Reimplement code generation for copying fields in the

implicitly-generated copy constructor. Previously, Sema would perform
some checking and instantiation to determine which copy constructors,
etc., would be called, then CodeGen would attempt to figure out which
copy constructor to call... but would get it wrong, or poke at an
uninstantiated default argument, or fail in other ways.

The new scheme is similar to what we now do for the implicit
copy-assignment operator, where Sema performs all of the semantic
analysis and builds specific ASTs that look similar to the ASTs we'd
get from explicitly writing the copy constructor, so that CodeGen need
only do a direct translation.

However, it's not quite that simple because one cannot explicit write
elementwise copy-construction of an array. So, I've extended
CXXBaseOrMemberInitializer to contain a list of indexing variables
used to copy-construct the elements. For example, if we have:

  struct A { A(const A&); };
  
  struct B {
    A array[2][3];
  };

then we generate an implicit copy assignment operator for B that looks
something like this:

  B::B(const B &other) : array[i0][i1](other.array[i0][i1]) { }

CodeGen will loop over the invented variables i0 and i1 to visit all
elements in the array, so that each element in the destination array
will be copy-constructed from the corresponding element in the source
array. Of course, if we're dealing with arrays of scalars or class
types with trivial copy-assignment operators, we just generate a
memcpy rather than a loop.

Fixes PR6928, PR5989, and PR6887. Boost.Regex now compiles and passes
all of its regression tests.

Conspicuously missing from this patch is handling for the exceptional
case, where we need to destruct those objects that we have
constructed. I'll address that case separately.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@103079 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 96 insertions, 49 deletions

diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index b9c7d7948f..818a2bd446 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -1551,41 +1551,103 @@ BuildImplicitMemberInitializer(Sema &SemaRef, CXXConstructorDecl *Constructor,
                                FieldDecl *Field,
                                CXXBaseOrMemberInitializer *&CXXMemberInit) {
   if (ImplicitInitKind == IIK_Copy) {
-    // FIXME: We should not return early here, but will do so until 
-    // we know how to handle copy initialization of arrays.
-    CXXMemberInit = 0;
-    return false;
-    
+    SourceLocation Loc = Constructor->getLocation();
     ParmVarDecl *Param = Constructor->getParamDecl(0);
     QualType ParamType = Param->getType().getNonReferenceType();
     
     Expr *MemberExprBase = 
       DeclRefExpr::Create(SemaRef.Context, 0, SourceRange(), Param, 
-                          SourceLocation(), ParamType, 0);
+                          Loc, ParamType, 0);
+
+    // Build a reference to this field within the parameter.
+    CXXScopeSpec SS;
+    LookupResult MemberLookup(SemaRef, Field->getDeclName(), Loc,
+                              Sema::LookupMemberName);
+    MemberLookup.addDecl(Field, AS_public);
+    MemberLookup.resolveKind();
+    Sema::OwningExprResult CopyCtorArg 
+      = SemaRef.BuildMemberReferenceExpr(SemaRef.Owned(MemberExprBase),
+                                         ParamType, Loc,
+                                         /*IsArrow=*/false,
+                                         SS,
+                                         /*FirstQualifierInScope=*/0,
+                                         MemberLookup,
+                                         /*TemplateArgs=*/0);    
+    if (CopyCtorArg.isInvalid())
+      return true;
     
+    // When the field we are copying is an array, create index variables for 
+    // each dimension of the array. We use these index variables to subscript
+    // the source array, and other clients (e.g., CodeGen) will perform the
+    // necessary iteration with these index variables.
+    llvm::SmallVector<VarDecl *, 4> IndexVariables;
+    QualType BaseType = Field->getType();
+    QualType SizeType = SemaRef.Context.getSizeType();
+    while (const ConstantArrayType *Array
+                          = SemaRef.Context.getAsConstantArrayType(BaseType)) {
+      // Create the iteration variable for this array index.
+      IdentifierInfo *IterationVarName = 0;
+      {
+        llvm::SmallString<8> Str;
+        llvm::raw_svector_ostream OS(Str);
+        OS << "__i" << IndexVariables.size();
+        IterationVarName = &SemaRef.Context.Idents.get(OS.str());
+      }
+      VarDecl *IterationVar
+        = VarDecl::Create(SemaRef.Context, SemaRef.CurContext, Loc,
+                          IterationVarName, SizeType,
+                        SemaRef.Context.getTrivialTypeSourceInfo(SizeType, Loc),
+                          VarDecl::None, VarDecl::None);
+      IndexVariables.push_back(IterationVar);
+      
+      // Create a reference to the iteration variable.
+      Sema::OwningExprResult IterationVarRef
+        = SemaRef.BuildDeclRefExpr(IterationVar, SizeType, Loc);
+      assert(!IterationVarRef.isInvalid() &&
+             "Reference to invented variable cannot fail!");
+      
+      // Subscript the array with this iteration variable.
+      CopyCtorArg = SemaRef.CreateBuiltinArraySubscriptExpr(move(CopyCtorArg),
+                                                            Loc,
+                                                          move(IterationVarRef),
+                                                            Loc);
+      if (CopyCtorArg.isInvalid())
+        return true;
+      
+      BaseType = Array->getElementType();
+    }
     
