lgamma: fix sign handling

add testcase from
http://sourceware.org/bugzilla/show_bug.cgi?id=4407

Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

2 files changed, 20 insertions, 1 deletions

diff --git a/test/math/Makefile.in b/test/math/Makefile.in
index b160c875d..8a46e77db 100644
--- a/test/math/Makefile.in
+++ b/test/math/Makefile.in
@@ -1,7 +1,7 @@
 # uClibc math tests
 # Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
 
-TESTS := basic-test rint tst-definitions test-fpucw test-float test-ifloat test-double test-idouble
+TESTS := basic-test rint signgam tst-definitions test-fpucw test-float test-ifloat test-double test-idouble
 ifeq ($(UCLIBC_HAS_LONG_DOUBLE_MATH),y)
 TESTS += test-ldouble test-ildoubl compile_test
 else
@@ -9,6 +9,7 @@ CFLAGS_basic-test := -DNO_LONG_DOUBLE
 endif
 
 DODIFF_rint     := 1
+DODIFF_signgam  := 1
 
 # NOTE: For basic-test we must disable the floating point optimization.
 #       Only for sh architecture because in the other architecture are disabled.
diff --git a/test/math/signgam.c b/test/math/signgam.c
new file mode 100644
index 000000000..c60375aec
--- /dev/null
+++ b/test/math/signgam.c
@@ -0,0 +1,18 @@
+#define _XOPEN_SOURCE 600
+#include <math.h>
+#include <stdio.h>
+
+double zero = 0.0;
+double mzero;
+
+int
+main (void)
+{
+  double d;
+  mzero = copysign (zero, -1.0);
+  d = lgamma (zero);
+  printf ("%g %d\n", d, signgam);
+  d = lgamma (mzero);
+  printf ("%g %d\n", d, signgam);
+  return 0;
+}