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, 34 insertions, 15 deletions

diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
index 2ea1e6ff934..d68e4642fc4 100644
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -2310,23 +2310,42 @@ Sema::SubstituteExplicitTemplateArguments(
   // explicitly-specified template arguments. If the function has a trailing
   // return type, substitute it after the arguments to ensure we substitute
   // in lexical order.
-  if (Proto->hasTrailingReturn() &&
-      SubstParmTypes(Function->getLocation(),
-                     Function->param_begin(), Function->getNumParams(),
-                     MultiLevelTemplateArgumentList(*ExplicitArgumentList),
-                     ParamTypes))
-    return TDK_SubstitutionFailure;
-
+  if (Proto->hasTrailingReturn()) {
+    if (SubstParmTypes(Function->getLocation(),
+                       Function->param_begin(), Function->getNumParams(),
+                       MultiLevelTemplateArgumentList(*ExplicitArgumentList),
+                       ParamTypes))
+      return TDK_SubstitutionFailure;
+  }
+  
   // Instantiate the return type.
   // FIXME: exception-specifications?
-  QualType ResultType
-    = SubstType(Proto->getResultType(),
-                MultiLevelTemplateArgumentList(*ExplicitArgumentList),
-                Function->getTypeSpecStartLoc(),
-                Function->getDeclName());
-  if (ResultType.isNull() || Trap.hasErrorOccurred())
-    return TDK_SubstitutionFailure;
-
+  QualType ResultType;
+  {
+    // C++11 [expr.prim.general]p3:
+    //   If a declaration declares a member function or member function 
+    //   template of a class X, the expression this is a prvalue of type 
+    //   "pointer to cv-qualifier-seq X" between the optional cv-qualifer-seq
+    //   and the end of the function-definition, member-declarator, or 
+    //   declarator.
+    unsigned ThisTypeQuals = 0;
+    CXXRecordDecl *ThisContext = 0;
+    if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Function)) {
+      ThisContext = Method->getParent();
+      ThisTypeQuals = Method->getTypeQualifiers();
+    }
+      
+    CXXThisScopeRAII ThisScope(*this, ThisContext, ThisTypeQuals,
+                               getLangOpts().CPlusPlus0x);
+    
+    ResultType = SubstType(Proto->getResultType(),
+                   MultiLevelTemplateArgumentList(*ExplicitArgumentList),
+                   Function->getTypeSpecStartLoc(),
+                   Function->getDeclName());
+    if (ResultType.isNull() || Trap.hasErrorOccurred())
+      return TDK_SubstitutionFailure;
+  }
+  
   // Instantiate the types of each of the function parameters given the
   // explicitly-specified template arguments if we didn't do so earlier.
   if (!Proto->hasTrailingReturn() &&