Sema: Enforce C++11 pointer-to-member template arguments should rules

The standard is pretty clear on what it allows inside of template
arguments for non-type template parameters of pointer-to-member.

They must be of the form &qualified-id and cannot come from sources like
constexpr VarDecls or things of that nature.

This fixes PR18192.

llvm-svn: 196852

2 files changed, 9 insertions, 4 deletions

diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index d72c04c0121..20a3d283314 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -4584,9 +4584,7 @@ static bool CheckTemplateArgumentPointerToMember(Sema &S,
   else if ((DRE = dyn_cast<DeclRefExpr>(Arg))) {
     if (ValueDecl *VD = dyn_cast<ValueDecl>(DRE->getDecl())) {
       if (VD->getType()->isMemberPointerType()) {
-        if (isa<NonTypeTemplateParmDecl>(VD) ||
-            (isa<VarDecl>(VD) &&
-             S.Context.getCanonicalType(VD->getType()).isConstQualified())) {
+        if (isa<NonTypeTemplateParmDecl>(VD)) {
           if (Arg->isTypeDependent() || Arg->isValueDependent()) {
             Converted = TemplateArgument(Arg);
           } else {
diff --git a/clang/test/SemaTemplate/instantiate-member-pointers.cpp b/clang/test/SemaTemplate/instantiate-member-pointers.cpp
index 0db90e3cbf1..4757870d13b 100644
--- a/clang/test/SemaTemplate/instantiate-member-pointers.cpp
+++ b/clang/test/SemaTemplate/instantiate-member-pointers.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
 struct Y {
   int x;
 };
@@ -65,3 +65,10 @@ namespace ValueDepMemberPointer {
   }
   S<int> s; 
 }
+
+namespace PR18192 {
+  struct A { struct { int n; }; };
+  template<int A::*> struct X {};
+  constexpr int A::*p = &A::n;
+  X<p> x; // expected-error{{not a pointer to member constant}}
+}