<numeric>: check for gcd / lcm overflows
#4776
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In compile time or in debug. Applies to C++20 and later mode.
`_Mul_overflow` is made to only handle non-`bool` integer types in C++17.
Backport overflow checking of `lcm`/`gcd` to C++17
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I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed. |
numeric: Add a `static_cast` when dividing `_Common_unsigned` by `_Common_unsigned`, due to the usual arithmetic conversions which will emit sign conversion warnings for tiny types. utility: * Move `_Is_standard_integer` down to the `_HAS_CXX20` region. (It's also used by `<mdspan>`.) * Relax the internal `_Cmp_equal`, `_Cmp_less`, and `_In_range` to accept nonbool integrals. + Because they're internal, we can `_STL_INTERNAL_STATIC_ASSERT`. + Comment that this "allows character types". * Enforce `_Is_standard_integer` at the user-visible layer. P0295R0_gcd_lcm: Add test coverage, because gcd/lcm are required to accept nonbool integrals. (An MSVC-internal test found this by using `char`.)
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I pushed a commit: Fix gcd/lcm to work with all nonbool integrals. numeric: Add a utility:
P0295R0_gcd_lcm: Add test coverage, because gcd/lcm are required to accept nonbool integrals. (An MSVC-internal test found this by using |
| @@ -883,38 +876,56 @@ _NODISCARD constexpr bool _In_range(const _Ty _Value) noexcept { | |||
| } | |||
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| #if _HAS_CXX20 | |||
| template <class _Ty> | |||
| constexpr bool _Is_standard_integer = _Is_any_of_v<remove_cv_t<_Ty>, signed char, short, int, long, long long, | |||
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Could be useful to comment that this can be used to test for standard and extended integer types, because there are no extended integer types (probably in a subsequent change)
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Thanks for implementing these checks! My internal branch was |
In compile time or in debug.
Fixes #2300