Guarantee a definition of NAN.

* lib/math.in.h (NAN): Define if missing.
* tests/test-math.c (main): Test it.
* doc/posix-headers/math.texi (math.h): Document this.
* lib/isnan.c (rpl_isnand): Use it.
* tests/test-ceilf1.c (NaN): Delete, and use NAN instead.
* tests/test-floorf1.c (NaN): Likewise.
* tests/test-frexp.c (NaN): Likewise.
* tests/test-isnand.c (NaN): Likewise.
* tests/test-isnanf.c (NaN): Likewise.
* tests/test-round1.c (NaN): Likewise.
* tests/test-roundf1.c (NaN): Likewise.
* tests/test-snprintf-posix.h (NaN): Likewise.
* tests/test-sprintf-posix.h (NaN): Likewise.
* tests/test-trunc1.c (NaN): Likewise.
* tests/test-truncf1.c (NaN): Likewise.
* tests/test-vasnprintf-posix.c (NaN): Likewise.
* tests/test-vasprintf-posix.c (NaN): Likewise.
* modules/isnand-nolibm (Depends-on): Add math.
* modules/isnanf-nolibm (Depends-on): Likewise.
* modules/isnanl (Depends-on): Likewise.
* modules/isnanl-nolibm (Depends-on): Likewise.
* modules/snprintf-posix-tests (Depends-on): Likewise.
* modules/sprintf-posix-tests (Depends-on): Likewise.
* modules/vsnprintf-posix-tests (Depends-on): Likewise.
* modules/vsprintf-posix-tests (Depends-on): Likewise.
* modules/vasnprintf-posix-tests (Depends-on): Likewise.
* modules/vasprintf-posix-tests (Depends-on): Likewise.

Signed-off-by: Eric Blake <ebb9@byu.net>

28 files changed, 139 insertions, 216 deletions

diff --git a/ChangeLog b/ChangeLog
index 2202e8eb79..c02f097613 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,34 @@
+2008-03-31  Eric Blake  <ebb9@byu.net>
+
+	Guarantee a definition of NAN.
+	* lib/math.in.h (NAN): Define if missing.
+	* tests/test-math.c (main): Test it.
+	* doc/posix-headers/math.texi (math.h): Document this.
+	* lib/isnan.c (rpl_isnand): Use it.
+	* tests/test-ceilf1.c (NaN): Delete, and use NAN instead.
+	* tests/test-floorf1.c (NaN): Likewise.
+	* tests/test-frexp.c (NaN): Likewise.
+	* tests/test-isnand.c (NaN): Likewise.
+	* tests/test-isnanf.c (NaN): Likewise.
+	* tests/test-round1.c (NaN): Likewise.
+	* tests/test-roundf1.c (NaN): Likewise.
+	* tests/test-snprintf-posix.h (NaN): Likewise.
+	* tests/test-sprintf-posix.h (NaN): Likewise.
+	* tests/test-trunc1.c (NaN): Likewise.
+	* tests/test-truncf1.c (NaN): Likewise.
+	* tests/test-vasnprintf-posix.c (NaN): Likewise.
+	* tests/test-vasprintf-posix.c (NaN): Likewise.
+	* modules/isnand-nolibm (Depends-on): Add math.
+	* modules/isnanf-nolibm (Depends-on): Likewise.
+	* modules/isnanl (Depends-on): Likewise.
+	* modules/isnanl-nolibm (Depends-on): Likewise.
+	* modules/snprintf-posix-tests (Depends-on): Likewise.
+	* modules/sprintf-posix-tests (Depends-on): Likewise.
+	* modules/vsnprintf-posix-tests (Depends-on): Likewise.
+	* modules/vsprintf-posix-tests (Depends-on): Likewise.
+	* modules/vasnprintf-posix-tests (Depends-on): Likewise.
+	* modules/vasprintf-posix-tests (Depends-on): Likewise.
+
 2008-03-31  Bruno Haible  <bruno@clisp.org>
 
 	* tests/test-strtod.c (main): Update results for OSF/1 platforms.
diff --git a/doc/posix-headers/math.texi b/doc/posix-headers/math.texi
index dde9cd0378..a207e16a41 100644
--- a/doc/posix-headers/math.texi
+++ b/doc/posix-headers/math.texi
@@ -7,8 +7,14 @@ Gnulib module: math
 
 Portability problems fixed by Gnulib:
 @itemize
+@item
+Some platforms do not provide a definition of NAN:
+Solaris 8.
+
 @end itemize
 
 Portability problems not fixed by Gnulib:
 @itemize
+NAN is not a compile time constant with some broken compilers:
+Compaq (ex-DEC) C 6.4
 @end itemize
diff --git a/lib/isnan.c b/lib/isnan.c
index a5ca38df41..81f394d165 100644
--- a/lib/isnan.c
+++ b/lib/isnan.c
@@ -19,6 +19,7 @@
 #include <config.h>
 
 #include <float.h>
+#include <math.h>
 #include <string.h>
 
 #include "float+.h"
@@ -111,11 +112,10 @@ FUNC (DOUBLE x)
      also fails when constant-folding 0.0 / 0.0 even when constant-folding is
      not required.  The SGI MIPSpro C compiler complains about "floating-point
      operation result is out of range".  */
-  static DOUBLE zero = L_(0.0);
   memory_double nan;
   DOUBLE plus_inf = L_(1.0) / L_(0.0);
   DOUBLE minus_inf = -L_(1.0) / L_(0.0);
-  nan.value = zero / zero;
+  nan.value = NAN;
 #  else
   static memory_double nan = { L_(0.0) / L_(0.0) };
   static DOUBLE plus_inf = L_(1.0) / L_(0.0);
diff --git a/lib/math.in.h b/lib/math.in.h
index c3515d7349..bb715aeeaf 100644
--- a/lib/math.in.h
+++ b/lib/math.in.h
@@ -1,6 +1,6 @@
 /* A GNU-like <math.h>.
 
