ms-compat: Fix taking the address of a member of a dependent base

If unqualified id lookup fails while parsing a class template with a
dependent base, clang with -fms-compatibility will pretend the user
prefixed the name with 'this->' in order to delay the lookup.  However,
if there was a unary ampersand, Sema::ActOnDependentIdExpression() will
create a DependentDeclRefExpr, which is not what we wanted at all.  Fix
this by building the CXXDependentScopeMemberExpr directly instead.

In order to be fully MSVC compatible, we would have to defer all
attempts at name lookup to instantiation time.  However, until we have
real problems with system headers that can't be parsed, we'll put off
implementing that.

Fixes PR16014.

Reviewers: rsmith

Differential Revision: http://llvm-reviews.chandlerc.com/D1892

llvm-svn: 192727

1 files changed, 40 insertions, 0 deletions

diff --git a/clang/test/SemaTemplate/ms-lookup-template-base-classes.cpp b/clang/test/SemaTemplate/ms-lookup-template-base-classes.cpp
index cb1a7f50b71..72ce056063e 100644
--- a/clang/test/SemaTemplate/ms-lookup-template-base-classes.cpp
+++ b/clang/test/SemaTemplate/ms-lookup-template-base-classes.cpp
@@ -196,3 +196,43 @@ void f() {
 }
 
 }  // namespace PR12701
+
+namespace PR16014 {
+
+struct A {
+  int a;
+  static int sa;
+};
+template <typename T> struct B : T {
+  int     foo() { return a; }
+  int    *bar() { return &a; }
+  int     baz() { return T::a; }
+  int T::*qux() { return &T::a; }
+  static int T::*stuff() { return &T::a; }
+  static int stuff1() { return T::sa; }
+  static int *stuff2() { return &T::sa; }
+};
+
+template <typename T> struct C : T {
+  int     foo() { return b; }      // expected-error {{no member named 'b' in 'PR16014::C<PR16014::A>'}}
+  int    *bar() { return &b; }     // expected-error {{no member named 'b' in 'PR16014::C<PR16014::A>'}}
+  int     baz() { return T::b; }   // expected-error {{no member named 'b' in 'PR16014::A'}}
+  int T::*qux() { return &T::b; }  // expected-error {{no member named 'b' in 'PR16014::A'}}
+  int T::*fuz() { return &U::a; }  // expected-error {{use of undeclared identifier 'U'}}
+};
+
+template struct B<A>;
+template struct C<A>;  // expected-note-re 1+ {{in instantiation of member function 'PR16014::C<PR16014::A>::.*' requested here}}
+
+template <typename T> struct D : T {
+  struct Inner {
+    int foo() {
+      // FIXME: MSVC can find this in D's base T!  Even worse, if ::sa exists,
+      // clang will use it instead.
+      return sa; // expected-error {{use of undeclared identifier 'sa'}}
+    }
+  };
+};
+template struct D<A>;
+
+}