1 files changed, 34 insertions, 5 deletions

diff --git a/gl/m4/float_h.m4 b/gl/m4/float_h.m4
index 2f0c9c4e..8580c9c9 100644
--- a/gl/m4/float_h.m4
+++ b/gl/m4/float_h.m4
@@ -1,8 +1,10 @@
-# float_h.m4 serial 13
-dnl Copyright (C) 2007, 2009-2023 Free Software Foundation, Inc.
+# float_h.m4
+# serial 15
+dnl Copyright (C) 2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FLOAT_H],
 [
@@ -53,6 +55,31 @@ changequote([,])dnl
       ;;
   esac
 
+  dnl Test for completeness w.r.t. ISO C 23.
+  REPLACE_FLOAT_SNAN=0
+  AC_CACHE_CHECK([whether float.h conforms to ISO C23],
+    [gl_cv_header_float_h_isoc23],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <float.h>
+            int x[] = { FLT_DECIMAL_DIG, DBL_DECIMAL_DIG, LDBL_DECIMAL_DIG };
+            float maxf = FLT_NORM_MAX;
+            double maxd = DBL_NORM_MAX;
+            long double maxl = LDBL_NORM_MAX;
+          ]],
+          [[float sf = FLT_SNAN;
+            double sd = DBL_SNAN;
+            long double sl = LDBL_SNAN;
+            return (sf != 0) + (sd != 0) + (sl != 0);
+          ]])],
+       [gl_cv_header_float_h_isoc23=yes],
+       [gl_cv_header_float_h_isoc23=no])
+    ])
+  if test $gl_cv_header_float_h_isoc23 != yes; then
+    GL_GENERATE_FLOAT_H=true
+    REPLACE_FLOAT_SNAN=1
+  fi
+
   dnl Test against glibc-2.7 Linux/SPARC64 bug.
   REPLACE_ITOLD=0
   AC_CACHE_CHECK([whether conversion from 'int' to 'long double' works],
@@ -84,9 +111,11 @@ int main ()
                [gl_cv_func_itold_works="guessing no"],
                [gl_cv_func_itold_works="guessing yes"])
              ;;
-                   # Guess yes on native Windows.
-           mingw*) gl_cv_func_itold_works="guessing yes" ;;
-           *)      gl_cv_func_itold_works="guessing yes" ;;
+             # Guess yes on native Windows.
+           mingw* | windows*)
+             gl_cv_func_itold_works="guessing yes" ;;
+           *)
+             gl_cv_func_itold_works="guessing yes" ;;
          esac
         ])
     ])