Re: cc-mode fontification feels random

[Óscar Fuentes]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>> not everything is laid out 100% yet.  The user will expect that some
>> completion cases could be inaccurate when not everything is coded yet,
>> but the user will NOT expect to see inaccurate "syntax highlighting"
>> or indentation, nor incorrect "show definition" and "show callers"
>> results for the code that was already written, and in particular for
>> the code in the file being edited.
>
> 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.

For starts, in C++, being limited to the current file means that it is
unable to determine if Foo::bar is a type, a value or a function when
Foo is defined on a header file.

But most fundamentally, it is unable to determine what
Foo<whatever>::bar is even when it is defined on 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. We need smart code completion, code hints, transformations,
etc. That means we need something like LSP. Tree-sitter migth be useful
for the languages not yet supported by LSP, though (but, if I got it
right, tree-sitter is implemented on Javascript, so it requires a JS
engine to work, maybe too much of a dependency for something that
doesn't add that much over what we have now.)

> 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. One thing is to miss
the information about some functions yet-to-be-written and another thing
entirely is to ignore everything not defined on the current file.