Serialize the IDNS for a UsingShadowDecl rather than recomputing it.

Attempting to recompute it are doomed to fail because the IDNS of a declaration
is not necessarily preserved across serialization and deserialization (in turn
because whether a friend declaration is visible depends on whether some prior
non-friend declaration exists).

llvm-svn: 321921

1 files changed, 39 insertions, 0 deletions

diff --git a/clang/test/Modules/using-decl-friend-2.cpp b/clang/test/Modules/using-decl-friend-2.cpp
new file mode 100644
index 00000000000..0c71c37765f
--- /dev/null
+++ b/clang/test/Modules/using-decl-friend-2.cpp
@@ -0,0 +1,39 @@
+// RUN: %clang_cc1 -fmodules %s -verify
+// expected-no-diagnostics
+
+#pragma clang module build A
+module A {}
+#pragma clang module contents
+#pragma clang module begin A
+namespace N { class X; }
+#pragma clang module end
+#pragma clang module endbuild
+
+#pragma clang module build B
+module B {}
+#pragma clang module contents
+#pragma clang module begin B
+namespace N { class Friendly { friend class X; }; }
+#pragma clang module end
+#pragma clang module endbuild
+
+#pragma clang module build C
+module C {}
+#pragma clang module contents
+#pragma clang module begin C
+#pragma clang module import A
+void use_X(N::X *p);
+#pragma clang module import B
+// UsingShadowDecl names the friend declaration
+using N::X;
+#pragma clang module end
+#pragma clang module endbuild
+
+#pragma clang module import B
+namespace N { class AlsoFriendly { friend class X; }; }
+#pragma clang module import A
+#pragma clang module import C
+// The friend declaration from N::Friendly is now the first in the redecl
+// chain, so is not ordinarily visible. We need the IDNS of the UsingShadowDecl
+// to still consider it to be visible, though.
+X *p;