| Message ID | 20200902191326.GA1852830@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: Stop defining true, false and bool as macros in <stdbool.h> | expand |
On 9/2/20 3:13 PM, Jonathan Wakely wrote: > Since r216679 these macros have only been defined in C++98 mode, rather > than all modes. That is permitted as a GNU extension because that header > doesn't exist in the C++ standard until C++11, so we can make it do > whatever we want for C++98. But as discussed in the PR c++/60304 > comments, these macros shouldn't ever be defined for C++. > > This patch removes the macro definitions for C++98 too. > > The new test already passed for C++98 (and the conversion is ill-formed > in C++11 and later) so this new test is arguably unnecessary. > > gcc/ChangeLog: > > PR c++/60304 > * ginclude/stdbool.h (bool, false, true): Never define for C++. > > gcc/testsuite/ChangeLog: > > PR c++/60304 > * g++.dg/warn/Wconversion-null-5.C: New test. > > > Back in 2012 Gerald argued that we should keep these macros in case > there is code depending on them. We've not been defining them in C++11 > and later modes (including our default -std=gnu++14) for nearly six > years now (GCC 5.1 shipped with the change). I'm not aware of any > reports of problems. I think it's time to stop defining them at all. > > Bootstrapped and tested on powerpc64le-linux, OK for trunk? seems reasonable, thanks
diff --git a/gcc/ginclude/stdbool.h b/gcc/ginclude/stdbool.h index 72be438692f..1b56498d96f 100644 --- a/gcc/ginclude/stdbool.h +++ b/gcc/ginclude/stdbool.h @@ -39,13 +39,6 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see /* 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 */ /* Signal that all the definitions are present. */ diff --git a/gcc/testsuite/g++.dg/warn/Wconversion-null-5.C b/gcc/testsuite/g++.dg/warn/Wconversion-null-5.C new file mode 100644 index 00000000000..05980ea91ab --- /dev/null +++ b/gcc/testsuite/g++.dg/warn/Wconversion-null-5.C @@ -0,0 +1,6 @@ +// PR c++/60304 +// { dg-do compile { target c++98_only } } +// { dg-options "-Wconversion-null" } + +#include <stdbool.h> +int * foo() {return false;} // { dg-warning "converting 'false' to pointer" }
Since r216679 these macros have only been defined in C++98 mode, rather than all modes. That is permitted as a GNU extension because that header doesn't exist in the C++ standard until C++11, so we can make it do whatever we want for C++98. But as discussed in the PR c++/60304 comments, these macros shouldn't ever be defined for C++. This patch removes the macro definitions for C++98 too. The new test already passed for C++98 (and the conversion is ill-formed in C++11 and later) so this new test is arguably unnecessary. gcc/ChangeLog: PR c++/60304 * ginclude/stdbool.h (bool, false, true): Never define for C++. gcc/testsuite/ChangeLog: PR c++/60304 * g++.dg/warn/Wconversion-null-5.C: New test. Back in 2012 Gerald argued that we should keep these macros in case there is code depending on them. We've not been defining them in C++11 and later modes (including our default -std=gnu++14) for nearly six years now (GCC 5.1 shipped with the change). I'm not aware of any reports of problems. I think it's time to stop defining them at all. Bootstrapped and tested on powerpc64le-linux, OK for trunk? commit f049cda373d29ea1bce4065b24cbb392cdc5b172 Author: Jonathan Wakely <jwakely@redhat.com> Date: Wed Sep 2 18:51:28 2020 c++: Stop defining true, false and bool as macros in <stdbool.h> Since r216679 these macros have only been defined in C++98 mode, rather than all modes. That is permitted as a GNU extension because that header doesn't exist in the C++ standard until C++11, so we can make it do whatever we want for C++98. But as discussed in the PR c++/60304 comments, these macros shouldn't ever be defined for C++. This patch removes the macro definitions for C++98 too. The new test already passed for C++98 (and the conversion is ill-formed in C++11 and later) so this new test is arguably unnecessary. gcc/ChangeLog: PR c++/60304 * ginclude/stdbool.h (bool, false, true): Never define for C++. gcc/testsuite/ChangeLog: PR c++/60304 * g++.dg/warn/Wconversion-null-5.C: New test.