Buggy autocompletion for traits like std::ops::Add

[joseph-amirth]

rust-analyzer version: rust-analyzer version: 0.3.1756-standalone

rustc version: rustc 1.74.0 (79e9716c9 2023-11-13)

relevant settings:
I am using archlinux and I've installed the rust toolchain using the usual rustup default stable command. I haven't modified the rust installation in any way.

Expected Behavior
When "impl Add" is typed, "Add" should appear in the autocompletion list as it is an exact match.

Observed Behavior
Add is in the autocompletion list when I am still typing prefixes of Add ("A" and "Ad") but when I type the entire word "Add", Add mysteriously disappears from the autocompletion list.

The behavior is as expected for other traits like AddAssign (I get "AddAssign" in the autocompletion list even when I've typed the entire name out), but for traits like Add, Neg, Sub, Mul I get this buggy behavior where once the name is fully typed out, it disappears from the autocompletion list. The only pattern I've noticed is that these traits have 3 letters but I can't imagine such an arbitrary condition could cause this.

Minimal Reproducible Example:

1. Install VSCode and install the "rust-analyzer" plugin.

2. Create a new project and above the main function, type "impl Add" and observe that "Add" appears in the autocompletion list when only prefixes of Add ("A"/"Ad") have been typed, but "Add" disappears from the autocompletion list once the entire word is typed.

[Veykril]

3 is somewhat magical here as we do prefix matching for 1 and 2 characters but fuzzy matching for 3 and more, so what might be happening here is that these traits are kicked out of the completions because of the current number of completions limit imposed when fuzzy searching.

[joseph-amirth]

If you try this with Mul, you actually get only 4 results once you've typed out "Mul" (the results of course do not include "Mul" itself), while you get 12 results once you've typed out "Add". So this doesn't seem like an issue with the completion limit.

[Veykril]

#16107