[PATCH] Fix libstdc++-v3/include/math.h:66:1 2: error: 'constexpr bool std::isnan(double)' conflicts with a previous declaration

[John David Anglin]

The attached patch fixes a stage1 build error compiling genautomata.c on hpux.  
We need to test for obsolete
XOPEN declarations of isinf and isnan on hpux.  Further, we need to check 
individually for isinf and isnan on hpux11
since only isnan has an obsolete XOPEN declaration.

Tested on hppa2.0w-hp-hpux11.11.

Okay for trunk?

Dave
--
John David Anglin       dave.ang...@bell.net



2016-01-27  John David Anglin  <dang...@gcc.gnu.org>

        PR libstdc++/69450
        * acinclude.m4 (GLIBCXX_CHECK_MATH11_PROTO): Split check for obsolete
        isinf and isnan functions into two independent checks.  Check on hpux.
        * config.h.in: Regenerate.
        * configure: Regenerate.
        * include/c_global/cmath (isinf(double), isnan(double)): Use
        _GLIBCXX_HAVE_OBSOLETE_ISINF and _GLIBCXX_HAVE_OBSOLETE_ISNAN,
        respectively.

Index: acinclude.m4
===================================================================
--- acinclude.m4        (revision 232776)
+++ acinclude.m4        (working copy)
@@ -2186,39 +2186,54 @@
       fi
       AC_MSG_RESULT([$glibcxx_cv_math11_overload])
       ;;
-    *-*-*gnu* | *-*-aix*)
+    *-*-*gnu* | *-*-aix* | *-*-hpux*)
       # If <math.h> defines the obsolete isinf(double) and isnan(double)
       # functions (instead of or as well as the C99 generic macros) then we
       # can't define std::isinf(double) and std::isnan(double) in <cmath>
       # and must use the ones from <math.h> instead.
-      AC_MSG_CHECKING([for obsolete isinf and isnan functions in <math.h>])
-        AC_CACHE_VAL(glibcxx_cv_obsolete_isinf_isnan, [
+      AC_MSG_CHECKING([for obsolete isinf function in <math.h>])
+        AC_CACHE_VAL(glibcxx_cv_obsolete_isinf, [
           AC_COMPILE_IFELSE([AC_LANG_SOURCE(
             [#include <math.h>
              #undef isinf
-             #undef isnan
              namespace std {
                using ::isinf;
                bool isinf(float);
                bool isinf(long double);
+             }
+             using std::isinf;
+             bool b = isinf(0.0);
+          ])],
+          [glibcxx_cv_obsolete_isinf=yes],
+          [glibcxx_cv_obsolete_isinf=no]
+        )])
+      AC_MSG_RESULT([$glibcxx_cv_obsolete_isinf])
+      if test $glibcxx_cv_obsolete_isinf = yes; then
+        AC_DEFINE(HAVE_OBSOLETE_ISINF, 1,
+                  [Define if <math.h> defines obsolete isinf function.])
+      fi
+
+      AC_MSG_CHECKING([for obsolete isnan function in <math.h>])
+        AC_CACHE_VAL(glibcxx_cv_obsolete_isnan, [
+          AC_COMPILE_IFELSE([AC_LANG_SOURCE(
+            [#include <math.h>
+             #undef isnan
+             namespace std {
                using ::isnan;
                bool isnan(float);
                bool isnan(long double);
              }
-             using std::isinf;
              using std::isnan;
-             bool b = isinf(0.0) || isnan(0.0);
+             bool b = isnan(0.0);
           ])],
-          [glibcxx_cv_obsolete_isinf_isnan=yes],
-          [glibcxx_cv_obsolete_isinf_isnan=no]
+          [glibcxx_cv_obsolete_isnan=yes],
+          [glibcxx_cv_obsolete_isnan=no]
         )])
-
-
-      if test $glibcxx_cv_obsolete_isinf_isnan = yes; then
-        AC_DEFINE(HAVE_OBSOLETE_ISINF_ISNAN, 1,
-                  [Define if <math.h> defines obsolete isinf and isnan 
functions.])
+      AC_MSG_RESULT([$glibcxx_cv_obsolete_isnan])
+      if test $glibcxx_cv_obsolete_isnan = yes; then
+        AC_DEFINE(HAVE_OBSOLETE_ISNAN, 1,
+                  [Define if <math.h> defines obsolete isnan function.])
       fi
-      AC_MSG_RESULT([$glibcxx_cv_obsolete_isinf_isnan])
       ;;
   esac
 
Index: include/c_global/cmath
===================================================================
--- include/c_global/cmath      (revision 232776)
+++ include/c_global/cmath      (working copy)
@@ -610,7 +610,7 @@
   isinf(float __x)
   { return __builtin_isinf(__x); }
 
-#if _GLIBCXX_HAVE_OBSOLETE_ISINF_ISNAN \
+#if _GLIBCXX_HAVE_OBSOLETE_ISINF \
   && !_GLIBCXX_NO_OBSOLETE_ISINF_ISNAN_DYNAMIC
   using ::isinf;
 #else
@@ -635,7 +635,7 @@
   isnan(float __x)
   { return __builtin_isnan(__x); }
 
-#if _GLIBCXX_HAVE_OBSOLETE_ISINF_ISNAN \
+#if _GLIBCXX_HAVE_OBSOLETE_ISNAN \
   && !_GLIBCXX_NO_OBSOLETE_ISINF_ISNAN_DYNAMIC
   using ::isnan;
 #else