Fix finite-math-only lgamma functions signgam setting (bug 19211).

The lgamma inline functions in bits/math-finite.h do not set signgam
if __USE_ISOC99, even when other feature test macros mean a standard
such as XSI POSIX is selected for which it should be set.  (This is
essentially the opposite issue to bug 15421, the out-of-line versions
setting signgam even when they shouldn't.)

This patch fixes those functions to use __USE_MISC || __USE_XOPEN as
the condition for when to set signgam, since it's the condition for
when math.h declares signgam.  The legacy gamma* names are only
declared at all if __USE_MISC || __USE_XOPEN, so they just set signgam
unconditionally.

Tests for certain standards or not using _GNU_SOURCE cannot use
test-skeleton.c (this is a known issue noted on the wiki todo list).
Thus, the new tests that signgam remains not set in ISO C modes do not
use test-skeleton.c.  They also define _ISOMAC to avoid running into
declarations in the internal include/ headers that only work in
_GNU_SOURCE mode.

Tested for x86_64 and x86.

	[BZ #19211]
	* math/bits/math-finite.h (lgamma): Set signgam if [__USE_MISC ||
	__USE_XOPEN], not if [!__USE_ISOC99].
	(lgammaf): Likewise.
	(lgammal): Likewise.
	(gamma): Set signgam unconditionally, not if [!__USE_ISOC99].
	(gammaf): Likewise.
	(gammal): Likewise.
	* math/test-signgam-finite-c11.c: New file.
	* math/test-signgam-finite-c99.c: Likewise.
	* math/test-signgam-finite.c: Likewise.
	* math/Makefile (tests): Add test-signgam-finite,
	test-signgam-finite-c99 and test-signgam-finite-c11.
	(CFLAGS-test-signgam-finite.c): New variable.
	(CFLAGS-test-signgam-finite-c99.c): Likewise.
	(CFLAGS-test-signgam-finite-c11.c): Likewise.

5 files changed, 146 insertions, 25 deletions

diff --git a/math/Makefile b/math/Makefile
index 3efbc58d5c..adeb806e3f 100644
--- a/math/Makefile
+++ b/math/Makefile
@@ -108,7 +108,8 @@ tests = test-matherr test-fenv atest-exp atest-sincos atest-exp2 basic-test \
 	test-tgmath-ret bug-nextafter bug-nexttoward bug-tgmath1 \
 	test-tgmath-int test-tgmath2 test-powl tst-CMPLX tst-CMPLX2 test-snan \
 	test-fenv-tls test-fenv-preserve test-fenv-return test-fenvinline \
-	test-nearbyint-except test-fenv-clear $(tests-static)
+	test-nearbyint-except test-fenv-clear test-signgam-finite \
+	test-signgam-finite-c99 test-signgam-finite-c11 $(tests-static)
 tests-static = test-fpucw-static test-fpucw-ieee-static
 # We do the `long double' tests only if this data type is available and
 # distinct from `double'.
@@ -185,6 +186,10 @@ CPPFLAGS-test-idouble.c = -U__LIBC_INTERNAL_MATH_INLINES \
 CPPFLAGS-test-ildoubl.c = -U__LIBC_INTERNAL_MATH_INLINES \
 			  $(libm-test-fast-math-cflags)
 
