-Wbraced-scalar-init warns inappropriately #54702
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clang:diagnostics
New/improved warning or error message in Clang, but not in clang-tidy or static analyzer
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EugeneZelenko
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clang:diagnostics
hsutter
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to hsutter/cppfront
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this issue
Apr 1, 2023
Note this change adds `{` `}` around member assignment statements in assignment operators.
That change now triggers Clang's `-Wbraced-scalar-init` warning, but this warning appears to be spurious. See the open Clang issue here llvm/llvm-project#54702 which mentions the same justification I had in mind (disallow implicit narrowing, that's the #1 reason to recommend using `{` `}` init where possible). Unfortunately that Clang issue still open without comments after a year and so it's hard to know the status.
(BTW, what a coincidence -- I actually hit this on the exact first anniversary of that issue, which also happens to be April 1 but I swear this is not a joke and I think the LLVM issue wasn't either...)
vLKp
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to dxx-rebirth/dxx-rebirth
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this issue
Nov 13, 2023
As reported in <llvm/llvm-project#54702>, clang warns about use of braces in contexts where they are useful to explicitly disallow narrowing conversions. Such braces should not be removed, as it would allow a future change to accidentally introduce a narrowing conversion and not receive a diagnostic. As of this commit, the LLVM issue has seen no activity and there is no indication the spurious warning will be fixed. Add an SConf test to detect if the compiler warns for these cases, and suppress it if so.
zaucy
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to zaucy/cppfront
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this issue
Dec 5, 2023
Note this change adds `{` `}` around member assignment statements in assignment operators.
That change now triggers Clang's `-Wbraced-scalar-init` warning, but this warning appears to be spurious. See the open Clang issue here llvm/llvm-project#54702 which mentions the same justification I had in mind (disallow implicit narrowing, that's the hsutter#1 reason to recommend using `{` `}` init where possible). Unfortunately that Clang issue still open without comments after a year and so it's hard to know the status.
(BTW, what a coincidence -- I actually hit this on the exact first anniversary of that issue, which also happens to be April 1 but I swear this is not a joke and I think the LLVM issue wasn't either...)
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Braces around the returned value serve a legitimate purpose in
They tell the compiler to fail because the return value is narrowed; without the braces this would compile. Yet,
-Wbraced-scalar-initwarns that this is a superfluous use of braces. Likewise if the type ofiis insteadcharthe braces legitimately ask the compiler to check for narrowing, which in this case is not occurring; in this situation too,-Wbraced-scalar-initshould not be warning that this is a superfluous use of braces. (In practical cases, the returned value might be from a function that has a return type that is not so readily apparent and the code writer should instead be encouraged to use braces in situations where narrowing is a concern!)This occurs with both:
and:
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