Drop noexcept specifier in defaulted Kokkos::complex default constructor
#4399
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core/src/Kokkos_Complex.hpp
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| @@ -77,7 +77,7 @@ class | |||
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| //! Default constructor (initializes both real and imaginary parts to zero). | |||
| KOKKOS_DEFAULTED_FUNCTION | |||
| complex() noexcept = default; | |||
| complex() KOKKOS_IMPL_IBM_WORKAROUND_NOEXCEPT_SPEC_CONSTRUCTOR = default; | |||
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No I think the right thing to do is just drop the noexcept
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For all toolchains?
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I agree with @dalg24 here.
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For all toolchains?
Yes. IMO, the noexcept should not have been there in the first place.
@nliber any opinion on this?
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What's the motivation for dropping noexcept? We have no failures outside the XL toolchains.
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The exception specification will be deduced by the compiler https://eel.is/c++draft/except.spec#7
and I can't think of a good reason why we would want to "force" the noexcept
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I agree we don't want to force the noexcept.
noexcept means that if an exception is in flight and it tries to get past that function call, std::terminate will be called. It means that an exception will not escape and not that an exception isn't thrown. In general, this can generate extra code.
As specified above, the defaulted special member functions just get it correct without having to specify it. There are standard library optimizations based on move and swap having the correct noexcept specification; anything else should have additional justification for adding it.
(The standard library adds noexcept to dereferencing smart pointers. The justification at the time was that is was never a pessimization and sometimes a performance improvement, but that claim was made w/o evidence.)
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While these don't necessarily pertain to our code, the current LEWG guidelines on noexcept in the standard library can be found in P0884. These rules are guidelines, but can be overridden as long as there is justification for doing so.
dalg24
changed the title
Kokkos::complex default constructor
Fixes #4376.
Tested d9187bb via nightly XL build number 51 and 9804013 via build number 52.