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ae61525fcf
When building with clang 16, we get:
CXX gdb.o
In file included from /home/smarchi/src/binutils-gdb/gdb/gdb.c:19:
In file included from /home/smarchi/src/binutils-gdb/gdb/defs.h:65:
/home/smarchi/src/binutils-gdb/gdb/../gdbsupport/enum-flags.h:95:52: error: integer value -1 is outside the valid range of values [0, 15] for this enumeration type [-Wenum-constexpr-conversion]
integer_for_size<sizeof (T), static_cast<bool>(T (-1) < T (0))>::type
^
The error message does not make it clear in the context of which enum
flag this fails (i.e. what is T in this context), but it doesn't really
matter, we have similar warning/errors for many of them, if we let the
build go through.
clang is right that the value -1 is invalid for the enum type we cast -1
to. However, we do need this expression in order to select an integer
type with the appropriate signedness. That is, with the same signedness
as the underlying type of the enum.
I first wondered if that was really needed, if we couldn't use
std::underlying_type for that. It turns out that the comment just above
says:
/* Note that std::underlying_type<enum_type> is not what we want here,
since that returns unsigned int even when the enum decays to signed
int. */
I was surprised, because std::is_signed<std::underlying_type<enum_type>>
returns the right thing. So I tried replacing all this with
std::underlying_type, see if that would work. Doing so causes some
build failures in unittests/enum-flags-selftests.c:
CXX unittests/enum-flags-selftests.o
/home/smarchi/src/binutils-gdb/gdb/unittests/enum-flags-selftests.c:254:1: error: static assertion failed due to requirement 'gdb::is_same<selftests::enum_flags_tests::check_valid_expr254::archetype<enum_flags<s
elftests::enum_flags_tests::RE>, selftests::enum_flags_tests::RE, enum_flags<selftests::enum_flags_tests::RE2>, selftests::enum_flags_tests::RE2, enum_flags<selftests::enum_flags_tests::URE>, selftests::enum_fla
gs_tests::URE, int>, selftests::enum_flags_tests::check_valid_expr254::archetype<enum_flags<selftests::enum_flags_tests::RE>, selftests::enum_flags_tests::RE, enum_flags<selftests::enum_flags_tests::RE2>, selfte
sts::enum_flags_tests::RE2, enum_flags<selftests::enum_flags_tests::URE>, selftests::enum_flags_tests::URE, unsigned int>>::value == true':
CHECK_VALID (true, int, true ? EF () : EF2 ())
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/smarchi/src/binutils-gdb/gdb/unittests/enum-flags-selftests.c:91:3: note: expanded from macro 'CHECK_VALID'
CHECK_VALID_EXPR_6 (EF, RE, EF2, RE2, UEF, URE, VALID, EXPR_TYPE, EXPR)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/smarchi/src/binutils-gdb/gdb/../gdbsupport/valid-expr.h:105:3: note: expanded from macro 'CHECK_VALID_EXPR_6'
CHECK_VALID_EXPR_INT (ESC_PARENS (typename T1, typename T2, \
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/smarchi/src/binutils-gdb/gdb/../gdbsupport/valid-expr.h:66:3: note: expanded from macro 'CHECK_VALID_EXPR_INT'
static_assert (gdb::is_detected_exact<archetype<TYPES, EXPR_TYPE>, \
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This is a bit hard to decode, but basically enumerations have the
following funny property that they decay into a signed int, even if
their implicit underlying type is unsigned. This code:
enum A {};
enum B {};
int main() {
std::cout << std::is_signed<std::underlying_type<A>::type>::value
<< std::endl;
std::cout << std::is_signed<std::underlying_type<B>::type>::value
<< std::endl;
auto result = true ? A() : B();
std::cout << std::is_signed<decltype(result)>::value << std::endl;
}
produces:
0
0
1
So, the "CHECK_VALID" above checks that this property works for enum flags the
same way as it would if you were using their underlying enum types. And
somehow, changing integer_for_size to use std::underlying_type breaks that.
