cplusplus / cplusplus/draft

[stdfloat.syn] Which part is implementation-defined? CWG3036

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Description

It seems that the synopsis indicates unnecessary uncertainty. E.g., whenever std::float16_t is supported, we can always declare typedef-name as using float16_t = decltype(0.0f16);.

It doesn't make much sense to document the exact spelling used by the implementation, on which the difference is unobservable. And it should be possible to replace the implementation-defined parts with certain decltype-specifiers (namely decltype(0.0f16), decltype(0.0f32), decltype(0.0f64), decltype(0.0f128), and decltype(0.0bf16) or somthing like).

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Research direction

Start with the stdfloat.syn synopsis and read the CWG3036 context to identify which wording is implementation-defined. Compare the listed floating-point typedefs with the proposed decltype forms, then determine the precise synopsis update and confirm that the specification no longer documents unobservable spelling differences.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
compilers
Issue type
Documentation
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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