| Message ID | 20160118162856.GY15084@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Mon, 18 Jan 2016, Jonathan Wakely wrote: > This fixes PR60637 by using the appropriate built-in for the size of > the argument type. In Bugzilla Marc asked why we don't just use the > same code as for C++11, but I want to make this less intrusive change > on the branches (trunk is already OK anyway). That's fine for the branch indeed, but I don't see why we couldn't remove that illegal signbit declaration on trunk in C++98 mode. It works but it is still wrong to have it. Now that C++14 is the default, explicitly asking for C++98 looks like a clear sign to me that people don't want such extensions.
On 18/01/16 21:24 +0100, Marc Glisse wrote: >On Mon, 18 Jan 2016, Jonathan Wakely wrote: > >>This fixes PR60637 by using the appropriate built-in for the size of >>the argument type. In Bugzilla Marc asked why we don't just use the >>same code as for C++11, but I want to make this less intrusive change >>on the branches (trunk is already OK anyway). > >That's fine for the branch indeed, but I don't see why we couldn't >remove that illegal signbit declaration on trunk in C++98 mode. It >works but it is still wrong to have it. Now that C++14 is the default, >explicitly asking for C++98 looks like a clear sign to me that people >don't want such extensions. For -std=c++98 rather than -std=gnu++98 I agree, but I'm not going to make that change in stage 3, let's do it in stage 1. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69350
commit e30df471f94c383d742bf4506a794b6505526f77
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Mon Jan 18 14:39:57 2016 +0000
Fix C++98 std::signbit<long double>
PR libstdc++/60637
* include/c_global/cmath (signbit) [__cplusplus < 201103L]: Use
__builtin_signbitf or __builtin_signbitl as appropriate.
* testsuite/26_numerics/headers/cmath/60637.cc: New.
diff --git a/libstdc++-v3/include/c_global/cmath b/libstdc++-v3/include/c_global/cmath
index 4cafe5f..d3fc8b7 100644
--- a/libstdc++-v3/include/c_global/cmath
+++ b/libstdc++-v3/include/c_global/cmath
@@ -880,7 +880,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
signbit(_Tp __f)
{
typedef typename __gnu_cxx::__promote<_Tp>::__type __type;
- return __builtin_signbit(__type(__f));
+ return sizeof(__type) == sizeof(float)
+ ? __builtin_signbitf(__type(__f))
+ : sizeof(__type) == sizeof(double)
+ ? __builtin_signbit(__type(__f))
+ : __builtin_signbitl(__type(__f));
}
template<typename _Tp>
diff --git a/libstdc++-v3/testsuite/26_numerics/headers/cmath/60637.cc b/libstdc++-v3/testsuite/26_numerics/headers/cmath/60637.cc
new file mode 100644
index 0000000..16a7896
--- /dev/null
+++ b/libstdc++-v3/testsuite/26_numerics/headers/cmath/60637.cc
@@ -0,0 +1,35 @@
+// Copyright (C) 2016 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This 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 General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++98 -ffast-math" }
+// { dg-do run { target i?86-*-* x86_64-*-* } }
+
+#include <cmath>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+ long double ld = -5.3165867831218916301793863361917824e-2467L;
+ VERIFY( std::signbit(ld) == 1 );
+}
+
+int
+main()
+{
+ test01();
+}