Use ::isinf and ::isnan if libc defines them

	PR libstdc++/48891
	* acinclude.m4 (GLIBCXX_CHECK_MATH11_PROTO): Check for obsolete isinf
	and isnan functions.
	* config.h.in: Regenerate.
	* configure: Regenerate.
	* include/c_global/cmath (isinf(double), isnan(double))
	[_GLIBCXX_HAVE_OBSOLETE_ISINF_ISNAN]: Import via using-directive.
	* testsuite/26_numerics/headers/cmath/48891.cc: New.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@232327 138bc75d-0d04-0410-961f-82ee72b054a4

6 files changed, 134 insertions, 0 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 00f7339efb8..83669c31be5 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,14 @@
+2016-01-13  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/48891
+	* acinclude.m4 (GLIBCXX_CHECK_MATH11_PROTO): Check for obsolete isinf
+	and isnan functions.
+	* config.h.in: Regenerate.
+	* configure: Regenerate.
+	* include/c_global/cmath (isinf(double), isnan(double))
+	[_GLIBCXX_HAVE_OBSOLETE_ISINF_ISNAN]: Import via using-directive.
+	* testsuite/26_numerics/headers/cmath/48891.cc: New.
+
 2016-01-13  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
 
 	PR libstdc++/66006
diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index 75e46671faf..b76e8d51b96 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -2186,6 +2186,40 @@ AC_DEFUN([GLIBCXX_CHECK_MATH11_PROTO], [
       fi
       AC_MSG_RESULT([$glibcxx_cv_math11_overload])
       ;;
+    *-*-*gnu*)
+      # If <math.h> defines the obsolete isinf(double) and isnan(double)
+      # functions (instead of or as well as the C99 generic macros) then we
+      # can't define std::isinf(double) and std::isnan(double) in <cmath>
+      # and must use the ones from <math.h> instead.
+      AC_MSG_CHECKING([for obsolete isinf and isnan functions in <math.h>])
+        AC_CACHE_VAL(glibcxx_cv_obsolete_isinf_isnan, [
+          AC_COMPILE_IFELSE([AC_LANG_SOURCE(
+            [#include <math.h>
+             #undef isinf
+             #undef isnan
+             namespace std {
+               using ::isinf;
+               bool isinf(float);
+               bool isinf(long double);
+               using ::isnan;
+               bool isnan(float);
+               bool isnan(long double);
+             }
+             using std::isinf;
+             using std::isnan;
+             bool b = isinf(0.0) || isnan(0.0);
+          ])],
+          [glibcxx_cv_obsolete_isinf_isnan=yes],
+          [glibcxx_cv_obsolete_isinf_isnan=no]
+        )])
+
+
+      if test $glibcxx_cv_obsolete_isinf_isnan = yes; then
+        AC_DEFINE(HAVE_OBSOLETE_ISINF_ISNAN, 1,
+                  [Define if <math.h> defines obsolete isinf and isnan functions.])
+      fi
+      AC_MSG_RESULT([$glibcxx_cv_obsolete_isinf_isnan])
+      ;;
   esac
 
   CXXFLAGS="$ac_save_CXXFLAGS"
diff --git a/libstdc++-v3/config.h.in b/libstdc++-v3/config.h.in
index b6cb7aa86e7..5fb0cd3dc26 100644
--- a/libstdc++-v3/config.h.in
+++ b/libstdc++-v3/config.h.in
@@ -300,6 +300,9 @@
 /* Define to 1 if you have the <nan.h> header file. */
 #undef HAVE_NAN_H
 
+/* Define if <math.h> defines obsolete isinf and isnan functions. */
+#undef HAVE_OBSOLETE_ISINF_ISNAN
+
 /* Define if poll is available in <poll.h>. */
 #undef HAVE_POLL
 
diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index 94120ec4dd5..38f14f6729e 100755
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -18174,6 +18174,54 @@ fi
       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_math11_overload" >&5
 $as_echo "$glibcxx_cv_math11_overload" >&6; }
       ;;
+    *-*-*gnu*)
+      # If <math.h> defines the obsolete isinf(double) and isnan(double)
+      # functions (instead of or as well as the C99 generic macros) then we
+      # can't define std::isinf(double) and std::isnan(double) in <cmath>
+      # and must use the ones from <math.h> instead.
+      { $as_echo "$as_me:${as_lineno-$LINENO}: checking for obsolete isinf and isnan functions in <math.h>" >&5
+$as_echo_n "checking for obsolete isinf and isnan functions in <math.h>... " >&6; }
+        if test "${glibcxx_cv_obsolete_isinf_isnan+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+
+          cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <math.h>
+             #undef isinf
+             #undef isnan
+             namespace std {
+               using ::isinf;
+               bool isinf(float);
+               bool isinf(long double);
+               using ::isnan;
+               bool isnan(float);
+               bool isnan(long double);
+             }
+             using std::isinf;
+             using std::isnan;
+             bool b = isinf(0.0) || isnan(0.0);
+
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  glibcxx_cv_obsolete_isinf_isnan=yes
+else
+  glibcxx_cv_obsolete_isinf_isnan=no
+
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+
+
+
+      if test $glibcxx_cv_obsolete_isinf_isnan = yes; then
+
+$as_echo "#define HAVE_OBSOLETE_ISINF_ISNAN 1" >>confdefs.h
+
+      fi
+      { $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_obsolete_isinf_isnan" >&5
+$as_echo "$glibcxx_cv_obsolete_isinf_isnan" >&6; }
+      ;;
   esac
 
   CXXFLAGS="$ac_save_CXXFLAGS"
diff --git a/libstdc++-v3/include/c_global/cmath b/libstdc++-v3/include/c_global/cmath
index da7ec28440b..6269e327770 100644
--- a/libstdc++-v3/include/c_global/cmath
+++ b/libstdc++-v3/include/c_global/cmath
@@ -606,9 +606,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   isinf(float __x)
   { return __builtin_isinf(__x); }
 
+#ifdef _GLIBCXX_HAVE_OBSOLETE_ISINF_ISNAN
+  using ::isinf;
+#else
   constexpr bool
   isinf(double __x)
   { return __builtin_isinf(__x); }
+#endif
 
   constexpr bool
   isinf(long double __x)
@@ -626,9 +630,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   isnan(float __x)
   { return __builtin_isnan(__x); }
 
+#ifdef _GLIBCXX_HAVE_OBSOLETE_ISINF_ISNAN
+  using ::isnan;
+#else
   constexpr bool
   isnan(double __x)
   { return __builtin_isnan(__x); }
+#endif
 
   constexpr bool
   isnan(long double __x)
diff --git a/libstdc++-v3/testsuite/26_numerics/headers/cmath/48891.cc b/libstdc++-v3/testsuite/26_numerics/headers/cmath/48891.cc
new file mode 100644
index 00000000000..ef94fe10423
--- /dev/null
+++ b/libstdc++-v3/testsuite/26_numerics/headers/cmath/48891.cc
@@ -0,0 +1,30 @@
+// Copyright (C) 2016 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/>.
+
+// { dg-options "-std=gnu++11" }
+// { dg-do compile }
+
+// PR libstdc++/48891
+
+#include <math.h>
+#include <cmath>
+
+using std::isinf;
+using std::isnan;
+
+bool d1 = isinf(1.0);
+bool d2 = isnan(1.0);