Re: cc-mode fontification feels random

[Stefan Monnier]

>> I think that's where tree-sitter shines, because AFAIK it does not rely
>> on access to other files.
>
> I took a look at tree-sitter and, IIUC, it suffers from the same
> limitations as CC mode: it gets the information provided by a parser.

To a large extent that's unavoidable.  AFAIU it should be able to do
a slightly better job in some cases by just trying out all possible
interpretations and only keeping those that make sense (from a purely
syntactic point of view).

> But most fundamentally, it is unable to determine what
> Foo<whatever>::bar is even when it is defined on the current file.

Indeed it's quite possible that there are also cases where tree-sitter
does a worse job than CC-mode, e.g. by not taking into account semantic
information that can be extracted from the current file.

> If we are going to really modernize Emacs' programming language
> support we need to provide more than parser-based syntax highlighting
> and indentation. [...] That means we need something like LSP.

I believe/hope this is obvious to everyone, yes.

> Tree-sitter migth be useful for the languages not yet supported by
> LSP, though

My impression is that tree-sitter might be useful for
syntax-highlighting and indentation.  I'm not sure how well those two
features are supported/handled by LSP servers and clients currently.

> (but, if I got it right, tree-sitter is implemented on Javascript,

AFAIK only the source grammars and the grammar-compiler is written in
Javascript: the parsing engine is written in C and exposed as
a C library.

>> I think you'd expect a good LSP server to "degrade gracefully" and still
>> provide good info for indentation and syntax highlighting even if you
>> only have the one file and all the other files in the project
>> are missing.
> As already mentioned elsewhere on this thread, an LSP server with access
> to just the current file is severely handicapped.

Of course.  The question is whether it can still provide a good enough
behavior in that case compared to tree-sitter.  If not, it might be
an argument in favor of using both LSP and tree-sitter.


        Stefan