2 files changed, 19 insertions, 2 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 6131249beb9..f1691252778 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,19 @@
 2011-09-06  Paul Eggert  <eggert@cs.ucla.edu>
 
+        isnan: Fix porting problem to Solaris 10 with bundled gcc.
+        Without this fix, the command to link temacs failed due to an
+        undefined symbol __builtin_isnan.  This is because
+        /usr/include/iso/math_c99.h #defines isnan(x) to
+        __builtin_isnan(x), but the bundled gcc, which identifies itself
+        as gcc 3.4.3 (csl-sol210-3_4-branch+sol_rpath), does not have
+        a __builtin_isnan.
+        * floatfns.c (isnan): #undef, and then #define to a clone of
+        what's in data.c.
+        (Fisnan): Always define, since it's always available now.
+        (syms_of_floatfns): Always define isnan at the Lisp level.
+
+2011-09-06  Paul Eggert  <eggert@cs.ucla.edu>
+
         * Makefile.in (gl-stamp): move-if-change now in build-aux (Bug#9169).
 
 2011-09-06  Paul Eggert  <eggert@cs.ucla.edu>
diff --git a/src/floatfns.c b/src/floatfns.c
index 89aa052e8b1..81cf6bdb61f 100644
--- a/src/floatfns.c
+++ b/src/floatfns.c
@@ -282,7 +282,9 @@ DEFUN ("tan", Ftan, Stan, 1, 1, 0,
   return make_float (d);
 }
 
-#if defined HAVE_ISNAN && defined HAVE_COPYSIGN
+#undef isnan
+#define isnan(x) ((x) != (x))
+
 DEFUN ("isnan", Fisnan, Sisnan, 1, 1, 0,
        doc: /* Return non nil iff argument X is a NaN.  */)
   (Lisp_Object x)
@@ -291,6 +293,7 @@ DEFUN ("isnan", Fisnan, Sisnan, 1, 1, 0,
   return isnan (XFLOAT_DATA (x)) ? Qt : Qnil;
 }
 
+#ifdef HAVE_COPYSIGN
 DEFUN ("copysign", Fcopysign, Scopysign, 1, 2, 0,
        doc: /* Copy sign of X2 to value of X1, and return the result.
 Cause an error if X1 or X2 is not a float.  */)
@@ -1030,8 +1033,8 @@ syms_of_floatfns (void)
   defsubr (&Scos);
   defsubr (&Ssin);
   defsubr (&Stan);
-#if defined HAVE_ISNAN && defined HAVE_COPYSIGN
   defsubr (&Sisnan);
+#ifdef HAVE_COPYSIGN
   defsubr (&Scopysign);
   defsubr (&Sfrexp);
   defsubr (&Sldexp);