class type (or array
       //       thereof)
-      if (T.isConstQualified())
+      if (T.isConstQualified()) {
+        data().DefaultedCopyAssignmentIsDeleted = true;
         data().DefaultedMoveAssignmentIsDeleted = true;
+      }
     }
 
     // C++14 [meta.unary.prop]p4:
@@ -1382,6 +1399,9 @@ void CXXRecordDecl::setCaptures(ArrayRef<LambdaCapture> Captures) {
 
     *ToCapture++ = Captures[I];
   }
+
+  if (!lambdaIsDefaultConstructibleAndAssignable())
+    Data.DefaultedCopyAssignmentIsDeleted = true;
 }
 
 void CXXRecordDecl::setTrivialForCallFlags(CXXMethodDecl *D) {
diff --git a/clang/lib/AST/JSONNodeDumper.cpp b/clang/lib/AST/JSONNodeDumper.cpp
index 8edfed6..2f7aab0 100644
--- a/clang/lib/AST/JSONNodeDumper.cpp
+++ b/clang/lib/AST/JSONNodeDumper.cpp
@@ -386,6 +386,7 @@ static llvm::json::Object
 createCopyAssignmentDefinitionData(const CXXRecordDecl *RD) {
   llvm::json::Object Ret;
 
+  FIELD2("simple", hasSimpleCopyAssignment);
   FIELD2("trivial", hasTrivialCopyAssignment);
   FIELD2("nonTrivial", hasNonTrivialCopyAssignment);
   FIELD2("hasConstParam", hasCopyAssignmentWithConstParam);
diff --git a/clang/lib/AST/TextNodeDumper.cpp b/clang/lib/AST/TextNodeDumper.cpp
index 1e567e2..72f0ba3 100644
--- a/clang/lib/AST/TextNodeDumper.cpp
+++ b/clang/lib/AST/TextNodeDumper.cpp
@@ -1663,6 +1663,7 @@ void TextNodeDumper::VisitCXXRecordDecl(const CXXRecordDecl *D) {
         ColorScope Color(OS, ShowColors, DeclKindNameColor);
         OS << "CopyAssignment";
       }
+      FLAG(hasSimpleCopyAssignment, simple);
       FLAG(hasTrivialCopyAssignment, trivial);
       FLAG(hasNonTrivialCopyAssignment, non_trivial);
       FLAG(hasCopyAssignmentWithConstParam, has_const_param);
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index a137e6c..ed12b6c 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -13789,8 +13789,10 @@ CXXMethodDecl *Sema::DeclareImplicitCopyAssignment(CXXRecordDecl *ClassDecl) {
   Scope *S = getScopeForContext(ClassDecl);
   CheckImplicitSpecialMemberDeclaration(S, CopyAssignment);
 
-  if (ShouldDeleteSpecialMember(CopyAssignment, CXXCopyAssignment))
+  if (ShouldDeleteSpecialMember(CopyAssignment, CXXCopyAssignment)) {
+    ClassDecl->setImplicitCopyAssignmentIsDeleted();
     SetDeclDeleted(CopyAssignment, ClassLoc);
+  }
 
   if (S)
     PushOnScopeChains(CopyAssignment, S, false);