-   Copyright (C) 2002-2003, 2007 Free Software Foundation, Inc.
+   Copyright (C) 2002-2003, 2007, 2008 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -32,6 +32,24 @@ extern "C" {
 #endif
 
 
+/* POSIX allows platforms that don't support NAN.  But all major
+   machines in the past 15 years have supported something close to
+   IEEE NaN, so we define this unconditionally.  */
+#ifndef NAN
+  /* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0.  */
+# ifdef __DECC
+static float
+_NaN ()
+{
+  static float zero = 0.0f;
+  return zero / zero;
+}
+#  define NAN (_NaN())
+# else
+#  define NAN (0.0f / 0.0f)
+# endif
+#endif
+
 /* Write x as
      x = mantissa * 2^exp
    where
diff --git a/modules/isnand-nolibm b/modules/isnand-nolibm
index 6bb8c7da33..cab173d5c7 100644
--- a/modules/isnand-nolibm
+++ b/modules/isnand-nolibm
@@ -10,6 +10,7 @@ m4/isnand.m4
 
 Depends-on:
 fpieee
+math
 
 configure.ac:
 gl_FUNC_ISNAND_NO_LIBM
diff --git a/modules/isnanf-nolibm b/modules/isnanf-nolibm
index 3f906295fa..1489e307b5 100644
--- a/modules/isnanf-nolibm
+++ b/modules/isnanf-nolibm
@@ -10,6 +10,7 @@ m4/isnanf.m4
 
 Depends-on:
 fpieee
+math
 
 configure.ac:
 gl_FUNC_ISNANF_NO_LIBM
diff --git a/modules/isnanl b/modules/isnanl
index 026981f274..6ba1ee4cb8 100644
--- a/modules/isnanl
+++ b/modules/isnanl
@@ -11,6 +11,7 @@ m4/isnanl.m4
 Depends-on:
 float
 fpieee
+math
 
 configure.ac:
 gl_FUNC_ISNANL
diff --git a/modules/isnanl-nolibm b/modules/isnanl-nolibm
index 9250fef0ea..783dc770dc 100644
--- a/modules/isnanl-nolibm
+++ b/modules/isnanl-nolibm
@@ -11,6 +11,7 @@ m4/isnanl.m4
 Depends-on:
 float
 fpieee
+math
 
 configure.ac:
 gl_FUNC_ISNANL_NO_LIBM
diff --git a/modules/snprintf-posix-tests b/modules/snprintf-posix-tests
index 72303bdc10..3826051248 100644
--- a/modules/snprintf-posix-tests
+++ b/modules/snprintf-posix-tests
@@ -4,6 +4,7 @@ tests/test-snprintf-posix.h
 tests/test-snprintf.c
 
 Depends-on:
+math
 stdint
 
 configure.ac:
diff --git a/modules/sprintf-posix-tests b/modules/sprintf-posix-tests
index 69673d4983..5df186ad87 100644
--- a/modules/sprintf-posix-tests
+++ b/modules/sprintf-posix-tests
@@ -3,6 +3,7 @@ tests/test-sprintf-posix.c
 tests/test-sprintf-posix.h
 
 Depends-on:
+math
 stdint
 
 configure.ac:
diff --git a/modules/vasnprintf-posix-tests b/modules/vasnprintf-posix-tests
index 65c1351d00..d8a39d4d91 100644
--- a/modules/vasnprintf-posix-tests
+++ b/modules/vasnprintf-posix-tests
@@ -5,6 +5,7 @@ tests/test-vasnprintf-posix2.c
 m4/locale-fr.m4
 
 Depends-on:
+math
 stdint
 
 configure.ac:
diff --git a/modules/vasprintf-posix-tests b/modules/vasprintf-posix-tests
index 485e513b75..391c6a135e 100644
--- a/modules/vasprintf-posix-tests
+++ b/modules/vasprintf-posix-tests
@@ -2,6 +2,7 @@ Files:
 tests/test-vasprintf-posix.c
 
 Depends-on:
+math
 stdint
 
 configure.ac:
diff --git a/modules/vsnprintf-posix-tests b/modules/vsnprintf-posix-tests
index f60a7b6a1f..1604b1e3b9 100644
--- a/modules/vsnprintf-posix-tests
+++ b/modules/vsnprintf-posix-tests
@@ -4,6 +4,7 @@ tests/test-snprintf-posix.h
 tests/test-vsnprintf.c
 
 Depends-on:
+math
 stdint
 
 configure.ac:
diff --git a/modules/vsprintf-posix-tests b/modules/vsprintf-posix-tests
index 37be4fce32..7c42039315 100644
--- a/modules/vsprintf-posix-tests
+++ b/modules/vsprintf-posix-tests
@@ -3,6 +3,7 @@ tests/test-vsprintf-posix.c
 tests/test-sprintf-posix.h
 
