[libcxx] Make __wrap_iter work with gcc.

he following snippet doesn't build when using gcc and libc++:

    #include <string>
    void f(const std::string& s) { s.begin(); }
    #include <vector>
    void AppendTo(const std::vector<char>& v) { v.begin(); }

The problem is that __wrap_iter has a private constructor. It lists vector<>
and basic_string<> as friends, but gcc seems to ignore this for vector<> for
some reason. Declaring vector before the friend declaration in __wrap_iter is
enough to work around this problem, so do that. With this patch, I'm able to
build chromium/android with libc++. Without it, two translation units fail to
build. (iosfwd already provides a forward declaration of basic_string.)

As far as I can tell, this is due to a gcc bug, which I filed as
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64816.

Fixes PR22355.

http://reviews.llvm.org/D7201

llvm-svn: 227226

1 files changed, 20 insertions, 0 deletions

diff --git a/libcxx/test/std/iterators/iterators.general/gcc_workaround.pass.cpp b/libcxx/test/std/iterators/iterators.general/gcc_workaround.pass.cpp
new file mode 100644
index 00000000000..6522bd3c7bc
--- /dev/null
+++ b/libcxx/test/std/iterators/iterators.general/gcc_workaround.pass.cpp
@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// Tests workaround for  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64816.
+
+#include <string>
+
+void f(const std::string &s) { s.begin(); }
+
+#include <vector>
+
+void AppendTo(const std::vector<char> &v) { v.begin(); }
+
+int main() {}