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binutils-gdb/gdb/common/preprocessor.h

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Make sect_offset and cu_offset strong typedefs instead of structs A while ago, back when GDB was a C program, the sect_offset and cu_offset types were made structs in order to prevent incorrect mixing of those offsets. Now that we require C++11, we can make them integers again, while keeping the safety, by exploiting "enum class". We can add a bit more safety, even, by defining operators that the types _should_ support, helping making the suspicious uses stand out more. Getting at the underlying type is done with the new to_underlying function added by the previous patch, which also helps better spot where do we need to step out of the safety net. Mostly, that's around parsing the DWARF, and when we print the offset for complaint/debug purposes. But there are other occasional uses. Since we have to define the sect_offset/cu_offset types in a header anyway, I went ahead and generalized/library-fied the idea of "offset" types, making it trivial to add more such types if we find a use. See common/offset-type.h and the DEFINE_OFFSET_TYPE macro. I needed a couple generaly-useful preprocessor bits (e.g., yet another CONCAT implementation), so I started a new common/preprocessor.h file. I included units tests covering the "offset" types API. These are mostly compile-time tests, using SFINAE to check that expressions that shouldn't compile (e.g., comparing unrelated offset types) really are invalid and would fail to compile. This same idea appeared in my pending enum-flags revamp from a few months ago (though this version is a bit further modernized compared to what I had posted), and I plan on reusing the "check valid expression" bits added here in that series, so I went ahead and defined the CHECK_VALID_EXPR macro in its own header -- common/valid-expr.h. I think that's nicer regardless. I was borderline between calling the new types "offset" types, or "index" types, BTW. I stuck with "offset" simply because that's what we're already calling them, mostly. gdb/ChangeLog: 2017-04-04 Pedro Alves <palves@redhat.com> * Makefile.in (SUBDIR_UNITTESTS_SRCS): Add unittests/offset-type-selftests.c. (SUBDIR_UNITTESTS_OBS): Add offset-type-selftests.o. * common/offset-type.h: New file. * common/preprocessor.h: New file. * common/traits.h: New file. * common/valid-expr.h: New file. * dwarf2expr.c: Include "common/underlying.h". Adjust to use sect_offset and cu_offset strong typedefs throughout. * dwarf2expr.h: Adjust to use sect_offset and cu_offset strong typedefs throughout. * dwarf2loc.c: Include "common/underlying.h". Adjust to use sect_offset and cu_offset strong typedefs throughout. * dwarf2read.c: Adjust to use sect_offset and cu_offset strong typedefs throughout. * gdbtypes.h: Include "common/offset-type.h". (cu_offset): Now an offset type (strong typedef) instead of a struct. (sect_offset): Likewise. (union call_site_parameter_u): Rename "param_offset" field to "param_cu_off". * unittests/offset-type-selftests.c: New file.
2017-04-04 21:03:26 +02:00
/* 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_PREPROC_H
#define COMMON_PREPROC_H
/* Generally useful preprocessor bits. */
/* Concatenate two tokens. */
#define CONCAT_1(a, b) a ## b
#define CONCAT(a, b) CONCAT_1 (a, b)
/* Escape parens out. Useful if you need to pass an argument that
includes commas to another macro. */
#define ESC(...) __VA_ARGS__
#endif /* COMMON_PREPROC */