Check against a bug of frexp() on IRIX 6.5.

diff --git a/ChangeLog b/ChangeLog
index 20ffd3fb22efa38aaed3d7643c05af8ebb4fc545..532ae780aac3ecd063bea0a370740dbf3f708b48 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2007-03-25  Bruno Haible  <bruno@clisp.org>
+
+       * m4/frexp.m4 (gl_FUNC_FREXP_WORKS): Add check whether frexp(inf)
+       returns inf. Needed on IRIX 6.5.
+
 2007-03-25  Bruno Haible  <bruno@clisp.org>
 
        * tests/test-frexpl.c: Include isnanl-nolibm.h.

diff --git a/m4/frexp.m4 b/m4/frexp.m4
index 60d897b89c56c4786ee7411d0b3a71833e958a5b..88d5be6e30447bee2624047bec5daa83997ddf16 100644 (file)
--- a/m4/frexp.m4
+++ b/m4/frexp.m4
@@ -1,4 +1,4 @@
-# frexp.m4 serial 1
+# frexp.m4 serial 2
 dnl Copyright (C) 2007 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -55,8 +55,8 @@ AC_DEFUN([gl_FUNC_FREXP],
   fi
 ])
 
-dnl Test whether frexp() works also on denormalized numbers.
-dnl This test fails e.g. on NetBSD.
+dnl Test whether frexp() works also on denormalized numbers (this fails e.g. on
+dnl NetBSD 3.0) and on infinite numbers (this fails e.g. on IRIX 6.5).
 AC_DEFUN([gl_FUNC_FREXP_WORKS],
 [
   AC_REQUIRE([AC_PROG_CC])
@@ -70,6 +70,7 @@ int main()
 {
   int i;
   volatile double x;
+  /* Test on denormalized numbers.  */
   for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5)
     ;
   if (x > 0.0)
@@ -81,11 +82,19 @@ int main()
       if (y != 0.5)
         return 1;
     }
+  /* Test on infinite numbers.  */
+  {
+    x = 1.0 / 0.0;
+    int exp;
+    double y = frexp (x, &exp);
+    if (y != x)
+      return 1;
+  }
   return 0;
 }], [gl_cv_func_frexp_works=yes], [gl_cv_func_frexp_works=no],
       [case "$host_os" in
-         netbsd*) gl_cv_func_frexp_works="guessing no";;
-         *)       gl_cv_func_frexp_works="guessing yes";;
+         netbsd* | irix*) gl_cv_func_frexp_works="guessing no";;
+         *)               gl_cv_func_frexp_works="guessing yes";;
        esac
       ])
     ])