On Mon, Oct 25, 2021 at 11:34:10PM +0000, Basile B. via Digitalmars-d wrote:
> On Sunday, 24 October 2021 at 20:04:05 UTC, Paul Backus wrote:
[...]
> > I have a shortcut set up in Vim that opens the [dpldocs.info][2] search page with the identifier under the cursor, which works pretty well for the standard library and ok for dub packages, but a language server could probably do a better job.
> > 
> > [2]: http://dpldocs.info/
> 
> I'm thinking to a new design lately.
> 
> The deamon would just keep the ast in sync and when a request is made the semantic is run from a particular point. The idea is that there's no need to run the sema for everything on each request.
> 
> We only need to have the AST up to date, undecorate it when a file changes, redecorate it when request are made. And important, only redecorate from what's asked.

The problem with this is that the current DMDFE mutates the AST as it goes along. So you either have to save a pristine copy of it somewhere in the server, somehow isolate and apply changes to it as you go along, and re-inject it into DMDFE (which according to Walter doesn't really improve performance that much), or you have to rewrite large swathes of the compiler to do its work without mutating the AST.


T

-- 
Never step over a puddle, always step around it. Chances are that whatever made it is still dripping.

On Mon, Oct 25, 2021 at 06:06:27PM +0000, Paul Backus via Digitalmars-d wrote:
> On Monday, 25 October 2021 at 17:45:22 UTC, H. S. Teoh wrote:
> > I suspect part of this problem is caused by the lame specialcased behaviour of template instantiation errors being ignored when it's opDispatch.  It's D's version of C++'s SFINAE, which leads to all sorts of stupidity like a typo inside opDispatch suddenly causing a dispatched member to disappear from existence 'cos the compiler swallows the error and pretends the member simply doesn't exist.  So if you're introspecting the member, the introspection code doesn't even see it.  Which leads to hours of head-scratching over "I obviously declared the darned member, why does the code NOT see it?!?!".
[...]
> It's actually worse than that. Errors inside `opDispatch` are gagged and cause member lookup to fail...*unless* they're nested inside *another* template, in which case member lookup will succeed, and you will only get the error when you try to actually access the member:
[...]
> It's special cases inside of special cases--a complete mess.

=-O

Wow, that's totally messed up. :-/  Yeah, if there's any way to fix this without breaking existing code, I'd love to push for this change in the language.  Not holding my breath for it, though, unfortunately.


T

-- 
Trying to define yourself is like trying to bite your own teeth. -- Alan Watts

On Tue, Oct 26, 2021 at 01:01:04AM +0000, Basile B. via Digitalmars-d wrote:
> On Monday, 25 October 2021 at 23:50:59 UTC, H. S. Teoh wrote:
> > On Mon, Oct 25, 2021 at 11:34:10PM +0000, Basile B. via Digitalmars-d wrote:
[...]
> > > We only need to have the AST up to date, undecorate it when a file changes, redecorate it when request are made. And important, only redecorate from what's asked.
> > 
> > The problem with this is that the current DMDFE mutates the AST as it goes along.
> 
> yeah indeed, aka lowerings...

But the thing is, lowerings don't *have* to be implemented as AST mutations. They can be a side-branch of the AST node for example. Or just translate to pure IR along with the rest of the code, then transformed as IR without touching the AST. It's more efficient (and less bug-prone) to transform IR than to meddle with the AST anyway.


T

-- 
Тише едешь, дальше будешь.