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Re: [PATCH] Define iszero as a function template for C++ [BZ #20715]
On 10/21/2016 06:23 PM, Joseph Myers wrote:
On Fri, 21 Oct 2016, Florian Weimer wrote:
On 10/21/2016 06:12 PM, Joseph Myers wrote:
On Fri, 21 Oct 2016, Florian Weimer wrote:
Tested on x86_64, ppc64, ppc64le, s390x, aarch64.
I'm not sure if the new test is particularly meaningful, but at least it
catches syntax errors in <math.h>.
This seems fine to me (with negative zero included in the testcase),
Oh. How do I get a negative zero? Would T{-0.0} be sufficient? Or should I
Yes, T{-0.0} or -T{0} should suffice.
Thanks. Here is what I've committed. Everything is optimized away
anyway (but I deliberately introduced a bug to make sure the test still
tests something).
Florian
math: Define iszero as a function template for C++ [BZ #20715]
This increases compatibility with C++ code which is forced to
compile with _GNU_SOURCE.
2016-10-21 Florian Weimer <fweimer@redhat.com>
[BZ #20715]
* math/math.h [__cplusplus] (iszero): Define as function template.
* math/Makefile [CXX] (tests): Add test-math-iszero.
(CFLAGS-test-math-iszero.cc): Set.
* math/test-math-iszero.cc: New file.
diff --git a/math/Makefile b/math/Makefile
index 2aa6a34..7cecba5 100644
--- a/math/Makefile
+++ b/math/Makefile
@@ -165,7 +165,7 @@ tests-static = test-fpucw-static test-fpucw-ieee-static \
test-signgam-ullong-static test-signgam-ullong-init-static
ifneq (,$(CXX))
-tests += test-math-isinff
+tests += test-math-isinff test-math-iszero
endif
ifneq (no,$(PERL))
@@ -267,6 +267,7 @@ CFLAGS-test-signgam-ullong-static.c = -std=c99
CFLAGS-test-signgam-ullong-init-static.c = -std=c99
CFLAGS-test-math-isinff.cc = -std=gnu++11
+CFLAGS-test-math-iszero.cc = -std=gnu++11
CFLAGS-test-iszero-excess-precision.c = -fexcess-precision=standard
CFLAGS-test-iseqsig-excess-precision.c = -fexcess-precision=standard
diff --git a/math/math.h b/math/math.h
index 880b4a0..0220d08 100644
--- a/math/math.h
+++ b/math/math.h
@@ -335,11 +335,25 @@ enum
# define issubnormal(x) (fpclassify (x) == FP_SUBNORMAL)
/* Return nonzero value if X is zero. */
-# ifdef __SUPPORT_SNAN__
-# define iszero(x) (fpclassify (x) == FP_ZERO)
-# else
-# define iszero(x) (((__typeof (x)) (x)) == 0)
-# endif
+# ifndef __cplusplus
+# ifdef __SUPPORT_SNAN__
+# define iszero(x) (fpclassify (x) == FP_ZERO)
+# else
+# define iszero(x) (((__typeof (x)) (x)) == 0)
+# endif
+# else /* __cplusplus */
+__END_DECLS
+template <class __T> inline bool
+iszero (__T __val)
+{
+# ifdef __SUPPORT_SNAN__
+ return fpclassify (__val) == FP_ZERO;
+# else
+ return __val == 0;
+# endif
+}
+__BEGIN_DECLS
+# endif /* __cplusplus */
#endif /* Use IEC_60559_BFP_EXT. */
#ifdef __USE_MISC
diff --git a/math/test-math-iszero.cc b/math/test-math-iszero.cc
new file mode 100644
index 0000000..5de251a
--- /dev/null
+++ b/math/test-math-iszero.cc
@@ -0,0 +1,87 @@
+/* Test for the C++ implementation of iszero.
+ Copyright (C) 2016 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/>. */
+
+#define _GNU_SOURCE 1
+#include <math.h>
+#include <stdio.h>
+
+#include <limits>
+
+static bool errors;
+
+static void
+check (int actual, int expected, const char *actual_expr, int line)
+{
+ if (actual != expected)
+ {
+ errors = true;
+ printf ("%s:%d: error: %s\n", __FILE__, line, actual_expr);
+ printf ("%s:%d: expected: %d\n", __FILE__, line, expected);
+ printf ("%s:%d: actual: %d\n", __FILE__, line, actual);
+ }
+}
+
+#define CHECK(actual, expected) \
+ check ((actual), (expected), #actual, __LINE__)
+
+template <class T>
+static void
+check_type ()
+{
+ typedef std::numeric_limits<T> limits;
+ CHECK (iszero (T{}), 1);
+ CHECK (iszero (T{0}), 1);
+ CHECK (iszero (T{-0.0}), 1);
+ CHECK (iszero (T{1}), 0);
+ CHECK (iszero (T{-1}), 0);
+ CHECK (iszero (limits::min ()), 0);
+ CHECK (iszero (-limits::min ()), 0);
+ CHECK (iszero (limits::max ()), 0);
+ CHECK (iszero (-limits::max ()), 0);
+ if (limits::has_infinity)
+ {
+ CHECK (iszero (limits::infinity ()), 0);
+ CHECK (iszero (-limits::infinity ()), 0);
+ }
+ CHECK (iszero (limits::epsilon ()), 0);
+ CHECK (iszero (-limits::epsilon ()), 0);
+ if (limits::has_quiet_NaN)
+ CHECK (iszero (limits::quiet_NaN ()), 0);
+ if (limits::has_signaling_NaN)
+ CHECK (iszero (limits::signaling_NaN ()), 0);
+ if (limits::has_signaling_NaN)
+ CHECK (iszero (limits::signaling_NaN ()), 0);
+ CHECK (iszero (limits::denorm_min ()),
+ std::numeric_limits<T>::has_denorm == std::denorm_absent);
+ CHECK (iszero (-limits::denorm_min ()),
+ std::numeric_limits<T>::has_denorm == std::denorm_absent);
+}
+
+static int
+do_test (void)
+{
+ check_type<float> ();
+ check_type<double> ();
+#ifndef NO_LONG_DOUBLE
+ check_type<long double> ();
+#endif
+ return errors;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"