Since the current code does what we want, and I don't see any way of doing it
differently, ignore -Wenum-constexpr-conversion around it.
Change-Id: Ibc82ae7bbdb812102ae3f1dd099fc859dc6f3cc2
168 lines
5.2 KiB
C
168 lines
5.2 KiB
C
/* Copyright (C) 2017-2023 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef DIAGNOSTICS_H
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#define DIAGNOSTICS_H
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/* If at all possible, fix the source rather than using these macros
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to silence warnings. If you do use these macros be aware that
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you'll need to condition their use on particular compiler versions,
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which can be done for gcc using ansidecl.h's GCC_VERSION macro.
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gcc versions between 4.2 and 4.6 do not allow pragma control of
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diagnostics inside functions, giving a hard error if you try to use
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the finer control available with later versions.
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gcc prior to 4.2 warns about diagnostic push and pop.
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The other macros have restrictions too, for example gcc-5, gcc-6
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and gcc-7 warn that -Wstringop-truncation is unknown, unless you
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also add DIAGNOSTIC_IGNORE ("-Wpragma"). */
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#ifdef __GNUC__
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# define DIAGNOSTIC_PUSH _Pragma ("GCC diagnostic push")
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# define DIAGNOSTIC_POP _Pragma ("GCC diagnostic pop")
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/* Stringification. */
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# define DIAGNOSTIC_STRINGIFY_1(x) #x
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# define DIAGNOSTIC_STRINGIFY(x) DIAGNOSTIC_STRINGIFY_1 (x)
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# define DIAGNOSTIC_IGNORE(option) \
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_Pragma (DIAGNOSTIC_STRINGIFY (GCC diagnostic ignored option))
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# define DIAGNOSTIC_ERROR(option) \
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_Pragma (DIAGNOSTIC_STRINGIFY (GCC diagnostic error option))
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#else
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# define DIAGNOSTIC_PUSH
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# define DIAGNOSTIC_POP
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# define DIAGNOSTIC_IGNORE(option)
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#endif
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#if defined (__clang__) /* clang */
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# define DIAGNOSTIC_IGNORE_SELF_MOVE DIAGNOSTIC_IGNORE ("-Wself-move")
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# define DIAGNOSTIC_IGNORE_DEPRECATED_DECLARATIONS \
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DIAGNOSTIC_IGNORE ("-Wdeprecated-declarations")
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# define DIAGNOSTIC_IGNORE_DEPRECATED_REGISTER \
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DIAGNOSTIC_IGNORE ("-Wdeprecated-register")
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# if __has_warning ("-Wenum-compare-switch")
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# define DIAGNOSTIC_IGNORE_SWITCH_DIFFERENT_ENUM_TYPES \
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DIAGNOSTIC_IGNORE ("-Wenum-compare-switch")
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# endif
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# define DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL \
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DIAGNOSTIC_IGNORE ("-Wformat-nonliteral")
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# if __has_warning ("-Wuser-defined-warnings")
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# define DIAGNOSTIC_IGNORE_USER_DEFINED_WARNINGS \
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DIAGNOSTIC_IGNORE ("-Wuser-defined-warnings")
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# endif
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# if __has_warning ("-Wunused-but-set-variable")
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# define DIAGNOSTIC_IGNORE_UNUSED_BUT_SET_VARIABLE \
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DIAGNOSTIC_IGNORE ("-Wunused-but-set-variable")
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# endif
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# define DIAGNOSTIC_ERROR_SWITCH \
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DIAGNOSTIC_ERROR ("-Wswitch")
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# if __has_warning ("-Wenum-constexpr-conversion")
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# define DIAGNOSTIC_IGNORE_ENUM_CONSTEXPR_CONVERSION \
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DIAGNOSTIC_IGNORE ("-Wenum-constexpr-conversion")
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# endif
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#elif defined (__GNUC__) /* GCC */