 Depends-on:
+math
 stdint
 
 configure.ac:
diff --git a/tests/test-ceilf1.c b/tests/test-ceilf1.c
index 36a116358f..b323227b74 100644
--- a/tests/test-ceilf1.c
+++ b/tests/test-ceilf1.c
@@ -1,5 +1,5 @@
 /* Test of rounding towards positive infinity.
-   Copyright (C) 2007 Free Software Foundation, Inc.
+   Copyright (C) 2007, 2008 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -36,18 +36,6 @@
     }									     \
   while (0)
 
-/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0.  */
-#ifdef __DECC
-static float
-NaN ()
-{
-  static float zero = 0.0f;
-  return zero / zero;
-}
-#else
-# define NaN() (0.0f / 0.0f)
-#endif
-
 int
 main ()
 {
@@ -79,7 +67,7 @@ main ()
   ASSERT (ceilf (1.0f / 0.0f) == 1.0f / 0.0f);
   ASSERT (ceilf (-1.0f / 0.0f) == -1.0f / 0.0f);
   /* NaNs.  */
-  ASSERT (isnanf (ceilf (NaN ())));
+  ASSERT (isnanf (ceilf (NAN)));
 
   return 0;
 }
diff --git a/tests/test-floorf1.c b/tests/test-floorf1.c
index afd006b085..a45bcfc2ac 100644
--- a/tests/test-floorf1.c
+++ b/tests/test-floorf1.c
@@ -1,5 +1,5 @@
 /* Test of rounding towards negative infinity.
-   Copyright (C) 2007 Free Software Foundation, Inc.
+   Copyright (C) 2007, 2008 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -36,18 +36,6 @@
     }									     \
   while (0)
 
-/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0.  */
-#ifdef __DECC
-static float
-NaN ()
-{
-  static float zero = 0.0f;
-  return zero / zero;
-}
-#else
-# define NaN() (0.0f / 0.0f)
-#endif
-
 int
 main ()
 {
@@ -79,7 +67,7 @@ main ()
   ASSERT (floorf (1.0f / 0.0f) == 1.0f / 0.0f);
   ASSERT (floorf (-1.0f / 0.0f) == -1.0f / 0.0f);
   /* NaNs.  */
-  ASSERT (isnanf (floorf (NaN ())));
+  ASSERT (isnanf (floorf (NAN)));
 
   return 0;
 }
diff --git a/tests/test-frexp.c b/tests/test-frexp.c
index 47db2bec45..cb80f56413 100644
--- a/tests/test-frexp.c
+++ b/tests/test-frexp.c
@@ -37,18 +37,6 @@
     }									     \
   while (0)
 
-/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0.  */
-#ifdef __DECC
-static double
-NaN ()
-{
-  static double zero = 0.0;
-  return zero / zero;
-}
-#else
-# define NaN() (0.0 / 0.0)
-#endif
-
 static double
 my_ldexp (double x, int d)
 {
@@ -73,7 +61,7 @@ main ()
   { /* NaN.  */
     int exp = -9999;
     double mantissa;
-    x = NaN ();
+    x = NAN;
     mantissa = frexp (x, &exp);
     ASSERT (isnand (mantissa));
   }
diff --git a/tests/test-isnand.c b/tests/test-isnand.c
index 0bc0a26dee..1dc923896d 100644
--- a/tests/test-isnand.c
+++ b/tests/test-isnand.c
@@ -21,6 +21,7 @@
 #include "isnand.h"
 
 #include <limits.h>
+#include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -35,18 +36,6 @@
     }									     \
   while (0)
 
-/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0.  */
-#ifdef __DECC
-static double
-NaN ()
-{
-  static double zero = 0.0;
-  return zero / zero;
-}
-#else
-# define NaN() (0.0 / 0.0)
-#endif
-
 int
 main ()
 {
@@ -63,7 +52,7 @@ main ()
   ASSERT (!isnand (1.0 / 0.0));
   ASSERT (!isnand (-1.0 / 0.0));
   /* Quiet NaN.  */
-  ASSERT (isnand (NaN ()));
+  ASSERT (isnand (NAN));
 #if defined DBL_EXPBIT0_WORD && defined DBL_EXPBIT0_BIT
   /* Signalling NaN.  */
   {
@@ -71,7 +60,7 @@ main ()
       ((sizeof (double) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
     typedef union { double value; unsigned int word[NWORDS]; } memory_double;
     memory_double m;
-    m.value = NaN ();
+    m.value = NAN;
 # if DBL_EXPBIT0_BIT > 0
     m.word[DBL_EXPBIT0_WORD] ^= (unsigned int) 1 << (DBL_EXPBIT0_BIT - 1);
 # else
diff --git a/tests/test-isnanf.c b/tests/test-isnanf.c
index c433089900..6c084acb2e 100644
--- a/tests/test-isnanf.c
+++ b/tests/test-isnanf.c
@@ -1,5 +1,5 @@
 /* Test of isnanf() substitute.
-   Copyright (C) 2007 Free Software Foundation, Inc.
+   Copyright (C) 2007, 2008 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -21,6 +21,7 @@
 #include "isnanf.h"
 
 #include <limits.h>
+#include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -35,18 +36,6 @@
     }									     \
   while (0)
 
