Patchwork <stdbool.h> should not define bool, true or false as macros for C++

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Submitter Jonathan Wakely
Date Feb. 5, 2012, 1 p.m.
Message ID <CAH6eHdR03TKR2aq9eA3MwnkT+ONVA7_x63_ZDMp_ub9JGV1S-w@mail.gmail.com>
Download mbox | patch
Permalink /patch/139639/
State New
Headers show

Comments

Jonathan Wakely - Feb. 5, 2012, 1 p.m.
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?

Patch

diff --git a/gcc/ginclude/stdbool.h b/gcc/ginclude/stdbool.h
index 4ed911f..4645654 100644
--- a/gcc/ginclude/stdbool.h
+++ b/gcc/ginclude/stdbool.h
@@ -1,4 +1,4 @@ 
-/* Copyright (C) 1998, 1999, 2000, 2009 Free Software Foundation, Inc.
+/* Copyright (C) 1998, 1999, 2000, 2009, 2012 Free Software Foundation, Inc.
 
 This file is part of GCC.
 
@@ -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
+