D Language Foundation April Quarterly Meeting and Server Meeting Summaries

[FeepingCreature]

On Wednesday, 4 May 2022 at 16:21:19 UTC, Mike Parker wrote:
> Mario also mentioned that Mathis Beer is having "the usual 
> problems" in his work because he is always "in the dark areas 
> of the D compiler", but they have nothing causing them any 
> major issues that need immediate attention.
>

I don't get sensible bugs anymore! It's all cryptic stuff like 
"if I use random feature one, then random feature two while 
wrapped in random feature three, plus a syntax error in an 
unrelated module, the compiler literally catches on fire."

My favorite recent one is 
https://issues.dlang.org/show_bug.cgi?id=22949

If you:

- define a module with an enum that has an initializer that 
doesn't exist
- and in another module, you define a struct
   - that speculatively compiles itself via `__traits(compiles)`
     - (dmd starts sweating nervously)
   - and imports from the first module a symbol that doesn't exist
   - then mixes it in
- then import the first module again
- and evaluate the enum

Then you get an "Error: Unknown."

This code has like three different errors! Missing import, mixin 
of a missing symbol, enum with an invalid initializer. Each of 
those individually, or in combinations of two, would be reported 
just fine. But, I think because `__traits(compiles)` 
strategically blocks *all* of them from being printed, the 
compiler ends up in a state where it knows that everything is 
wrong, but can no longer quite work out why or how.

They're all like this.

Well, that or bugs with `immutable`.