-/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0.  */
-#ifdef __DECC
-static float
-NaN ()
-{
-  static float zero = 0.0f;
-  return zero / zero;
-}
-#else
-# define NaN() (0.0f / 0.0f)
-#endif
-
 int
 main ()
 {
@@ -63,7 +52,7 @@ main ()
   ASSERT (!isnanf (1.0f / 0.0f));
   ASSERT (!isnanf (-1.0f / 0.0f));
   /* Quiet NaN.  */
-  ASSERT (isnanf (NaN ()));
+  ASSERT (isnanf (NAN));
 #if defined FLT_EXPBIT0_WORD && defined FLT_EXPBIT0_BIT
   /* Signalling NaN.  */
   {
@@ -71,7 +60,7 @@ main ()
       ((sizeof (float) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
     typedef union { float value; unsigned int word[NWORDS]; } memory_float;
     memory_float m;
-    m.value = NaN ();
+    m.value = NAN;
 # if FLT_EXPBIT0_BIT > 0
     m.word[FLT_EXPBIT0_WORD] ^= (unsigned int) 1 << (FLT_EXPBIT0_BIT - 1);
 # else
diff --git a/tests/test-math.c b/tests/test-math.c
index 893ca81593..5c00581d17 100644
--- a/tests/test-math.c
+++ b/tests/test-math.c
@@ -1,5 +1,5 @@
 /* Test of <math.h> substitute.
-   Copyright (C) 2007 Free Software Foundation, Inc.
+   Copyright (C) 2007, 2008 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -20,8 +20,14 @@
 
 #include <math.h>
 
+#ifndef NAN
+# error NAN should be defined
+choke me
+#endif
+
 int
 main ()
 {
-  return 0;
+  double d = NAN;
+  return d == d;
 }
diff --git a/tests/test-round1.c b/tests/test-round1.c
index 625b9ff366..704e1da640 100644
--- a/tests/test-round1.c
+++ b/tests/test-round1.c
@@ -3,7 +3,7 @@
 
    This program 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 2, or (at your option)
+   the Free Software Foundation; either version 3, or (at your option)
    any later version.
 
    This program is distributed in the hope that it will be useful,
@@ -38,18 +38,6 @@
     }									     \
   while (0)
 
-/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0.  */
-#ifdef __DECC
-static double
-NaN ()
-{
-  static double zero = 0.0;
-  return zero / zero;
-}
-#else
-# define NaN() (0.0 / 0.0)
-#endif
-
 int
 main ()
 {
@@ -86,7 +74,7 @@ main ()
   ASSERT (round (1.0 / 0.0) == 1.0 / 0.0);
   ASSERT (round (-1.0 / 0.0) == -1.0 / 0.0);
   /* NaNs.  */
-  ASSERT (isnand (round (NaN ())));
+  ASSERT (isnand (round (NAN)));
 
   return 0;
 }
diff --git a/tests/test-roundf1.c b/tests/test-roundf1.c
index 67d5c7fe90..aeee3b1739 100644
--- a/tests/test-roundf1.c
+++ b/tests/test-roundf1.c
@@ -1,9 +1,9 @@
 /* Test of rounding to nearest, breaking ties away from zero.
-   Copyright (C) 2007 Free Software Foundation, Inc.
+   Copyright (C) 2007, 2008 Free Software Foundation, Inc.
 
    This program 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 2, or (at your option)
+   the Free Software Foundation; either version 3, or (at your option)
    any later version.
 
    This program is distributed in the hope that it will be useful,
@@ -38,18 +38,6 @@
     }									     \
   while (0)
 
-/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0.  */
-#ifdef __DECC
-static float
-NaN ()
-{
-  static float zero = 0.0f;
-  return zero / zero;
-}
-#else
-# define NaN() (0.0f / 0.0f)
-#endif
-
 int
 main ()
 {
@@ -86,7 +74,7 @@ main ()
   ASSERT (roundf (1.0 / 0.0f) == 1.0 / 0.0f);
   ASSERT (roundf (-1.0 / 0.0f) == -1.0 / 0.0f);
   /* NaNs.  */
-  ASSERT (isnanf (roundf (NaN ())));
+  ASSERT (isnanf (roundf (NAN)));
 
   return 0;
 }
diff --git a/tests/test-snprintf-posix.h b/tests/test-snprintf-posix.h
index 94f5e671c4..4d69267a62 100644
--- a/tests/test-snprintf-posix.h
+++ b/tests/test-snprintf-posix.h
@@ -16,17 +16,7 @@
 
 /* Written by Bruno Haible <bruno@clisp.org>, 2007.  */
 
-/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0.  */
-#ifdef __DECC
-static double
-NaN ()
-{
-  static double zero = 0.0;
-  return zero / zero;
-}
-#else
-# define NaN() (0.0 / 0.0)
-#endif
+#include <math.h>
 
