On Tuesday, 5 January 2021 02:53:54 -03 Tom Honermann via SG16 wrote:

 8. We *could* specify a new portable entry point (a new main()
    signature or an alternative to main()) that provides UTF-8 encoded
    command line arguments (presumably with substitution characters in
    place of non-transcodeable content).

Using an alternate entry point is already possible and resolves the command-
line problem: just use _wmain() and UTF-16.

Yes, but that is Windows specific.  What I had in mind was a new entry point that portably provides a UTF-8 encoded command line, perhaps simply:

int main(int argc, char8_t **argv) { ... }

Or perhaps with "raw" access to the command line in some way; perhaps similarly to std::filesystem::path:

namespace std {
  class argument {
    public:
      std::string_view   string()     const;
      std::wstring_view  wstring()    const;
      std::u8string_view u8string()   const;
      std::u16string_view u16string() const;
      std::u32string_view u32string() const;
  };
}

int main(std::initializer_list<std::argument> args) { ... }

(Arguments not withstanding regarding how to provide the argument range, avoid startup overhead, handle memory allocation, whether the command line should be accessible outside of main (e.g., __argv), whether the arguments should be mutable, whether the argument range should be a mutable container, which encodings to provide, what the return type of the converters should be, etc...)

The pipe problem is not local to 
the current process, but the *other* one, so it can't be fixed locally.

Indeed, a new entry point doesn't address this issue at all; I went on a tangent at the end there.  The point there was that we can assume the availability of a (possibly ill-formed) UTF-16 encoded command line on Windows and therefore provide an automatic non-lossy conversion to UTF-8 (or WTF-8).  And since Windows is (as far as I know) the only relevant OS that uses wide characters as its primary interface, such an entry point could be provided for all other implementations.

Tom.