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author | Laurent Pinchart <laurent.pinchart@ideasonboard.com> | 2023-05-01 05:57:11 +0300 |
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committer | Kieran Bingham <kieran.bingham@ideasonboard.com> | 2023-05-01 11:17:36 +0100 |
commit | af7d6a4c2df6c836ecc704ea44b39ea07418d832 (patch) | |
tree | 21c24709f04e6879909cafb5b3a0fc8f368185d1 /utils/ipc/mojo/public/tools/bindings/gen_data_files_list.py | |
parent | 36435e2aeac66dcba3255c62622154579cc38cd4 (diff) |
meson: Ignore -Wredundant-move with gcc-13 and newer
Starting from 13.1, gcc implements the C++23 version of automatic move
from local variables in return statements (see
https://en.cppreference.com/w/cpp/language/return). As a result, some
previously required explicit `std::move()` in return statements generate
warnings. This is the case when a function returns an object whose type
is a class derived from the class type the function returns:
struct U { };
struct T : U { };
U f()
{
T t;
return t;
}
Up to C++20, the automatic move from local variables selects the move
constructor of class U, which is not the move constructor of the
expression. Overload resolution is then performed a second time, with t
considered as an lvalue. An explicit `std::move(t)` is needed in the
return statement to select the U move constructor.
Starting from C++23, `t` is treated as an xvalue, and the U move
constructor is selected without the need for an explicit `std::move(t)`.
An explicit `std:move()` then generates a redundant-move warning, as in
the valueOrTuple() function in src/py/libcamera/py_helpers.cpp.
Omitting the `std::move()` silences the warning, but selects the copy
constructor of U with older gcc versions and with clang, which
negatively impacts performance.
The easiest fix is to disable the warning. With -Wpessimizing-move
enabled, the compiler will still warn of pessimizing moves, only the
redundant but not pessimizing moves will be ignored.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Diffstat (limited to 'utils/ipc/mojo/public/tools/bindings/gen_data_files_list.py')
0 files changed, 0 insertions, 0 deletions