 /* The SGI MIPS floating-point format does not distinguish 0.0 and -0.0.  */
 static int
@@ -81,7 +71,7 @@ strisnan (const char *string, size_t start_index, size_t end_index, int uppercas
     }
   return 0;
 }
-	  
+
 static void
 test_function (int (*my_snprintf) (char *, size_t, const char *, ...))
 {
@@ -207,7 +197,7 @@ test_function (int (*my_snprintf) (char *, size_t, const char *, ...))
   { /* NaN.  */
     char result[100];
     int retval =
-      my_snprintf (result, sizeof (result), "%a %d", NaN (), 33, 44, 55);
+      my_snprintf (result, sizeof (result), "%a %d", NAN, 33, 44, 55);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 0)
 	    && strcmp (result + strlen (result) - 3, " 33") == 0);
@@ -404,7 +394,7 @@ test_function (int (*my_snprintf) (char *, size_t, const char *, ...))
   { /* FLAG_ZERO with NaN.  */
     char result[100];
     int retval =
-      my_snprintf (result, sizeof (result), "%050a %d", NaN (), 33, 44, 55);
+      my_snprintf (result, sizeof (result), "%050a %d", NAN, 33, 44, 55);
     /* "0000000nan 33" is not a valid result; see
        <http://lists.gnu.org/archive/html/bug-gnulib/2007-04/msg00107.html> */
     ASSERT (strlen (result) == 50 + 3
@@ -918,7 +908,7 @@ test_function (int (*my_snprintf) (char *, size_t, const char *, ...))
   { /* NaN.  */
     char result[100];
     int retval =
-      my_snprintf (result, sizeof (result), "%f %d", NaN (), 33, 44, 55);
+      my_snprintf (result, sizeof (result), "%f %d", NAN, 33, 44, 55);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 0)
 	    && strcmp (result + strlen (result) - 3, " 33") == 0);
@@ -999,7 +989,7 @@ test_function (int (*my_snprintf) (char *, size_t, const char *, ...))
   { /* FLAG_ZERO with NaN.  */
     char result[100];
     int retval =
-      my_snprintf (result, sizeof (result), "%050f %d", NaN (), 33, 44, 55);
+      my_snprintf (result, sizeof (result), "%050f %d", NAN, 33, 44, 55);
     ASSERT (strlen (result) == 50 + 3
 	    && strisnan (result, strspn (result, " "), strlen (result) - 3, 0)
 	    && strcmp (result + strlen (result) - 3, " 33") == 0);
@@ -1414,7 +1404,7 @@ test_function (int (*my_snprintf) (char *, size_t, const char *, ...))
   { /* NaN.  */
     char result[100];
     int retval =
-      my_snprintf (result, sizeof (result), "%F %d", NaN (), 33, 44, 55);
+      my_snprintf (result, sizeof (result), "%F %d", NAN, 33, 44, 55);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 1)
 	    && strcmp (result + strlen (result) - 3, " 33") == 0);
@@ -1708,7 +1698,7 @@ test_function (int (*my_snprintf) (char *, size_t, const char *, ...))
   { /* NaN.  */
     char result[100];
     int retval =
-      my_snprintf (result, sizeof (result), "%e %d", NaN (), 33, 44, 55);
+      my_snprintf (result, sizeof (result), "%e %d", NAN, 33, 44, 55);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 0)
 	    && strcmp (result + strlen (result) - 3, " 33") == 0);
@@ -1799,7 +1789,7 @@ test_function (int (*my_snprintf) (char *, size_t, const char *, ...))
   { /* FLAG_ZERO with NaN.  */
     char result[100];
     int retval =
-      my_snprintf (result, sizeof (result), "%050e %d", NaN (), 33, 44, 55);
+      my_snprintf (result, sizeof (result), "%050e %d", NAN, 33, 44, 55);
     ASSERT (strlen (result) == 50 + 3
 	    && strisnan (result, strspn (result, " "), strlen (result) - 3, 0)
 	    && strcmp (result + strlen (result) - 3, " 33") == 0);
@@ -2316,7 +2306,7 @@ test_function (int (*my_snprintf) (char *, size_t, const char *, ...))
   { /* NaN.  */
     char result[100];
     int retval =
-      my_snprintf (result, sizeof (result), "%g %d", NaN (), 33, 44, 55);
+      my_snprintf (result, sizeof (result), "%g %d", NAN, 33, 44, 55);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 0)
 	    && strcmp (result + strlen (result) - 3, " 33") == 0);
@@ -2400,7 +2390,7 @@ test_function (int (*my_snprintf) (char *, size_t, const char *, ...))
   { /* FLAG_ZERO with NaN.  */
     char result[100];
     int retval =
-      my_snprintf (result, sizeof (result), "%050g %d", NaN (), 33, 44, 55);
+      my_snprintf (result, sizeof (result), "%050g %d", NAN, 33, 44, 55);
     ASSERT (strlen (result) == 50 + 3
 	    && strisnan (result, strspn (result, " "), strlen (result) - 3, 0)
 	    && strcmp (result + strlen (result) - 3, " 33") == 0);
diff --git a/tests/test-sprintf-posix.h b/tests/test-sprintf-posix.h
index 35e9d47bcc..ac2afcf91b 100644
--- a/tests/test-sprintf-posix.h
+++ b/tests/test-sprintf-posix.h
@@ -16,17 +16,7 @@
 
 /* Written by Bruno Haible <bruno@clisp.org>, 2007.  */
 
-/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0.  */
-#ifdef __DECC
-static double
-NaN ()
-{
-  static double zero = 0.0;
-  return zero / zero;
-}
-#else
-# define NaN() (0.0 / 0.0)
-#endif
+#include <math.h>
 
