MS ABI: Add support for #pragma pointers_to_members

Introduce a notion of a 'current representation method' for
pointers-to-members.

When starting out, this is set to 'best case' (representation method is
chosen by examining the class, selecting the smallest representation
that would work given the class definition or lack thereof).

This pragma allows the translation unit to dictate exactly what
representation to use, similar to how the inheritance model keywords
operate.

N.B.  PCH support is forthcoming.

Differential Revision: http://llvm-reviews.chandlerc.com/D2723

llvm-svn: 201105

1 files changed, 23 insertions, 0 deletions

diff --git a/clang/test/SemaCXX/member-pointer-ms.cpp b/clang/test/SemaCXX/member-pointer-ms.cpp
index 8e8094004f6..422b7cfbd18 100644
--- a/clang/test/SemaCXX/member-pointer-ms.cpp
+++ b/clang/test/SemaCXX/member-pointer-ms.cpp
@@ -202,3 +202,26 @@ struct __multiple_inheritance C {}; // expected-error{{inheritance model does no
 struct __virtual_inheritance D;
 struct D : virtual B {};
 }
+
+#pragma pointers_to_members(full_generality, multiple_inheritance)
+struct TrulySingleInheritance;
+static_assert(sizeof(int TrulySingleInheritance::*) == kMultipleDataSize, "");
+#pragma pointers_to_members(best_case)
+// This definition shouldn't conflict with the increased generality that the
+// multiple_inheritance model gave to TrulySingleInheritance.
+struct TrulySingleInheritance {};
+
+// Even if a definition proceeds the first mention of a pointer to member, we
+// still give the record the fully general representation.
+#pragma pointers_to_members(full_generality, virtual_inheritance)
+struct SingleInheritanceAsVirtualAfterPragma {};
+static_assert(sizeof(int SingleInheritanceAsVirtualAfterPragma::*) == 12, "");
+
+#pragma pointers_to_members(best_case)
+
+// The above holds even if the pragma comes after the definition.
+struct SingleInheritanceAsVirtualBeforePragma {};
+#pragma pointers_to_members(virtual_inheritance)
+static_assert(sizeof(int SingleInheritanceAsVirtualBeforePragma::*) == 12, "");
+
+#pragma pointers_to_members(single) // expected-error{{unexpected 'single'}}