I want to resurrect this patch that I didn't pursue for 4.8, because
our <stdbool.h> violates this very explicit requirement in the C++11
and C++14 standards:
18.10 [support.runtime] p8
"The header <cstdbool> and the header <stdbool.h> shall not define
macros named bool, true, or false."
Is the gcc/ginclude/stdbool.h change OK for trunk?
Tested x86_64-linux. I also looked in the Debian Code Search and it
seems that all the code which cares whether bool is a macro follows
one of these patterns:
#ifdef bool
#undef bool
#ifdef bool
/* Leave if macro is from C99 stdbool.h */
#ifndef __bool_true_false_are_defined
#undef bool
(The __bool_true_false_are_defined macro *is* defined in C++)
#ifdef bool
#error bool should not be defined
#endif
(That's in the libc++ testsuite for <stdbool.h>, we fail that test obviously)
#ifdef bool
#define HAS_BOOL
#endif
So although that search only covers FOSS code I don't think we're
going to break much C++ code by doing this, and it's needed for C++11
anyway.
On 5 February 2012 13:00, Jonathan Wakely wrote:
> On 4 February 2012 23:35, Gerald Pfeifer wrote:
>> For what it's worth, I strongly suggest that you only define those when
>> __cpluplus is pre-C++11.
>>
>> There is simply too much software out there which will run into this
>
> Really? Why would any C++ code assume "bool" is defined as a macro?
> It's been a keyword in C++ for longer than C99 has defined it as a macro.
>
>> and being aggressive in breaking (admittedly non-standard confirming
>> programs) gives GCC a bad reputation and is not nice to our users to
>> begin with.
>
> Fair enough, this revised patch still defines bool, true and false for
> C++98 mode, but not for C++11 mode.
>
> gcc/
> * ginclude/stdbool.h (true, false, bool): Do not define for C++11.
>
> libstdc++/
> * testsuite/18_support/headers/cstdbool/macros.cc: New.
>
> Tested x86_64-linux, OK for trunk?
commit 4c76750dfd43a8102ee3de5ea0c5699be3359d7f
Author: Jonathan Wakely <[email protected]>
Date: Fri Oct 24 10:50:27 2014 +0100
C++11 explicitly forbids macros for bool, true and false.
gcc:
* ginclude/stdbool.h: Do not define bool, true or false in C++11.
libstdc++-v3:
* testsuite/18_support/headers/cstdbool/macros.cc: New.
diff --git a/gcc/ginclude/stdbool.h b/gcc/ginclude/stdbool.h
index f4e802f..a06f17f2 100644
--- a/gcc/ginclude/stdbool.h
+++ b/gcc/ginclude/stdbool.h
@@ -36,11 +36,15 @@ see the files COPYING3 and COPYING.RUNTIME respectively.
If not, see
#else /* __cplusplus */
-/* Supporting <stdbool.h> in C++ is a GCC extension. */
+/* Supporting _Bool in C++ is a GCC extension. */
#define _Bool bool
+
+#if __cplusplus < 201103L
+/* Defining these macros in C++98 is a GCC extension. */
#define bool bool
#define false false
#define true true
+#endif
#endif /* __cplusplus */
diff --git a/libstdc++-v3/testsuite/18_support/headers/cstdbool/macros.cc
b/libstdc++-v3/testsuite/18_support/headers/cstdbool/macros.cc
new file mode 100644
index 0000000..58631d8
--- /dev/null
+++ b/libstdc++-v3/testsuite/18_support/headers/cstdbool/macros.cc
@@ -0,0 +1,38 @@
+// { dg-do compile }
+// { dg-options "-std=gnu++11" }
+
+// Copyright (C) 2012 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/>.
+
+#include <cstdbool>
+
+#ifndef __bool_true_false_are_defined
+# error "The header <cstdbool> fails to define a macro named
__bool_true_false_are_defined"
+#endif
+
+#ifdef bool
+# error "The header <cstdbool> defines a macro named bool"
+#endif
+
+#ifdef true
+# error "The header <cstdbool> defines a macro named true"
+#endif
+
+#ifdef false
+# error "The header <cstdbool> defines a macro named false"
+#endif
+