 /* The SGI MIPS floating-point format does not distinguish 0.0 and -0.0.  */
 static int
@@ -193,7 +183,7 @@ test_function (int (*my_sprintf) (char *, const char *, ...))
   { /* NaN.  */
     char result[1000];
     int retval =
-      my_sprintf (result, "%a %d", NaN (), 33, 44, 55);
+      my_sprintf (result, "%a %d", NAN, 33, 44, 55);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 0)
 	    && strcmp (result + strlen (result) - 3, " 33") == 0);
@@ -390,7 +380,7 @@ test_function (int (*my_sprintf) (char *, const char *, ...))
   { /* FLAG_ZERO with NaN.  */
     char result[1000];
     int retval =
-      my_sprintf (result, "%050a %d", NaN (), 33, 44, 55);
+      my_sprintf (result, "%050a %d", NAN, 33, 44, 55);
     /* "0000000nan 33" is not a valid result; see
        <http://lists.gnu.org/archive/html/bug-gnulib/2007-04/msg00107.html> */
     ASSERT (strlen (result) == 50 + 3
@@ -904,7 +894,7 @@ test_function (int (*my_sprintf) (char *, const char *, ...))
   { /* NaN.  */
     char result[1000];
     int retval =
-      my_sprintf (result, "%f %d", NaN (), 33, 44, 55);
+      my_sprintf (result, "%f %d", NAN, 33, 44, 55);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 0)
 	    && strcmp (result + strlen (result) - 3, " 33") == 0);
@@ -979,7 +969,7 @@ test_function (int (*my_sprintf) (char *, const char *, ...))
   { /* FLAG_ZERO with NaN.  */
     char result[1000];
     int retval =
-      my_sprintf (result, "%050f %d", NaN (), 33, 44, 55);
+      my_sprintf (result, "%050f %d", NAN, 33, 44, 55);
     ASSERT (strlen (result) == 50 + 3
 	    && strisnan (result, strspn (result, " "), strlen (result) - 3, 0)
 	    && strcmp (result + strlen (result) - 3, " 33") == 0);
@@ -1388,7 +1378,7 @@ test_function (int (*my_sprintf) (char *, const char *, ...))
   { /* NaN.  */
     char result[1000];
     int retval =
-      my_sprintf (result, "%F %d", NaN (), 33, 44, 55);
+      my_sprintf (result, "%F %d", NAN, 33, 44, 55);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 1)
 	    && strcmp (result + strlen (result) - 3, " 33") == 0);
@@ -1682,7 +1672,7 @@ test_function (int (*my_sprintf) (char *, const char *, ...))
   { /* NaN.  */
     char result[1000];
     int retval =
-      my_sprintf (result, "%e %d", NaN (), 33, 44, 55);
+      my_sprintf (result, "%e %d", NAN, 33, 44, 55);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 0)
 	    && strcmp (result + strlen (result) - 3, " 33") == 0);
@@ -1773,7 +1763,7 @@ test_function (int (*my_sprintf) (char *, const char *, ...))
   { /* FLAG_ZERO with NaN.  */
     char result[1000];
     int retval =
-      my_sprintf (result, "%050e %d", NaN (), 33, 44, 55);
+      my_sprintf (result, "%050e %d", NAN, 33, 44, 55);
     ASSERT (strlen (result) == 50 + 3
 	    && strisnan (result, strspn (result, " "), strlen (result) - 3, 0)
 	    && strcmp (result + strlen (result) - 3, " 33") == 0);
@@ -2290,7 +2280,7 @@ test_function (int (*my_sprintf) (char *, const char *, ...))
   { /* NaN.  */
     char result[1000];
     int retval =
-      my_sprintf (result, "%g %d", NaN (), 33, 44, 55);
+      my_sprintf (result, "%g %d", NAN, 33, 44, 55);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 0)
 	    && strcmp (result + strlen (result) - 3, " 33") == 0);
@@ -2374,7 +2364,7 @@ test_function (int (*my_sprintf) (char *, const char *, ...))
   { /* FLAG_ZERO with NaN.  */
     char result[1000];
     int retval =
-      my_sprintf (result, "%050g %d", NaN (), 33, 44, 55);
+      my_sprintf (result, "%050g %d", NAN, 33, 44, 55);
     ASSERT (strlen (result) == 50 + 3
 	    && strisnan (result, strspn (result, " "), strlen (result) - 3, 0)
 	    && strcmp (result + strlen (result) - 3, " 33") == 0);
diff --git a/tests/test-trunc1.c b/tests/test-trunc1.c
index a2d6dd4b4a..6b283636e4 100644
--- a/tests/test-trunc1.c
+++ b/tests/test-trunc1.c
@@ -36,18 +36,6 @@
     }									     \
   while (0)
 
-/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0.  */
-#ifdef __DECC
-static double
-NaN ()
-{
-  static double zero = 0.0;
-  return zero / zero;
-}
-#else
-# define NaN() (0.0 / 0.0)
-#endif
-
 int
 main ()
 {
@@ -78,7 +66,7 @@ main ()
   ASSERT (trunc (1.0 / 0.0) == 1.0 / 0.0);
   ASSERT (trunc (-1.0 / 0.0) == -1.0 / 0.0);
   /* NaNs.  */
-  ASSERT (isnand (trunc (NaN ())));
+  ASSERT (isnand (trunc (NAN)));
 
   return 0;
 }
diff --git a/tests/test-truncf1.c b/tests/test-truncf1.c
index 8915f9faeb..9d365763fa 100644
--- a/tests/test-truncf1.c
+++ b/tests/test-truncf1.c
@@ -1,5 +1,5 @@
 /* Test of rounding towards zero.
-   Copyright (C) 2007 Free Software Foundation, Inc.
+   Copyright (C) 2007, 2008 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -36,18 +36,6 @@
     }									     \
   while (0)
 
