Re: [PATCH v2] environ-selftests: Ignore -Wself-move warning

Simon Marchi
2017-06-22T10:57:16Z

On 2017-06-22 12:52, Pedro Alves wrote:
> On 06/22/2017 10:51 AM, Pedro Alves wrote:
>> On 06/22/2017 09:31 AM, Simon Marchi wrote:
>>> +#if defined (__clang__)
>>> +
>>> +#define DIAG_PUSH_IGNORE_SELF_MOVE \
>>> + _Pragma("clang diagnostic push") \
>>> + _Pragma("clang diagnostic ignored \"-Wself-move\"")
>>> +#define DIAG_POP_IGNORE_SELF_MOVE _Pragma("clang diagnostic pop")
>>> +
>>> +#else
>>> +
>>> +#define DIAG_PUSH_IGNORE_SELF_MOVE
>>> +#define DIAG_POP_IGNORE_SELF_MOVE
>>> +
>>> +#endif
>>
>>
>> Let me try writing a quick patch that puts a "STRINGIZE" macro
>> in common/preprocessor.h, so we can write the above like I had
>> suggested before, which is a bit more generic. There are several
>> copies in the tree of such a macro, so that'll be a good thing
>> on its own anyway, IMO.
>>
>> I'm not sure whether the single push-ignore macro is a good idea,
>> since if we follow the pattern going forward, it requires more
>> boilerplace if we need different warnings around the same code:
>
> This is what I had in mind. I think it should work with clang,
> though I haven't tried it.
>
>
> Subject: [PATCH] environ-selftests: Ignore -Wself-move warning
>
> ---
> gdb/common/diagnostics.h | 40
> +++++++++++++++++++++++++++++++++++++++
> gdb/unittests/environ-selftests.c | 8 ++++++++
> 2 files changed, 48 insertions(+)
> create mode 100644 gdb/common/diagnostics.h
>
> diff --git a/gdb/common/diagnostics.h b/gdb/common/diagnostics.h
> new file mode 100644
> index 0000000..5a63bfd
> --- /dev/null
> +++ b/gdb/common/diagnostics.h
> @@ -0,0 +1,40 @@
> +/* Copyright (C) 2017 Free Software Foundation, Inc.
> +
> + This file is part of GDB.
> +
> + This program 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 of the License, or
> + (at your option) any later version.
> +
> + This program 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 program. If not, see
> <http://www.gnu.org/licenses/>. */
> +
> +#ifndef COMMON_DIAGNOSTICS_H
> +#define COMMON_DIAGNOSTICS_H
> +
> +#include "common/preprocessor.h"
> +
> +#ifdef __GNUC__
> +# define DIAGNOSTIC_PUSH _Pragma ("GCC diagnostic push")
> +# define DIAGNOSTIC_POP _Pragma ("GCC diagnostic pop")
> +# define DIAGNOSTIC_IGNORE(option) \
> + _Pragma (STRINGIFY (GCC diagnostic ignored option))
> +#else
> +# define DIAGNOSTIC_PUSH
> +# define DIAGNOSTIC_POP
> +# define DIAGNOSTIC_IGNORE(option)
> +#endif
> +
> +#ifdef __clang__
> +# define DIAGNOSTIC_IGNORE_SELF_MOVE DIAGNOSTIC_IGNORE ("-Wself-move")
> +#else
> +# define DIAGNOSTIC_IGNORE_SELF_MOVE
> +#endif
> +
> +#endif /* COMMON_DIAGNOSTICS_H */
> diff --git a/gdb/unittests/environ-selftests.c
> b/gdb/unittests/environ-selftests.c
> index ecc3955..28b16f8 100644
> --- a/gdb/unittests/environ-selftests.c
> +++ b/gdb/unittests/environ-selftests.c
> @@ -20,6 +20,7 @@
> #include "defs.h"
> #include "selftest.h"
> #include "common/environ.h"
> +#include "common/diagnostics.h"
>
> namespace selftests {
> namespace gdb_environ_tests {
> @@ -136,7 +137,14 @@ run_tests ()
> env.clear ();
> env.set ("A", "1");
> SELF_CHECK (strcmp (env.get ("A"), "1") == 0);
> +
> + /* Some compilers warn about moving to self, but that's precisely
> what we want
> + to test here, so turn this warning off. */
> + DIAGNOSTIC_PUSH
> + DIAGNOSTIC_IGNORE_SELF_MOVE
> env = std::move (env);
> + DIAGNOSTIC_POP
> +
> SELF_CHECK (strcmp (env.get ("A"), "1") == 0);
> SELF_CHECK (strcmp (env.envp ()[0], "A=1") == 0);
> SELF_CHECK (env.envp ()[1] == NULL);

I didn't understand how it would work to conditionally define the pragma
based on the compiler, but now that I see it I understand. LTGM.