re PR c++/54537 (undiagnosed using-declaration conflicting with used function)

gcc/cp/
        PR c++/54537
        * cp-tree.h: Check OVL_USED with OVERLOAD_CHECK.
        * name-lookup.c (do_nonmember_using_decl): Make sure we have an
	OVERLOAD before calling OVL_USED. Call diagnose_name_conflict
	instead of issuing an error without mentioning the conflicting
	declaration.

libstdc++-v3/
        PR c++/54537
	* include/tr1/cmath: Remove pow(double,double) overload, remove a
	duplicated comment about DR 550. Add a comment to explain the
	issue.
	* testsuite/tr1/8_c_compatibility/cmath/pow_cmath.cc: New.

gcc/testsuite/
        PR c++/54537
        * g++.dg/overload/using3.C: New.
	* g++.dg/overload/using2.C: Adjust.
	* g++.dg/lookup/using9.C: Likewise.

Co-Authored-By: Peter Bergner <bergner@vnet.ibm.com>

From-SVN: r201414

3 files changed, 53 insertions, 7 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 48cde9e..4eea924 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,11 @@
+2013-08-01  Fabien Chêne  <fabien@gcc.gnu.org>
+
+	PR c++/54537
+	* include/tr1/cmath: Remove pow(double,double) overload, remove a
+	duplicated comment about DR 550. Add a comment to explain the
+	issue.
+	* testsuite/tr1/8_c_compatibility/cmath/pow_cmath.cc: New.
+
 2013-07-31  Tim Shen  <timshen91@gmail.com>
 
 	Thompson matcher refactored. Fix grouping problem.
diff --git a/libstdc++-v3/include/tr1/cmath b/libstdc++-v3/include/tr1/cmath
index 3658afb..6e63e56 100644
--- a/libstdc++-v3/include/tr1/cmath
+++ b/libstdc++-v3/include/tr1/cmath
@@ -846,10 +846,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     nexttoward(_Tp __x, long double __y)
     { return __builtin_nexttoward(__x, __y); }
 
-  // DR 550. What should the return type of pow(float,int) be?
-  // NB: C++0x and TR1 != C++03.
-  //   using std::pow;
-
   inline float
   remainder(float __x, float __y)
   { return __builtin_remainderf(__x, __y); }
@@ -985,9 +981,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   // DR 550. What should the return type of pow(float,int) be?
   // NB: C++0x and TR1 != C++03.
-  inline double
-  pow(double __x, double __y)
-  { return std::pow(__x, __y); }
+
+  // The std::tr1::pow(double, double) overload cannot be provided
+  // here, because it would clash with ::pow(double,double) declared
+  // in <math.h>, if <tr1/math.h> is included at the same time (raised
+  // by the fix of PR c++/54537). It is not possible either to use the
+  // using-declaration 'using ::pow;' here, because if the user code
+  // has a 'using std::pow;', it would bring the pow(*,int) averloads
+  // in the tr1 namespace, which is undesirable. Consequently, the
+  // solution is to forward std::tr1::pow(double,double) to
+  // std::pow(double,double) via the templatized version below. See
+  // the discussion about this issue here:
+  // http://gcc.gnu.org/ml/gcc-patches/2012-09/msg01278.html
 
   inline float
   pow(float __x, float __y)
diff --git a/libstdc++-v3/testsuite/tr1/8_c_compatibility/cmath/pow_cmath.cc b/libstdc++-v3/testsuite/tr1/8_c_compatibility/cmath/pow_cmath.cc
new file mode 100644
index 0000000..5775450
--- /dev/null
+++ b/libstdc++-v3/testsuite/tr1/8_c_compatibility/cmath/pow_cmath.cc
@@ -0,0 +1,33 @@
+// { dg-do compile }
+
+// Copyright (C) 2013 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <cmath>
+using std::pow;
+#include <tr1/cmath>
+#include <testsuite_tr1.h>
+
+void 
+test01()
+{
+  using namespace __gnu_test;
+
+  float x = 2080703.375F;
+  check_ret_type<float>(std::pow(x, 2));
+  check_ret_type<double>(std::tr1::pow(x, 2));
+}