-/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0.  */
-#ifdef __DECC
-static float
-NaN ()
-{
-  static float zero = 0.0f;
-  return zero / zero;
-}
-#else
-# define NaN() (0.0f / 0.0f)
-#endif
-
 int
 main ()
 {
@@ -78,7 +66,7 @@ main ()
   ASSERT (truncf (1.0f / 0.0f) == 1.0f / 0.0f);
   ASSERT (truncf (-1.0f / 0.0f) == -1.0f / 0.0f);
   /* NaNs.  */
-  ASSERT (isnanf (truncf (NaN ())));
+  ASSERT (isnanf (truncf (NAN)));
 
   return 0;
 }
diff --git a/tests/test-vasnprintf-posix.c b/tests/test-vasnprintf-posix.c
index e947cc79fb..c29546a857 100644
--- a/tests/test-vasnprintf-posix.c
+++ b/tests/test-vasnprintf-posix.c
@@ -21,6 +21,7 @@
 #include "vasnprintf.h"
 
 #include <float.h>
+#include <math.h>
 #include <stdarg.h>
 #include <stddef.h>
 #include <stdio.h>
@@ -40,18 +41,6 @@
     }									     \
   while (0)
 
-/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0.  */
-#ifdef __DECC
-static double
-NaN ()
-{
-  static double zero = 0.0;
-  return zero / zero;
-}
-#else
-# define NaN() (0.0 / 0.0)
-#endif
-
 /* The SGI MIPS floating-point format does not distinguish 0.0 and -0.0.  */
 static int
 have_minus_zero ()
@@ -105,7 +94,7 @@ strisnan (const char *string, size_t start_index, size_t end_index, int uppercas
     }
   return 0;
 }
-	  
+
 static void
 test_function (char * (*my_asnprintf) (char *, size_t *, const char *, ...))
 {
@@ -257,7 +246,7 @@ test_function (char * (*my_asnprintf) (char *, size_t *, const char *, ...))
   { /* NaN.  */
     size_t length;
     char *result =
-      my_asnprintf (NULL, &length, "%a %d", NaN (), 33, 44, 55);
+      my_asnprintf (NULL, &length, "%a %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 0)
@@ -490,7 +479,7 @@ test_function (char * (*my_asnprintf) (char *, size_t *, const char *, ...))
   { /* FLAG_ZERO with NaN.  */
     size_t length;
     char *result =
-      my_asnprintf (NULL, &length, "%050a %d", NaN (), 33, 44, 55);
+      my_asnprintf (NULL, &length, "%050a %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     /* "0000000nan 33" is not a valid result; see
        <http://lists.gnu.org/archive/html/bug-gnulib/2007-04/msg00107.html> */
@@ -1086,7 +1075,7 @@ test_function (char * (*my_asnprintf) (char *, size_t *, const char *, ...))
   { /* NaN.  */
     size_t length;
     char *result =
-      my_asnprintf (NULL, &length, "%f %d", NaN (), 33, 44, 55);
+      my_asnprintf (NULL, &length, "%f %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 0)
@@ -1179,7 +1168,7 @@ test_function (char * (*my_asnprintf) (char *, size_t *, const char *, ...))
   { /* FLAG_ZERO with NaN.  */
     size_t length;
     char *result =
-      my_asnprintf (NULL, &length, "%050f %d", NaN (), 33, 44, 55);
+      my_asnprintf (NULL, &length, "%050f %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     ASSERT (strlen (result) == 50 + 3
 	    && strisnan (result, strspn (result, " "), strlen (result) - 3, 0)
@@ -1658,7 +1647,7 @@ test_function (char * (*my_asnprintf) (char *, size_t *, const char *, ...))
   { /* NaN.  */
     size_t length;
     char *result =
-      my_asnprintf (NULL, &length, "%F %d", NaN (), 33, 44, 55);
+      my_asnprintf (NULL, &length, "%F %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 1)
@@ -1997,7 +1986,7 @@ test_function (char * (*my_asnprintf) (char *, size_t *, const char *, ...))
   { /* NaN.  */
     size_t length;
     char *result =
-      my_asnprintf (NULL, &length, "%e %d", NaN (), 33, 44, 55);
+      my_asnprintf (NULL, &length, "%e %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 0)
@@ -2108,7 +2097,7 @@ test_function (char * (*my_asnprintf) (char *, size_t *, const char *, ...))
   { /* FLAG_ZERO with NaN.  */
     size_t length;
     char *result =
-      my_asnprintf (NULL, &length, "%050e %d", NaN (), 33, 44, 55);
+      my_asnprintf (NULL, &length, "%050e %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     ASSERT (strlen (result) == 50 + 3
 	    && strisnan (result, strspn (result, " "), strlen (result) - 3, 0)
@@ -2699,7 +2688,7 @@ test_function (char * (*my_asnprintf) (char *, size_t *, const char *, ...))
   { /* NaN.  */
     size_t length;
     char *result =
-      my_asnprintf (NULL, &length, "%g %d", NaN (), 33, 44, 55);
+      my_asnprintf (NULL, &length, "%g %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 0)
@@ -2803,7 +2792,7 @@ test_function (char * (*my_asnprintf) (char *, size_t *, const char *, ...))
   { /* FLAG_ZERO with NaN.  */
     size_t length;
     char *result =
-      my_asnprintf (NULL, &length, "%050g %d", NaN (), 33, 44, 55);
+      my_asnprintf (NULL, &length, "%050g %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     ASSERT (strlen (result) == 50 + 3
 	    && strisnan (result, strspn (result, " "), strlen (result) - 3, 0)
diff --git a/tests/test-vasprintf-posix.c b/tests/test-vasprintf-posix.c
index 68da28c817..806ce749f1 100644
--- a/tests/test-vasprintf-posix.c
+++ b/tests/test-vasprintf-posix.c
@@ -21,6 +21,7 @@
 #include <stdio.h>
 
