3 files changed, 13 insertions, 4 deletions
diff --git a/ChangeLog b/ChangeLog
index 12e0831b23..46781b1786 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Fri Aug  5 15:57:10 2011  Naohisa Goto  <ngotogenome@gmail.com>
+
+	* complex.c (f_signbit): fix compile error in gcc4 on Solaris with
+	  CFLAGS="-std=gnu99".  [ruby-dev:44355] fix [Bug #5159]
+
+	* math.c: ditto.
+
 Thu Aug  5 10:09:00 2011  Kenta Murata  <mrkn@mrkn.jp>
 
 	* backport r32846 from trunk.
diff --git a/complex.c b/complex.c
index a21249681f..4be8099ed6 100644
--- a/complex.c
+++ b/complex.c
@@ -1173,8 +1173,9 @@ nucomp_eql_p(VALUE self, VALUE other)
 inline static VALUE
 f_signbit(VALUE x)
 {
-#if defined(HAVE_SIGNBIT) && defined(__GNUC__) && defined(__sun__)
-    extern int signbit(double x);
+#if defined(HAVE_SIGNBIT) && defined(__GNUC__) && defined(__sun__) && \
+    !defined(signbit)
+    extern int signbit(double);
 #endif
     switch (TYPE(x)) {
       case T_FLOAT: {
diff --git a/math.c b/math.c
index 98b327272b..276b2cbc49 100644
--- a/math.c
+++ b/math.c
@@ -14,8 +14,9 @@
 #include <math.h>
 #include <errno.h>
 
-#if defined(HAVE_SIGNBIT) && defined(__GNUC__) && defined(__sun__)
-    extern int signbit(double x);
+#if defined(HAVE_SIGNBIT) && defined(__GNUC__) && defined(__sun__) && \
+    !defined(signbit)
+    extern int signbit(double);
 #endif
 
 #define numberof(array) (int)(sizeof(array) / sizeof((array)[0]))