On Wed, Aug 14, 2024 at 5:17 PM Tom Honermann via SG16 <
sg16_at_[hidden]> wrote:

> This is your friendly reminder that we are meeting *today*, in about 4
> hours.
>
> Tom.
> On 8/12/24 11:39 PM, Tom Honermann via SG16 wrote:
>
> SG16 will hold a meeting on Wednesday, August 14th, at 19:30 UTC (timezone
> conversion
> <https://www.timeanddate.com/worldclock/converter.html?iso=20240814T193000&p1=1440&p2=tz_pdt&p3=tz_mdt&p4=tz_cdt&p5=tz_edt&p6=tz_cest>
> ).
>
> The agenda follows.
>
> - D2996R5: Reflection for C++26 <https://wg21.link/d2996r5>.
> - P2319R0: Prevent path presentation problems
> <https://wg21.link/p2319r0>.
>
> We previously reviewed P2996R2 <https://wg21.link/p2996r2> during the
> 2024-04-24 <https://github.com/sg16-unicode/sg16-meetings#april-24th-2024>
> and 2024-05-08
> <https://github.com/sg16-unicode/sg16-meetings#may-8th-2024> SG16
> meetings. We also discussed some of the design options for reflecting names
> during the joint LEWG/SG16 review of P2996R4 <https://wg21.link/p2996r4>
> in St. Louis (see minutes here
> <https://wiki.edg.com/bin/view/Wg21stlouis2024/P2996#Library-Evolution-2024-06-26>;
> search for "SG16" or "Second Afternoon Session"), but did not finish
> discussion of all topics. The reflection authors have continued iterating
> on the design and a D2996R5 draft is available. There have been some
> notable changes that are relevant for SG16:
>
> 1. The name_of() and qualified_name_of() functions have been removed
> (along with their u8 prefixed variants).
> 2. The display_name_of() function has been renamed to
> display_string_of().
> 3. New identifier_of(), operator_of(), and define_static_string()
> functions have been added (along with u8 prefixed variants for
> identifier_of() and define_static_string()).
>
> The new identifier_of() function follows previously provided SG16
> guidance; invocations are not constant expressions if the identifier to be
> returned is not representable in the ordinary literal encoding (invocations
> of u8identifier_of() never fail to be constant expressions due to issues
> of representation).
>
> The new define_static_string() (and u8define_static_string()) functions
> have been added as a general interface to declare strings that will persist
> beyond a constant expression evaluation. These functions enable a string to
> be constructed during constant evaluation and then preserved for use as the
> backing storage of a std::string_view (or std::u8string_view) object at
> run-time.
>
>
There is no reason for define_static_string not to be an overloaded
function supporting both u8 and char strings.
u8 prefixes are only "necessary" for cases when the return type cannot be
deduced from the parameter.

As an aside, i would much rather make std::string allocation not transient
than introducing these ""hacks"" that are unlikely to be useful in the long
term


> I have asked Dan and Daveed to provide a brief introduction of the
> changes. We'll discuss the changes and potentially poll approval of these
> design aspects.
>
> P2319R0 is a new paper courtesy of Victor that seeks to resolve some
> ambiguous encoding issues with std::filesystem::path. It proposes to
> deprecate and replace the existing string() member function with new
> display_string() and system_string() member functions with clear encoding
> specifications. Similar replacements are proposed for the existing
> generic_string() member function. Note that these ambiguous encoding
> issues are not present for the u8, u16, and u32 prefixed variants of
> these functions; we can discuss whether similar concerns are present for
> wstring() and generic_wstring(). We'll review the paper and potentially
> poll forwarding it.
>
> Tom.
>
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