 #include <float.h>
+#include <math.h>
 #include <stdarg.h>
 #include <stddef.h>
 #include <stdio.h>
@@ -40,18 +41,6 @@
     }									     \
   while (0)
 
-/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0.  */
-#ifdef __DECC
-static double
-NaN ()
-{
-  static double zero = 0.0;
-  return zero / zero;
-}
-#else
-# define NaN() (0.0 / 0.0)
-#endif
-
 /* The SGI MIPS floating-point format does not distinguish 0.0 and -0.0.  */
 static int
 have_minus_zero ()
@@ -105,7 +94,7 @@ strisnan (const char *string, size_t start_index, size_t end_index, int uppercas
     }
   return 0;
 }
-	  
+
 static void
 test_function (int (*my_asprintf) (char **, const char *, ...))
 {
@@ -238,7 +227,7 @@ test_function (int (*my_asprintf) (char **, const char *, ...))
   { /* NaN.  */
     char *result;
     int retval =
-      my_asprintf (&result, "%a %d", NaN (), 33, 44, 55);
+      my_asprintf (&result, "%a %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 0)
@@ -471,7 +460,7 @@ test_function (int (*my_asprintf) (char **, const char *, ...))
   { /* FLAG_ZERO with NaN.  */
     char *result;
     int retval =
-      my_asprintf (&result, "%050a %d", NaN (), 33, 44, 55);
+      my_asprintf (&result, "%050a %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     /* "0000000nan 33" is not a valid result; see
        <http://lists.gnu.org/archive/html/bug-gnulib/2007-04/msg00107.html> */
@@ -1067,7 +1056,7 @@ test_function (int (*my_asprintf) (char **, const char *, ...))
   { /* NaN.  */
     char *result;
     int retval =
-      my_asprintf (&result, "%f %d", NaN (), 33, 44, 55);
+      my_asprintf (&result, "%f %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 0)
@@ -1160,7 +1149,7 @@ test_function (int (*my_asprintf) (char **, const char *, ...))
   { /* FLAG_ZERO with NaN.  */
     char *result;
     int retval =
-      my_asprintf (&result, "%050f %d", NaN (), 33, 44, 55);
+      my_asprintf (&result, "%050f %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     ASSERT (strlen (result) == 50 + 3
 	    && strisnan (result, strspn (result, " "), strlen (result) - 3, 0)
@@ -1639,7 +1628,7 @@ test_function (int (*my_asprintf) (char **, const char *, ...))
   { /* NaN.  */
     char *result;
     int retval =
-      my_asprintf (&result, "%F %d", NaN (), 33, 44, 55);
+      my_asprintf (&result, "%F %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 1)
@@ -1978,7 +1967,7 @@ test_function (int (*my_asprintf) (char **, const char *, ...))
   { /* NaN.  */
     char *result;
     int retval =
-      my_asprintf (&result, "%e %d", NaN (), 33, 44, 55);
+      my_asprintf (&result, "%e %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 0)
@@ -2089,7 +2078,7 @@ test_function (int (*my_asprintf) (char **, const char *, ...))
   { /* FLAG_ZERO with NaN.  */
     char *result;
     int retval =
-      my_asprintf (&result, "%050e %d", NaN (), 33, 44, 55);
+      my_asprintf (&result, "%050e %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     ASSERT (strlen (result) == 50 + 3
 	    && strisnan (result, strspn (result, " "), strlen (result) - 3, 0)
@@ -2680,7 +2669,7 @@ test_function (int (*my_asprintf) (char **, const char *, ...))
   { /* NaN.  */
     char *result;
     int retval =
-      my_asprintf (&result, "%g %d", NaN (), 33, 44, 55);
+      my_asprintf (&result, "%g %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     ASSERT (strlen (result) >= 3 + 3
 	    && strisnan (result, 0, strlen (result) - 3, 0)
@@ -2784,7 +2773,7 @@ test_function (int (*my_asprintf) (char **, const char *, ...))
   { /* FLAG_ZERO with NaN.  */
     char *result;
     int retval =
-      my_asprintf (&result, "%050g %d", NaN (), 33, 44, 55);
+      my_asprintf (&result, "%050g %d", NAN, 33, 44, 55);
     ASSERT (result != NULL);
     ASSERT (strlen (result) == 50 + 3
 	    && strisnan (result, strspn (result, " "), strlen (result) - 3, 0)