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### 3137. Header for `__cpp_lib_to_chars`

Section: 17.3.1 [support.limits.general] Status: C++20 Submitter: S. B.Tam Opened: 2018-07-03 Last modified: 2021-02-25

Priority: 0

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Discussion:

After acceptance of P0941R2 into the working draft, in [support.limits.general], `__cpp_lib_to_chars` is required to be in `<utility>`. Since the relevant feature (`std::to_chars` and `std::from_chars`) is now in the header `<charconv>`, should the macro be defined in `<charconv>` instead of `<utility>`?

[Marshall provides P/R and context]

`std::to_chars`, etc were originally proposed for the header `<utility>` and SD-6 reflected that. Somewhere along the way, they was put into their own header `<charconv>`, but the document was never updated to reflect that.

When these macros were added to the standard, the (now incorrect) value was copied as well.

[2018-07-20 Status to Tentatively Ready after five positive votes on the reflector.]

[2018-11, Adopted in San Diego]

Proposed resolution:

This wording is relative to (the Rapperswil post-mailing standard).

Change 17.3.1 [support.limits.general] (Table 35) as indicated:

Macro name | Value | Header(s)
--- | --- | ---
`__cpp_lib_to_chars` | `201611L` | `<charconvutility>`