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Merged
merged 5 commits into from
Jul 21, 2022
Merged

More systematic gcc & clang coverage #4083

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c994035
More systematic gcc coverage, based on https://github.com/pybind/pybi…
rwgk Jul 18, 2022
7d49b6c
Fix complete fail.
rwgk Jul 18, 2022
f633ed4
Resolve GCC 11 & 12 "redundant move in return statement" warnings.
rwgk Jul 19, 2022
da8168d
Also add clang 11, 12, 13 (to gather info for warning suppressions).
rwgk Jul 19, 2022
f6a3716
Add & use `PYBIND11_DETECTED_CLANG_WITH_MISLEADING_CALL_STD_MOVE_EXPL…
rwgk Jul 19, 2022
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20 changes: 13 additions & 7 deletions .github/workflows/ci.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -281,6 +281,12 @@ jobs:
std: 20
- clang: 10
std: 17
- clang: 11
std: 20
- clang: 12
std: 20
- clang: 13
std: 20
- clang: 14
std: 20

Expand Down Expand Up @@ -437,14 +443,14 @@ jobs:
strategy:
fail-fast: false
matrix:
gcc:
- 7
- latest
std:
- 11
include:
- gcc: 10
std: 20
- { gcc: 7, std: 11 }
- { gcc: 7, std: 17 }
- { gcc: 8, std: 14 }
- { gcc: 8, std: 17 }
- { gcc: 10, std: 17 }
- { gcc: 11, std: 20 }
- { gcc: 12, std: 20 }

name: "🐍 3 • GCC ${{ matrix.gcc }} • C++${{ matrix.std }}• x64"
container: "gcc:${{ matrix.gcc }}"
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18 changes: 18 additions & 0 deletions include/pybind11/detail/common.h
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Expand Up @@ -1158,6 +1158,24 @@ constexpr inline bool silence_msvc_c4127(bool cond) { return cond; }
# define PYBIND11_SILENCE_MSVC_C4127(...) __VA_ARGS__
#endif

#if defined(__clang__) \
&& (defined(__apple_build_version__) /* AppleClang 13.0.0.13000029 was the only data point \
available. */ \
|| (__clang_major__ >= 7 \
&& __clang_major__ <= 12) /* Clang 3, 5, 13, 14, 15 do not generate the warning. */ \
)
# define PYBIND11_DETECTED_CLANG_WITH_MISLEADING_CALL_STD_MOVE_EXPLICITLY_WARNING
// Example:
// tests/test_kwargs_and_defaults.cpp:46:68: error: local variable 'args' will be copied despite
// being returned by name [-Werror,-Wreturn-std-move]
// m.def("args_function", [](py::args args) -> py::tuple { return args; });
// ^~~~
// test_kwargs_and_defaults.cpp:46:68: note: call 'std::move' explicitly to avoid copying
// m.def("args_function", [](py::args args) -> py::tuple { return args; });
// ^~~~
// std::move(args)
#endif

// Pybind offers detailed error messages by default for all builts that are debug (through the
// negation of ndebug). This can also be manually enabled by users, for any builds, through
// defining PYBIND11_DETAILED_ERROR_MESSAGES.
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11 changes: 9 additions & 2 deletions include/pybind11/numpy.h
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Expand Up @@ -1865,9 +1865,13 @@ struct vectorize_helper {
}

auto result = returned_array::create(trivial, shape);
#ifdef PYBIND11_DETECTED_CLANG_WITH_MISLEADING_CALL_STD_MOVE_EXPLICITLY_WARNING
# pragma clang diagnostic push
# pragma clang diagnostic ignored "-Wreturn-std-move"
#endif

if (size == 0) {
return std::move(result);
return result;
}
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If you remove the std::move are the pragmas necessary here, anymore?

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Here a GCC 11 & 12 warning is at conflict with a clang 7 through 12 warning.

When GCC 11 & 12 complained, I simply removed the std::move. (Thinking: "Let's see what happens.")
Next CI: many clang failures.
Next CI: complete the clang coverage to better understand what is going on.

Looking at the results I concluded (guessed TBH): clang was wrong for a long time, but that was fixed in clang 13. The fix appears to stick: clang 14 & 15 agree.

Next CI: with pragmas for clang added.

I considered introducing something like

PYBIND11_SUPPRESS_MISLEADING_CLANG_WARNING_CALL_STD_MOVE_EXPLICITLY_BEGIN
...
PYBIND11_SUPPRESS_MISLEADING_CLANG_WARNING_CALL_STD_MOVE_EXPLICITLY_END

or

    return PYBIND11_KNOWN_REDUNDANT_STD_MOVE(result);

but decided against it because there are only two affected locations, and the implementation you see now is easier to understand just looking at the local code, without having to look elsewhere.


/* Call the function */
Expand All @@ -1878,7 +1882,10 @@ struct vectorize_helper {
apply_trivial(buffers, params, mutable_data, size, i_seq, vi_seq, bi_seq);
}

return std::move(result);
return result;
#ifdef PYBIND11_DETECTED_CLANG_WITH_MISLEADING_CALL_STD_MOVE_EXPLICITLY_WARNING
# pragma clang diagnostic pop
#endif
}

template <size_t... Index, size_t... VIndex, size_t... BIndex>
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11 changes: 10 additions & 1 deletion tests/test_kwargs_and_defaults.cpp
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Expand Up @@ -43,7 +43,16 @@ TEST_SUBMODULE(kwargs_and_defaults, m) {
m.def("kw_func_udl_z", kw_func, "x"_a, "y"_a = 0);

// test_args_and_kwargs
m.def("args_function", [](py::args args) -> py::tuple { return std::move(args); });
m.def("args_function", [](py::args args) -> py::tuple {
#ifdef PYBIND11_DETECTED_CLANG_WITH_MISLEADING_CALL_STD_MOVE_EXPLICITLY_WARNING
# pragma clang diagnostic push
# pragma clang diagnostic ignored "-Wreturn-std-move"
#endif
return args;
#ifdef PYBIND11_DETECTED_CLANG_WITH_MISLEADING_CALL_STD_MOVE_EXPLICITLY_WARNING
# pragma clang diagnostic pop
#endif
});
m.def("args_kwargs_function", [](const py::args &args, const py::kwargs &kwargs) {
return py::make_tuple(args, kwargs);
});
Expand Down