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I believe it was discussed in Cologne, 'Enabling Constexpr Intrinsics......' - http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p166...

Quite a meaty document, should provide you with help for material on the subject.

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Even as a C++ amateur I didn't find it as a meaty or intimidating proposal, rather it was refreshingly brief. If you understand that constexpr functions can be evaluated at either run time or compile time, it makes sense that asm isn't allowed in a compile-time context (it could get really trippy if it was!). This allows for flow analysis to permit asm when evaluating at runtime within a constexpr function, as long as there's a non-asm constexpr alternative path available at compile time. If I'm misunderstanding or missing some subtleties, as a novice I'd appreciate any corrections.

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