Champion "utf8 string literals"

[gafter]

• Proposal added
• Discussed in LDM
• Decision in LDM
• Finalized (done, rejected, inactive)
• Spec'ed

Proposal: https://github.com/dotnet/csharplang/blob/main/proposals/csharp-11.0/utf8-string-literals.md
Old draft proposal: #2911

Design Review

https://github.com/dotnet/csharplang/blob/main/meetings/2021/LDM-2021-10-27.md#utf-8-string-literals
https://github.com/dotnet/csharplang/blob/main/meetings/2022/LDM-2022-01-26.md#open-questions-in-utf-8-string-literals
https://github.com/dotnet/csharplang/blob/main/meetings/2022/LDM-2022-06-29.md#utf-8-literal-concatenation-operator

[MovGP0]

UTF-8 encodings come with a lot of issues for non-english languages and developers. So this feature might only be a good thing for english developers and a bad idea for everybody else.

It might be useful for interop with non-unicode applications, but then I prefer to have an explicit encoding conversation using System.Text.Encoding.

@MovGP0 I think this is related to https://github.com/dotnet/corefxlab/blob/master/docs/specs/parsing.md . UTF8 strings are very common and if you don't have to convert to UTF16 (== .NET strings) and back again you save memory and CPU.

[wanton7]

When UTF-8 string literals are added it would be nice to have UTF-8 version of StringBuilder as well.

[ufcpp]

@wanton7
This may be it:
https://github.com/dotnet/corefxlab/tree/master/src/System.Text.Formatting/System/Text/Formatting/Formatters

[sumtec]

I am quite curious about how it is going to handle the index operator.
utf8string utf8 = "©α中文𨙧: some regular Chinese and special characters “;
utf8char utf8c = utf8[5];

Does it mean the class need to enumerate and decode bytes to utf8characters inside until it finds the sixth character? Or, are you disallowing the index operator on the UTF8String?

Here are the similar questions:

• Will there be any function like Substring, Trim, EndsWith?
• Will there be any optimization when we have reversed looping, like this?
  for (var i= utf8.Length - 1; i>=0; i--) { /* do something */ }

If there no support or optimization for this, I would probably say probably we just need a syntax sugar for converting a string to a byte array with a UTF8 encoding.

[yaakov-h]

Those questions are better suited for corefx.

[miloush]

@sumtec and @MovGP0 .NET Micro Framework always had UTF-8 string implementation only, transparent to the developer. It does support trimming and substrings and indexing, although the reverse looping is not optimized (source). It saved memory. You could, however, have the same arguments around "normal" strings with surrogate pairs.