-    Expr *CopyCtorArg = 
-      MemberExpr::Create(SemaRef.Context, MemberExprBase, /*IsArrow=*/false, 
-                         0, SourceRange(), Field, 
-                         DeclAccessPair::make(Field, Field->getAccess()),
-                         SourceLocation(), 0, 
-                         Field->getType().getNonReferenceType());
+    // Construct the entity that we will be initializing. For an array, this
+    // will be first element in the array, which may require several levels
+    // of array-subscript entities. 
+    llvm::SmallVector<InitializedEntity, 4> Entities;
+    Entities.reserve(1 + IndexVariables.size());
+    Entities.push_back(InitializedEntity::InitializeMember(Field));
+    for (unsigned I = 0, N = IndexVariables.size(); I != N; ++I)
+      Entities.push_back(InitializedEntity::InitializeElement(SemaRef.Context,
+                                                              0,
+                                                              Entities.back()));
     
-    InitializedEntity InitEntity = InitializedEntity::InitializeMember(Field);
+    // Direct-initialize to use the copy constructor.
     InitializationKind InitKind =
-      InitializationKind::CreateDirect(Constructor->getLocation(), 
-                                       SourceLocation(), SourceLocation());
+      InitializationKind::CreateDirect(Loc, SourceLocation(), SourceLocation());
     
-    InitializationSequence InitSeq(SemaRef, InitEntity, InitKind,
-                                   &CopyCtorArg, 1);
+    Expr *CopyCtorArgE = CopyCtorArg.takeAs<Expr>();
+    InitializationSequence InitSeq(SemaRef, Entities.back(), InitKind,
+                                   &CopyCtorArgE, 1);
     
-    Sema::OwningExprResult MemberInit =
-      InitSeq.Perform(SemaRef, InitEntity, InitKind, 
-                      Sema::MultiExprArg(SemaRef, (void**)&CopyCtorArg, 1), 0);
+    Sema::OwningExprResult MemberInit
+      = InitSeq.Perform(SemaRef, Entities.back(), InitKind, 
+                        Sema::MultiExprArg(SemaRef, (void**)&CopyCtorArgE, 1));
+    MemberInit = SemaRef.MaybeCreateCXXExprWithTemporaries(move(MemberInit));
     if (MemberInit.isInvalid())
       return true;
-    
-    CXXMemberInit = 0;
+
+    CXXMemberInit
+      = CXXBaseOrMemberInitializer::Create(SemaRef.Context, Field, Loc, Loc,
+                                           MemberInit.takeAs<Expr>(), Loc,
+                                           IndexVariables.data(),
+                                           IndexVariables.size());
     return false;
   }
 
@@ -1758,7 +1820,9 @@ Sema::SetBaseOrMemberInitializers(CXXConstructorDecl *Constructor,
           }
         }
       }
-      continue;
+      
+      if (ImplicitInitKind == IIK_Default)        
+        continue;
     }
     if (CXXBaseOrMemberInitializer *Value = AllBaseFields.lookup(*Field)) {
       AllToInit.push_back(Value);
@@ -4575,34 +4639,17 @@ void Sema::DefineImplicitCopyConstructor(SourceLocation CurrentLocation,
 
   if (SetBaseOrMemberInitializers(CopyConstructor, 0, 0, /*AnyErrors=*/false)) {
     Diag(CurrentLocation, diag::note_member_synthesized_at) 
-    << CXXCopyConstructor << Context.getTagDeclType(ClassDecl);
+      << CXXCopyConstructor << Context.getTagDeclType(ClassDecl);
     CopyConstructor->setInvalidDecl();
-  } else {
-    CopyConstructor->setUsed();
-  }
-
-  // FIXME: Once SetBaseOrMemberInitializers can handle copy initialization of
-  // fields, this code below should be removed.
-  for (CXXRecordDecl::field_iterator Field = ClassDecl->field_begin(),
-                                  FieldEnd = ClassDecl->field_end();
-       Field != FieldEnd; ++Field) {
-    QualType FieldType = Context.getCanonicalType((*Field)->getType());
-    if (const ArrayType *Array = Context.getAsArrayType(FieldType))
-      FieldType = Array->getElementType();
-    if (const RecordType *FieldClassType = FieldType->getAs<RecordType>()) {
-      CXXRecordDecl *FieldClassDecl
-        = cast<CXXRecordDecl>(FieldClassType->getDecl());
-      if (CXXConstructorDecl *FieldCopyCtor =
-          FieldClassDecl->getCopyConstructor(Context, TypeQuals)) {
-        CheckDirectMemberAccess(Field->getLocation(),
-                                FieldCopyCtor,
-                                PDiag(diag::err_access_copy_field)
-                                  << Field->getDeclName() << Field->getType());
-
-        MarkDeclarationReferenced(CurrentLocation, FieldCopyCtor);
-      }
-    }
+  }  else {
+    CopyConstructor->setBody(ActOnCompoundStmt(CopyConstructor->getLocation(),
+                                               CopyConstructor->getLocation(),
+                                               MultiStmtArg(*this, 0, 0), 
+                                               /*isStmtExpr=*/false)
+                                                              .takeAs<Stmt>());
   }
+  
+  CopyConstructor->setUsed();
 }
 
 Sema::OwningExprResult