Implement support for dependent Microsoft __if_exists/__if_not_exists

statements. As noted in the documentation for the AST node, the
semantics of __if_exists/__if_not_exists are somewhat different from
the way Visual C++ implements them, because our parsed-template
representation can't accommodate VC++ semantics without serious
contortions. Hopefully this implementation is "good enough".

llvm-svn: 142901

1 files changed, 29 insertions, 0 deletions

diff --git a/clang/test/PCH/ms-if-exists.cpp b/clang/test/PCH/ms-if-exists.cpp
new file mode 100644
index 00000000000..4bea198d9ba
--- /dev/null
+++ b/clang/test/PCH/ms-if-exists.cpp
@@ -0,0 +1,29 @@
+// RUN: %clang_cc1 -x c++ -fms-extensions -fsyntax-only -emit-pch -o %t %s
+// RUN: %clang_cc1 -x c++ -fms-extensions -fsyntax-only -include-pch %t %s -verify
+
+#ifndef HEADER
+#define HEADER
+template<typename T>
+void f(T t) {
+  __if_exists(T::foo) {
+    { }
+    t.foo();
+  }
+
+  __if_not_exists(T::bar) {
+    int *i = t; // expected-error{{no viable conversion from 'HasFoo' to 'int *'}}
+    { }
+  }
+}
+#else
+struct HasFoo { 
+  void foo();
+};
+struct HasBar { 
+  void bar(int);
+  void bar(float);
+};
+
+template void f(HasFoo); // expected-note{{in instantiation of function template specialization 'f<HasFoo>' requested here}}
+template void f(HasBar);
+#endif