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| author | Pedro Alves <pedro@palves.net> | 2022-07-19 00:26:33 +0100 |
|---|---|---|
| committer | Pedro Alves <pedro@palves.net> | 2022-07-25 16:04:05 +0100 |
| commit | 4ca26ad7dec88ab6fa8507ba069e9f1b3c5196da (patch) | |
| tree | fa700e4b28e26409d03dac0dc187f73565f00c55 /gdbsupport | |
| parent | f7f904e4fda6fb571d40a3547ed03ec6028e6694 (diff) | |
| download | binutils-gdb-4ca26ad7dec88ab6fa8507ba069e9f1b3c5196da.tar.gz | |
struct packed: Use gcc_struct on Windows
Building GDB on mingw/gcc hosts is currently broken, due to a static
assertion failure in gdbsupport/packed.h:
In file included from ../../../../../binutils-gdb/gdb/../gdbsupport/common-defs.h:201,
from ../../../../../binutils-gdb/gdb/defs.h:28,
from ../../../../../binutils-gdb/gdb/dwarf2/read.c:31:
../../../../../binutils-gdb/gdb/../gdbsupport/packed.h: In instantiation of 'packed<T, Bytes>::packed(T) [with T = dwarf_unit_type; long long unsigned int Bytes = 1]':
../../../../../binutils-gdb/gdb/dwarf2/read.h:181:74: required from here
../../../../../binutils-gdb/gdb/../gdbsupport/packed.h:41:40: error: static assertion failed
41 | gdb_static_assert (sizeof (packed) == Bytes);
| ~~~~~~~~~~~~~~~~^~~~~~~~
../../../../../binutils-gdb/gdb/../gdbsupport/gdb_assert.h:27:48: note: in definition of macro 'gdb_static_assert'
27 | #define gdb_static_assert(expr) static_assert (expr, "")
| ^~~~
../../../../../binutils-gdb/gdb/../gdbsupport/packed.h:41:40: note: the comparison reduces to '(4 == 1)'
41 | gdb_static_assert (sizeof (packed) == Bytes);
| ~~~~~~~~~~~~~~~~^~~~~~~~
The issue is that mingw gcc defaults to "-mms-bitfields", which
affects how bitfields are laid out. We can however tell GCC that we
want the regular GCC layout instead using attribute gcc_struct.
Attribute gcc_struct is not implemented in "clang -target
x86_64-pc-windows-gnu", so that will need a different fix.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29373
Change-Id: I023315ee03622c59c397bf4affc0b68179c32374
Diffstat (limited to 'gdbsupport')
| -rw-r--r-- | gdbsupport/packed.h | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/gdbsupport/packed.h b/gdbsupport/packed.h index 3468cf44207..53164a9e0c3 100644 --- a/gdbsupport/packed.h +++ b/gdbsupport/packed.h @@ -27,8 +27,16 @@ bit-fields (and ENUM_BITFIELD), when the fields must have separate memory locations to avoid data races. */ +/* We need gcc_struct on Windows GCC, as otherwise the size of e.g., + "packed<int, 1>" will be larger than what we want. */ +#if defined _WIN32 +# define ATTRIBUTE_GCC_STRUCT __attribute__((__gcc_struct__)) +#else +# define ATTRIBUTE_GCC_STRUCT +#endif + template<typename T, size_t Bytes = sizeof (T)> -struct packed +struct ATTRIBUTE_GCC_STRUCT packed { public: packed () noexcept = default; |