From 4b50263096457552ee86eb790c9638c6bb7357fa Mon Sep 17 00:00:00 2001
From: John McCall <rjmccall@apple.com>
Date: Tue, 15 May 2012 02:01:59 +0000
Subject: [PATCH] Change the mangling of a ref-qualifier on a function type so
 that it is placed in a position which is never ambiguous with a
 reference-to-function type.  This follows some recent discussion and ensuing
 proposal on cxx-abi-dev.  It is not necessary to change the mangling of
 CV-qualifiers because you cannot apply CV-qualification in the normal sense
 to a function type. It is not necessary to change the mangling of
 ref-qualifiers on method declarations because they appear in an unambiguous
 location.

In addition, mangle CV-qualifiers and ref-qualifiers on function
types when they occur in positions other than member pointers
(that is, when they appear as template arguments).

This is a minor ABI break with previous releases of clang.  It
is not considered critical because (1) ref-qualifiers are
relatively rare, since AFAIK we're the only implementing compiler,
and (2) they're particularly likely to come up in contexts that
do not rely on the ODR for correctness.  We apologize for any
inconvenience;  this is the right thing to do.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@156794 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/AST/ItaniumMangle.cpp                 | 21 ++++++++++++++++-----
 test/CodeGenCXX/mangle-ref-qualifiers.cpp |  8 +++++++-
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/lib/AST/ItaniumMangle.cpp b/lib/AST/ItaniumMangle.cpp
index 88c253d450..250bcf972c 100644
--- a/lib/AST/ItaniumMangle.cpp
+++ b/lib/AST/ItaniumMangle.cpp
@@ -1892,12 +1892,23 @@ void CXXNameMangler::mangleType(const BuiltinType *T) {
 }
 
 // <type>          ::= <function-type>
-// <function-type> ::= F [Y] <bare-function-type> E
+// <function-type> ::= [<CV-qualifiers>] F [Y]
+//                      <bare-function-type> [<ref-qualifier>] E
+// (Proposal to cxx-abi-dev, 2012-05-11)
 void CXXNameMangler::mangleType(const FunctionProtoType *T) {
+  // Mangle CV-qualifiers, if present.  These are 'this' qualifiers,
+  // e.g. "const" in "int (A::*)() const".
+  mangleQualifiers(Qualifiers::fromCVRMask(T->getTypeQuals()));
+
   Out << 'F';
+
   // FIXME: We don't have enough information in the AST to produce the 'Y'
   // encoding for extern "C" function types.
   mangleBareFunctionType(T, /*MangleReturnType=*/true);
+
+  // Mangle the ref-qualifier, if present.
+  mangleRefQualifier(T->getRefQualifier());
+
   Out << 'E';
 }
 void CXXNameMangler::mangleType(const FunctionNoProtoType *T) {
@@ -1990,8 +2001,6 @@ void CXXNameMangler::mangleType(const MemberPointerType *T) {
   mangleType(QualType(T->getClass(), 0));
   QualType PointeeType = T->getPointeeType();
   if (const FunctionProtoType *FPT = dyn_cast<FunctionProtoType>(PointeeType)) {
-    mangleQualifiers(Qualifiers::fromCVRMask(FPT->getTypeQuals()));
-    mangleRefQualifier(FPT->getRefQualifier());
     mangleType(FPT);
     
     // Itanium C++ ABI 5.1.8:
@@ -2005,9 +2014,11 @@ void CXXNameMangler::mangleType(const MemberPointerType *T) {
     //   which the function is a member is considered part of the type of 
     //   function.
 
+    // Given that we already substitute member function pointers as a
+    // whole, the net effect of this rule is just to unconditionally
+    // suppress substitution on the function type in a member pointer.
     // We increment the SeqID here to emulate adding an entry to the
-    // substitution table. We can't actually add it because we don't want this
-    // particular function type to be substituted.
+    // substitution table.
     ++SeqID;
   } else
     mangleType(PointeeType);
diff --git a/test/CodeGenCXX/mangle-ref-qualifiers.cpp b/test/CodeGenCXX/mangle-ref-qualifiers.cpp
index 568cf9f247..ce2af502e4 100644
--- a/test/CodeGenCXX/mangle-ref-qualifiers.cpp
+++ b/test/CodeGenCXX/mangle-ref-qualifiers.cpp
@@ -12,5 +12,11 @@ int X::g() && { return 0; }
 // CHECK: define i32 @_ZNKO1X1hEv
 int X::h() const && { return 0; }
 
-// CHECK: define void @_Z1fM1XRFivEMS_OFivEMS_KOFivE
+// CHECK: define void @_Z1fM1XFivREMS_FivOEMS_KFivOE
 void f(int (X::*)() &, int (X::*)() &&, int (X::*)() const&&) { }
+
+// CHECK: define void @_Z1g1AIFivEES_IFivREES_IFivOEES_IKFivEES_IKFivREES_IKFivOEES_IVKFivEES_IVKFivREES_IVKFivOEE()
+template <class T> struct A {};
+void g(A<int()>, A<int()&>, A<int()&&>,
+       A<int() const>, A<int() const &>, A<int() const &&>,
+       A<int() const volatile>, A<int() const volatile &>, A<int() const volatile &&>) {}
-- 
2.40.0