Make exec::without conditionally noexcept - #2213
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ericniebler
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Aug 17, 2026
| constexpr auto operator()(_Env&& __env, _Query) const noexcept | ||
| constexpr auto operator()(_Env&& __env, _Query) const noexcept( | ||
| STDEXEC::__nothrow_constructible_from< | ||
| STDEXEC::__if_c<STDEXEC::__queryable_with<_Env, _Query>, __without<_Env, _Query>, _Env>, |
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this isn't quite right because the function currently always returns by value, and _Env could be a reference type. Arguably, the function should either be returning a __without<_Env, _Query> or an _Env. it would probably be easiest to split this into two overloads instead of using an if constexpr.
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ericniebler
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Aug 18, 2026
Co-authored-by: Eric Niebler <eniebler@boost.org>
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/ok to test 1897253 |
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What changed
exec::withoutderive its exception specification from the selected return object construction.withoutonly stores a reference.Why
exec::withoutwas unconditionallynoexcept, even though it can move an rvalue environment into its return object. A throwing move could terminate instead of propagating the exception.Testing
build/test/exec/test.exec [env]ctest --test-dir build --output-on-failure -j 8All 953 configured tests passed.