Implement C++11 [expr.prim.general]p3, which permits the use of 'this'

in the declaration of a non-static member function after the
(optional) cv-qualifier-seq, which in practice means in the exception
specification and late-specified return type. 

The new scheme here used to manage 'this' outside of a member function
scope is more general than the Scope-based mechanism previously used
for non-static data member initializers and late-parsesd attributes,
because it can also handle the cv-qualifiers on the member
function. Note, however, that a separate pass is required for static
member functions to determine whether 'this' was used, because we
might not know that we have a static function until after declaration
matching.

Finally, this introduces name mangling for 'this' and for the implicit
'this', which is intended to match GCC's mangling. Independent
verification for the new mangling test case would be appreciated.

Fixes PR10036 and PR12450.

llvm-svn: 154799

1 files changed, 51 insertions, 18 deletions

diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index 4740145fd5a..60de75b9172 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -789,6 +789,11 @@ namespace {
     
     QualType TransformFunctionProtoType(TypeLocBuilder &TLB,
                                         FunctionProtoTypeLoc TL);
+    QualType TransformFunctionProtoType(TypeLocBuilder &TLB,
+                                        FunctionProtoTypeLoc TL,
+                                        CXXRecordDecl *ThisContext,
+                                        unsigned ThisTypeQuals);
+
     ParmVarDecl *TransformFunctionTypeParam(ParmVarDecl *OldParm,
                                             int indexAdjustment,
                                         llvm::Optional<unsigned> NumExpansions,
@@ -1211,6 +1216,16 @@ QualType TemplateInstantiator::TransformFunctionProtoType(TypeLocBuilder &TLB,
   return inherited::TransformFunctionProtoType(TLB, TL);
 }
 
+QualType TemplateInstantiator::TransformFunctionProtoType(TypeLocBuilder &TLB,
+                                 FunctionProtoTypeLoc TL,
+                                 CXXRecordDecl *ThisContext,
+                                 unsigned ThisTypeQuals) {
+  // We need a local instantiation scope for this function prototype.
+  LocalInstantiationScope Scope(SemaRef, /*CombineWithOuterScope=*/true);
+  return inherited::TransformFunctionProtoType(TLB, TL, ThisContext, 
+                                               ThisTypeQuals);  
+}
+
 ParmVarDecl *
 TemplateInstantiator::TransformFunctionTypeParam(ParmVarDecl *OldParm,
                                                  int indexAdjustment,
@@ -1446,7 +1461,9 @@ static bool NeedsInstantiationAsFunctionType(TypeSourceInfo *T) {
 TypeSourceInfo *Sema::SubstFunctionDeclType(TypeSourceInfo *T,
                                 const MultiLevelTemplateArgumentList &Args,
                                 SourceLocation Loc,
-                                DeclarationName Entity) {
+                                DeclarationName Entity,
+                                CXXRecordDecl *ThisContext,
+                                unsigned ThisTypeQuals) {
   assert(!ActiveTemplateInstantiations.empty() &&
          "Cannot perform an instantiation without some context on the "
          "instantiation stack");
@@ -1461,7 +1478,14 @@ TypeSourceInfo *Sema::SubstFunctionDeclType(TypeSourceInfo *T,
   TypeLoc TL = T->getTypeLoc();
   TLB.reserve(TL.getFullDataSize());
 
-  QualType Result = Instantiator.TransformType(TLB, TL);
+  QualType Result;
+  
+  if (FunctionProtoTypeLoc *Proto = dyn_cast<FunctionProtoTypeLoc>(&TL)) {
+    Result = Instantiator.TransformFunctionProtoType(TLB, *Proto, ThisContext,
+                                                     ThisTypeQuals);
+  } else {
+    Result = Instantiator.TransformType(TLB, TL);
+  }
   if (Result.isNull())
     return 0;
 
@@ -1878,24 +1902,33 @@ Sema::InstantiateClass(SourceLocation PointOfInstantiation,
   CheckCompletedCXXClass(Instantiation);
 
   // Attach any in-class member initializers now the class is complete.
-  for (unsigned I = 0, N = FieldsWithMemberInitializers.size(); I != N; ++I) {
-    FieldDecl *OldField = FieldsWithMemberInitializers[I].first;
-    FieldDecl *NewField = FieldsWithMemberInitializers[I].second;
-    Expr *OldInit = OldField->getInClassInitializer();
-
-    ExprResult NewInit = SubstInitializer(OldInit, TemplateArgs,
-                                          /*CXXDirectInit=*/false);
-    if (NewInit.isInvalid())
-      NewField->setInvalidDecl();
-    else {
-      Expr *Init = NewInit.take();
-      assert(Init && "no-argument initializer in class");
-      assert(!isa<ParenListExpr>(Init) && "call-style init in class");
-      ActOnCXXInClassMemberInitializer(NewField,
-                                       Init->getSourceRange().getBegin(), Init);
+  {
+    // C++11 [expr.prim.general]p4:
+    //   Otherwise, if a member-declarator declares a non-static data member 
+    //  (9.2) of a class X, the expression this is a prvalue of type "pointer
+    //  to X" within the optional brace-or-equal-initializer. It shall not 
+    //  appear elsewhere in the member-declarator.
+    CXXThisScopeRAII ThisScope(*this, Instantiation, (unsigned)0);
+    
+    for (unsigned I = 0, N = FieldsWithMemberInitializers.size(); I != N; ++I) {
+      FieldDecl *OldField = FieldsWithMemberInitializers[I].first;
+      FieldDecl *NewField = FieldsWithMemberInitializers[I].second;
+      Expr *OldInit = OldField->getInClassInitializer();
+
+      ExprResult NewInit = SubstInitializer(OldInit, TemplateArgs,
+                                            /*CXXDirectInit=*/false);
+      if (NewInit.isInvalid())
+        NewField->setInvalidDecl();
+      else {
+        Expr *Init = NewInit.take();
+        assert(Init && "no-argument initializer in class");
+        assert(!isa<ParenListExpr>(Init) && "call-style init in class");
+        ActOnCXXInClassMemberInitializer(NewField, 
+                                         Init->getSourceRange().getBegin(), 
+                                         Init);
+      }
     }
   }
-
   // Instantiate late parsed attributes, and attach them to their decls.
   // See Sema::InstantiateAttrs
   for (LateInstantiatedAttrVec::iterator I = LateAttrs.begin(),