From ac3a5bbc62949aeb061c01360632b3b8f5fafefa Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Fri, 12 May 2023 21:36:56 +0100
Subject: libstdc++: Stop using TR1 macros in <cctype> and <cfenv>

As with the two commits before this, the _GLIBCXX_USE_C99_CTYPE_TR1 and
_GLIBCXX_USE_C99_FENV_TR1 macros are misleading when they are also used
for <cctype> and <cfenv>, not only for TR1 headers. It is also wrong,
because the configure checks for TR1 use -std=c++98 and a target might
define the C99 features for C++11 but not for C++98.

Add separate configure checks for the <ctype.h> and <fenv.h> features using -std=c++11
for the checks. Use the new macros defined by those checks in the
C++11-specific parts of <cctype>, <cfenv>, and <fenv.h>.

libstdc++-v3/ChangeLog:

	* acinclude.m4 (GLIBCXX_USE_C99): Check for isblank in C++11
	mode and define _GLIBCXX_USE_C99_CTYPE. Check for <fenv.h>
	functions in C++11 mode and define _GLIBCXX_USE_C99_FENV.
	* config.h.in: Regenerate.
	* configure: Regenerate.
	* include/c_compatibility/fenv.h: Check _GLIBCXX_USE_C99_FENV
	instead of _GLIBCXX_USE_C99_FENV_TR1.
	* include/c_global/cfenv: Likewise.
	* include/c_global/cctype: Check _GLIBCXX_USE_C99_CTYPE instead
	of _GLIBCXX_USE_C99_CTYPE_TR1.
---
 libstdc++-v3/acinclude.m4 | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

(limited to 'libstdc++-v3/acinclude.m4')

diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index 0c01b52..988c532 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -1476,6 +1476,52 @@ AC_DEFUN([GLIBCXX_ENABLE_C99], [
       fi
     fi
 
+    # Check for the existence of <ctype.h> functions.
+    AC_CACHE_CHECK([for ISO C99 support for C++11 in <ctype.h>],
+    glibcxx_cv_c99_ctype, [
+    AC_TRY_COMPILE([#include <ctype.h>],
+		   [int ch;
+		    int ret;
+		    ret = isblank(ch);
+		   ],[glibcxx_cv_c99_ctype=yes],
+		     [glibcxx_cv_c99_ctype=no])
+    ])
+    if test x"$glibcxx_cv_c99_ctype" = x"yes"; then
+      AC_DEFINE(_GLIBCXX_USE_C99_CTYPE, 1,
+		[Define if C99 functions in <ctype.h> should be imported in
+		<cctype> in namespace std for C++11.])
+    fi
+
+    # Check for the existence of <fenv.h> functions.
+    AC_CHECK_HEADERS(fenv.h, ac_has_fenv_h=yes, ac_has_fenv_h=no)
+    ac_c99_fenv=no;
+    if test x"$ac_has_fenv_h" = x"yes"; then
+      AC_MSG_CHECKING([for ISO C99 support for C++11 in <fenv.h>])
+      AC_TRY_COMPILE([#include <fenv.h>],
+		     [int except, mode;
+		      fexcept_t* pflag;
+		      fenv_t* penv;
+		      int ret;
+		      ret = feclearexcept(except);
+		      ret = fegetexceptflag(pflag, except);
+		      ret = feraiseexcept(except);
+		      ret = fesetexceptflag(pflag, except);
+		      ret = fetestexcept(except);
+		      ret = fegetround();
+		      ret = fesetround(mode);
+		      ret = fegetenv(penv);
+		      ret = feholdexcept(penv);
+		      ret = fesetenv(penv);
+		      ret = feupdateenv(penv);
+		     ],[ac_c99_fenv=yes], [ac_c99_fenv=no])
+      AC_MSG_RESULT($ac_c99_fenv)
+    fi
+    if test x"$ac_c99_fenv" = x"yes"; then
+      AC_DEFINE(_GLIBCXX_USE_C99_FENV, 1,
+		[Define if C99 functions in <fenv.h> should be imported in
+		<cfenv> in namespace std for C++11.])
+    fi
+
     gcc_no_link="$ac_save_gcc_no_link"
     LIBS="$ac_save_LIBS"
     CXXFLAGS="$ac_save_CXXFLAGS"
-- 
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