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# define DIAGNOSTIC_IGNORE_DEPRECATED_DECLARATIONS \
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DIAGNOSTIC_IGNORE ("-Wdeprecated-declarations")
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# if __GNUC__ >= 7
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# define DIAGNOSTIC_IGNORE_DEPRECATED_REGISTER \
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DIAGNOSTIC_IGNORE ("-Wregister")
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# endif
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# define DIAGNOSTIC_IGNORE_STRINGOP_TRUNCATION \
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DIAGNOSTIC_IGNORE ("-Wstringop-truncation")
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# if __GNUC__ >= 11
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# define DIAGNOSTIC_IGNORE_STRINGOP_OVERREAD \
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DIAGNOSTIC_IGNORE ("-Wstringop-overread")
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#endif
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# define DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL \
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DIAGNOSTIC_IGNORE ("-Wformat-nonliteral")
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# if __GNUC__ >= 5
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# define DIAGNOSTIC_IGNORE_UNUSED_BUT_SET_VARIABLE \
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DIAGNOSTIC_IGNORE ("-Wunused-but-set-variable")
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# endif
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# if __GNUC__ >= 13
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# define DIAGNOSTIC_IGNORE_SELF_MOVE DIAGNOSTIC_IGNORE ("-Wself-move")
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# endif
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/* GCC 4.8's "diagnostic push/pop" seems broken when using this, -Wswitch
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remains enabled at the error level even after a pop. Therefore, don't
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use it for GCC < 5. */
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# if __GNUC__ >= 5
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# define DIAGNOSTIC_ERROR_SWITCH DIAGNOSTIC_ERROR ("-Wswitch")
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# endif
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#endif
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#ifndef DIAGNOSTIC_IGNORE_SELF_MOVE
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# define DIAGNOSTIC_IGNORE_SELF_MOVE
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#endif
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#ifndef DIAGNOSTIC_IGNORE_DEPRECATED_DECLARATIONS
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# define DIAGNOSTIC_IGNORE_DEPRECATED_DECLARATIONS
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#endif
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#ifndef DIAGNOSTIC_IGNORE_DEPRECATED_REGISTER
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# define DIAGNOSTIC_IGNORE_DEPRECATED_REGISTER
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#endif
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#ifndef DIAGNOSTIC_IGNORE_SWITCH_DIFFERENT_ENUM_TYPES
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# define DIAGNOSTIC_IGNORE_SWITCH_DIFFERENT_ENUM_TYPES
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#endif
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#ifndef DIAGNOSTIC_IGNORE_STRINGOP_TRUNCATION
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# define DIAGNOSTIC_IGNORE_STRINGOP_TRUNCATION
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#endif
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#ifndef DIAGNOSTIC_IGNORE_STRINGOP_OVERREAD
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# define DIAGNOSTIC_IGNORE_STRINGOP_OVERREAD
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#endif
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#ifndef DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL
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# define DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL
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#endif
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#ifndef DIAGNOSTIC_IGNORE_USER_DEFINED_WARNINGS
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# define DIAGNOSTIC_IGNORE_USER_DEFINED_WARNINGS
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#endif
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#ifndef DIAGNOSTIC_IGNORE_UNUSED_BUT_SET_VARIABLE
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# define DIAGNOSTIC_IGNORE_UNUSED_BUT_SET_VARIABLE
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#endif
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#ifndef DIAGNOSTIC_ERROR_SWITCH
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# define DIAGNOSTIC_ERROR_SWITCH
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#endif
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#ifndef DIAGNOSTIC_IGNORE_ENUM_CONSTEXPR_CONVERSION
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# define DIAGNOSTIC_IGNORE_ENUM_CONSTEXPR_CONVERSION
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#endif
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#endif /* DIAGNOSTICS_H */
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