Incorrect highlighting for C++ special identifiers #8745

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1. chrisbra commented on Aug 30, 2021

   

   chrisbra

   on Aug 30, 2021

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   That is a CPP syntax issue. So I'll leave that for https://github.com/vim-jp/vim-cpp
2. chrisbra

   closed this as completedon Aug 30, 2021
3. dpelle commented on Aug 30, 2021

   

   dpelle

   on Aug 30, 2021

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   This is probably difficult to do properly as C++ syntax is complex and Vim does not use a C++ parser, but uses heuristics based on regexp for syntax highlighting. We can maybe improve heuristics, but we can't expect to get syntax highlighting it 100% right with heuristics. In practice, it's already doing a fairly good job for C++. Calling variables override,final or module seems quite rare and is asking for trouble. I understand that C++ allowed that for to avoid breaking existing software. Backward compatibility is important for C++. For Vim, the cost / benefit of fixing this ticket seems low IMO.

   The only way to syntax highlight C++ (and other languages) 100% correctly, is to have a real C++ parser using e.g. Tree-sitter. Maybe something for Vim-10? :-)
4. chrisbra commented on Aug 30, 2021

   

   chrisbra

   on Aug 30, 2021

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   yes, related: #8658

   Note, Vim cannot do semantic highlighting (yet), just regex based highlighting.
5. brammool commented on Aug 30, 2021

   

   brammool

   on Aug 30, 2021 via email

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   This is probably difficult to do properly as C++ syntax is complex and Vim does not use a C++ parser, but uses heuristics based on regexp for syntax highlighting. We can maybe improve heuristics, but we can't expect to get syntax highlighting it 100% right with heuristics. In practice, it's already doing a fairly good job for C++. Calling variables `override`,`final` or `module` seems quite a rare and is asking for trouble. I understand that C++ allowed that for to avoid breaking existing software. Backward compatibility is important for C++. For Vim, the cost / benefit of fixing this ticket seems low IMO. The only way to syntax highlight C++ correctly (and other languages) 100% correctly, is to have a real C++ parser using e.g. Tree-sitter. Maybe something for Vim-10? :-)

   I know someone was working on Tree-sitter, and it was not easy. Is it working now? Evaluating the advantages and disadvantages would be a good idea. I would expect it to behave very different from the pattern-based syntax highlighting. E.g., how well does it handle syntax errors? What happens while typing? Is there a noticeable delay when opening a large file? Does it solve the slowness of long lines (e.g. with XML)?

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6. chrisbra commented on Aug 30, 2021

   

   chrisbra

   on Aug 30, 2021

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   apparently it works quite nicely for Neovim (for languages that have treesitter parsers).