+CFLAGS-test-signgam-finite.c = -ffinite-math-only
+CFLAGS-test-signgam-finite-c99.c = -ffinite-math-only -std=c99
+CFLAGS-test-signgam-finite-c11.c = -ffinite-math-only -std=c11
+
 # The -lieee module sets the _LIB_VERSION_ switch to IEEE mode
 # for error handling in the -lm functions.
 install-lib += libieee.a
diff --git a/math/bits/math-finite.h b/math/bits/math-finite.h
index 5dd8406588..e3f93bd239 100644
--- a/math/bits/math-finite.h
+++ b/math/bits/math-finite.h
@@ -307,32 +307,32 @@ extern long double __lgammal_r_finite (long double, int *);
 /* lgamma.  */
 __extern_always_inline double __NTH (lgamma (double __d))
 {
-# ifdef __USE_ISOC99
+# if defined __USE_MISC || defined __USE_XOPEN
+  return __lgamma_r_finite (__d, &signgam);
+# else
   int __local_signgam = 0;
   return __lgamma_r_finite (__d, &__local_signgam);
-# else
-  return __lgamma_r_finite (__d, &signgam);
 # endif
 }
 #endif
 #if defined __USE_ISOC99 && defined __extern_always_inline
 __extern_always_inline float __NTH (lgammaf (float __d))
 {
-# ifdef __USE_ISOC99
+# if defined __USE_MISC || defined __USE_XOPEN
+  return __lgammaf_r_finite (__d, &signgam);
+# else
   int __local_signgam = 0;
   return __lgammaf_r_finite (__d, &__local_signgam);
-# else
-  return __lgammaf_r_finite (__d, &signgam);
 # endif
 }
 # ifdef __MATH_DECLARE_LDOUBLE
 __extern_always_inline long double __NTH (lgammal (long double __d))
 {
-# ifdef __USE_ISOC99
+# if defined __USE_MISC || defined __USE_XOPEN
+  return __lgammal_r_finite (__d, &signgam);
+# else
   int __local_signgam = 0;
   return __lgammal_r_finite (__d, &__local_signgam);
-# else
-  return __lgammal_r_finite (__d, &signgam);
 # endif
 }
 # endif
@@ -343,32 +343,17 @@ __extern_always_inline long double __NTH (lgammal (long double __d))
 /* gamma.  */
 __extern_always_inline double __NTH (gamma (double __d))
 {
-# ifdef __USE_ISOC99
-  int __local_signgam = 0;
-  return __lgamma_r_finite (__d, &__local_signgam);
-# else
   return __lgamma_r_finite (__d, &signgam);
-# endif
 }
 # ifdef __USE_ISOC99
 __extern_always_inline float __NTH (gammaf (float __d))
 {
-#  ifdef __USE_ISOC99
-  int __local_signgam = 0;
-  return __lgammaf_r_finite (__d, &__local_signgam);
-#  else
   return __lgammaf_r_finite (__d, &signgam);
-#  endif
 }
 #  ifdef __MATH_DECLARE_LDOUBLE
 __extern_always_inline long double __NTH (gammal (long double __d))
 {
-#   ifdef __USE_ISOC99
-  int __local_signgam = 0;
-  return __lgammal_r_finite (__d, &__local_signgam);
-#   else
   return __lgammal_r_finite (__d, &signgam);
-#   endif
 }
 #  endif
 # endif
diff --git a/math/test-signgam-finite-c11.c b/math/test-signgam-finite-c11.c
new file mode 100644
index 0000000000..dff132df93
--- /dev/null
+++ b/math/test-signgam-finite-c11.c
@@ -0,0 +1 @@
+#include "test-signgam-finite-c99.c"
diff --git a/math/test-signgam-finite-c99.c b/math/test-signgam-finite-c99.c
new file mode 100644
index 0000000000..bdbaf5a13c
--- /dev/null
+++ b/math/test-signgam-finite-c99.c
@@ -0,0 +1,65 @@
+/* Test lgamma functions do not set signgam for -ffinite-math-only for ISO C.
+   Copyright (C) 2015 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#undef _LIBC
+#undef _GNU_SOURCE
+#define _ISOMAC
+
+#include <math.h>
+#include <stdio.h>
+
+int signgam;
+
+#define RUN_TESTS(FUNC, TYPE)					\
+  do								\
+    {								\
+      volatile TYPE a, b, c __attribute__ ((unused));		\
+      a = 0.5;							\
+      b = -0.5;							\
+      signgam = 123;						\
+      c = FUNC (a);						\
+      if (signgam == 123)					\
+	puts ("PASS: " #FUNC " (0.5) setting signgam");		\
+      else							\
+	{							\
+	  puts ("FAIL: " #FUNC " (0.5) setting signgam");	\
+	  result = 1;						\
+	}							\
+      signgam = 123;						\
+      c = FUNC (b);						\
+      if (signgam == 123)					\
+	puts ("PASS: " #FUNC " (0.5) setting signgam");		\
+      else							\
+	{							\
+	  puts ("FAIL: " #FUNC " (0.5) setting signgam");	\
+	  result = 1;						\
+	}							\
+    }								\
+  while (0)
+
+int
+main (void)
+{
+  int result = 0;
+  RUN_TESTS (lgammaf, float);
+  RUN_TESTS (lgamma, double);
+#ifndef NO_LONG_DOUBLE
+  RUN_TESTS (lgammal, long double);
+#endif
+  return result;
+}
diff --git a/math/test-signgam-finite.c b/math/test-signgam-finite.c
new file mode 100644
index 0000000000..5d444c8068
--- /dev/null
+++ b/math/test-signgam-finite.c
@@ -0,0 +1,65 @@
+/* Test lgamma functions set signgam for -ffinite-math-only (bug 19211).
+   Copyright (C) 2015 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <math.h>
+#include <stdio.h>
+
+#define RUN_TESTS(FUNC, TYPE)					\
+  do								\
+    {								\
+      volatile TYPE a, b, c __attribute__ ((unused));		\
+      a = 0.5;							\
+      b = -0.5;							\
+      signgam = 123;						\
+      c = FUNC (a);						\
+      if (signgam == 1)						\
+	puts ("PASS: " #FUNC " (0.5) setting signgam");		\
+      else							\
+	{							\
+	  puts ("FAIL: " #FUNC " (0.5) setting signgam");	\
+	  result = 1;						\
+	}							\
+      signgam = 123;						\
+      c = FUNC (b);						\
+      if (signgam == -1)					\
+	puts ("PASS: " #FUNC " (0.5) setting signgam");		\
+      else							\
+	{							\
+	  puts ("FAIL: " #FUNC " (0.5) setting signgam");	\
+	  result = 1;						\
+	}							\
+    }								\
+  while (0)
+
+static int
+do_test (void)
+{
+  int result = 0;
+  RUN_TESTS (lgammaf, float);
+  RUN_TESTS (gammaf, float);
+  RUN_TESTS (lgamma, double);
+  RUN_TESTS (gamma, double);
+#ifndef NO_LONG_DOUBLE
+  RUN_TESTS (lgammal, long double);
+  RUN_TESTS (gammal, long double);
+#endif
+  return result;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"