Finding all references to functions called new can take a long time

[umanwizard]

Sorry for the Materialize dependency, but I think a large-ish codebase is probably necessary to repro this.

To repro:

1. Check out https://github.com/MaterializeInc/materialize
2. Navigate over fn new in impl Locald (as of this writing, it's in src/expr/src/id.rs:45
3. Find all references
4. Observe it taking about 60s.

Maybe since finding references involves filtering by a string first, the very common name is what makes things slow? Just a guess.

[lnicola]

Confirmed:

   80 textDocument/references             36873ms

Seems to burn CPU in chalk for some reason. The second "find all references" (on GlobalId::is_system) takes 63ms, though. and a third one (on ResolvedRecordAccess::new) in 1ms.

[matklad]

Seems to burn CPU in chalk for some reason.

It basically type-checks the world (every function that has a new call) :D. To fix this, we need to double-check that we are using the correct scope here and don't, eg look in the stdlib. Then, we either need to come up with some sound optimization here (like looking for the struct at first), or to do something extra-clever and run the search on resolved code (which we might need for macros)... Let me draft an issue...

[jplatte]

Let me draft an issue...

Has this happened? I just came across how long it takes to find all references to a std item. Surely finding references in crates.io crates can be helpful and should probably have an option, but when do you actually want to find references in the standard library (except for the case of working on it)? 😅

[Veykril]

It has, I believe it's #7427

[alexkirsz]

We're frequently running into this in our codebase, which is about 230 crates large. Any method with a common-enough name like new or map will take in the dozens of seconds, sometimes minutes, to complete.

[Veykril]

This should have been hopefully improved by #17927