[patch] libstdc++/64651 allow rethrow_exception to be found by ADL

[Jonathan Wakely <jwakely at redhat dot com>]

As I wrote in the PR, the standard doesn't require that
std::rethrow_exception can be found by ADL, because exception_ptr is
not necessarily defined in namespace std. This ensures it will be
found.

Tested powerpc64le-linux, committed to trunk.

commit 920a18f991d3604bf2dfdf9679411b012964f23d
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Nov 11 09:56:22 2015 +0000

    	PR libstdc++/64651
    	* libsupc++/exception_ptr.h (rethrow_exception): Add using-declaration
    	to __exception_ptr namespace.
    	* testsuite/18_support/exception_ptr/rethrow_exception.cc: Test ADL.
    	Remove unnecessary test variables.

diff --git a/libstdc++-v3/libsupc++/exception_ptr.h b/libstdc++-v3/libsupc++/exception_ptr.h
index 8fbad1c..7821c14 100644
--- a/libstdc++-v3/libsupc++/exception_ptr.h
+++ b/libstdc++-v3/libsupc++/exception_ptr.h
@@ -68,6 +68,8 @@ namespace std
 
   namespace __exception_ptr
   {
+    using std::rethrow_exception;
+
     /**
      *  @brief An opaque pointer to an arbitrary exception.
      *  @ingroup exceptions
diff --git a/libstdc++-v3/testsuite/18_support/exception_ptr/rethrow_exception.cc b/libstdc++-v3/testsuite/18_support/exception_ptr/rethrow_exception.cc
index 31da2ec..7d39892 100644
--- a/libstdc++-v3/testsuite/18_support/exception_ptr/rethrow_exception.cc
+++ b/libstdc++-v3/testsuite/18_support/exception_ptr/rethrow_exception.cc
@@ -30,7 +30,6 @@
 
 void test01()
 {
-  bool test __attribute__((unused)) = true;
   using namespace std;
 
   try {
@@ -54,7 +53,6 @@ void test02()
 
 void test03()
 {
-  bool test __attribute__((unused)) = true;
   using namespace std;
 
   exception_ptr ep;
@@ -71,7 +69,6 @@ void test03()
 
 void test04()
 {
-  bool test __attribute__((unused)) = true;
   using namespace std;
 
   // Weave the exceptions in an attempt to confuse the machinery.
@@ -103,12 +100,23 @@ void test04()
   }
 }
 
+void test05()
+{
+  // libstdc++/64651 std::rethrow_exception not found by ADL
+  // This is not required to work but is a conforming extension.
+  try {
+    rethrow_exception(std::make_exception_ptr(0));
+  } catch(...) {
+  }
+}
+
 int main()
 {
   test01();
   test02();
   test03();
   test04();
+  test05();
 
   return 0;
 }