Use match instead of phf for confusable lookup (#5953)

I don't know whether we want to make this change but here's some data...

Binary size:

- `main`: 30,384
- `charlie/match-phf`: 30,416

llvm-lines:

- `main`: 1,784,148
- `charlie/match-phf`: 1,789,877

llvm-lines and binary size are both unchanged (or, by < 5) when moving
from `u8` to `u32` return types, and even when moving to `char` keys and
values. I didn't expect this, but I'm not very knowledgable on this
topic.

Performance:

```
Confusables/match/src   time:   [4.9102 µs 4.9352 µs 4.9777 µs]
                        change: [+1.7469% +2.2421% +2.8710%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 12 outliers among 100 measurements (12.00%)
  2 (2.00%) low mild
  4 (4.00%) high mild
  6 (6.00%) high severe
Confusables/match-with-skip/src
                        time:   [2.0676 µs 2.0945 µs 2.1317 µs]
                        change: [+0.9384% +1.6000% +2.3920%] (p = 0.00 < 0.05)
                        Change within noise threshold.
Found 8 outliers among 100 measurements (8.00%)
  3 (3.00%) high mild
  5 (5.00%) high severe
Confusables/phf/src     time:   [31.087 µs 31.188 µs 31.305 µs]
                        change: [+1.9262% +2.2188% +2.5496%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 15 outliers among 100 measurements (15.00%)
  3 (3.00%) low mild
  6 (6.00%) high mild
  6 (6.00%) high severe
Confusables/phf-with-skip/src
                        time:   [2.0470 µs 2.0486 µs 2.0502 µs]
                        change: [-0.3093% -0.1446% +0.0106%] (p = 0.08 > 0.05)
                        No change in performance detected.
Found 4 outliers among 100 measurements (4.00%)
  2 (2.00%) high mild
  2 (2.00%) high severe
```

The `-with-skip` variants add our optimization which first checks
whether the character is ASCII. So `match` is way, way faster than PHF,
but it tends not to matter since almost all source code is ASCII anyway.

Cargo.lock

@@ -1524,7 +1524,6 @@ version = "0.11.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ade2d8b8f33c7333b51bcf0428d37e217e9f32192ae4772156f65063b8ce03dc"
 dependencies = [
- "phf_macros",
  "phf_shared",
 ]
 
@@ -1548,19 +1547,6 @@ dependencies = [
  "rand",
 ]
 
-[[package]]
-name = "phf_macros"
-version = "0.11.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3444646e286606587e49f3bcf1679b8cef1dc2c5ecc29ddacaffc305180d464b"
-dependencies = [
- "phf_generator",
- "phf_shared",
- "proc-macro2",
- "quote",
- "syn 2.0.23",
-]
-
 [[package]]
 name = "phf_shared"
 version = "0.11.2"
@@ -1916,7 +1902,6 @@ dependencies = [
  "path-absolutize",
  "pathdiff",
  "pep440_rs",
- "phf",
  "pretty_assertions",
  "pyproject-toml",
  "quick-junit",

crates/ruff/Cargo.toml

@@ -55,7 +55,6 @@ path-absolutize = { workspace = true, features = [
 ] }
 pathdiff = { version = "0.2.1" }
 pep440_rs = { version = "0.3.1", features = ["serde"] }
-phf = { version = "0.11", features = ["macros"] }
 pyproject-toml = { version = "0.6.0" }
 quick-junit = { version = "0.3.2" }
 regex = { workspace = true }

crates/ruff/src/rules/ruff/rules/ambiguous_unicode_character.rs

@@ -7,7 +7,7 @@ use ruff_macros::{derive_message_formats, violation};
 use ruff_python_ast::source_code::Locator;
 
 use crate::registry::AsRule;
-use crate::rules::ruff::rules::confusables::CONFUSABLES;
+use crate::rules::ruff::rules::confusables::confusable;
 use crate::rules::ruff::rules::Context;
 use crate::settings::Settings;
 
@@ -193,7 +193,7 @@ pub(crate) fn ambiguous_unicode_character(
             // Check if the boundary character is itself an ambiguous unicode character, in which
             // case, it's always included as a diagnostic.
             if !current_char.is_ascii() {
-                if let Some(representant) = CONFUSABLES.get(&(current_char as u32)).copied() {
+                if let Some(representant) = confusable(current_char as u32) {
                     let candidate = Candidate::new(
                         TextSize::try_from(relative_offset).unwrap() + range.start(),
                         current_char,
@@ -207,7 +207,7 @@ pub(crate) fn ambiguous_unicode_character(
         } else if current_char.is_ascii() {
             // The current word contains at least one ASCII character.
             word_flags |= WordFlags::ASCII;
-        } else if let Some(representant) = CONFUSABLES.get(&(current_char as u32)).copied() {
+        } else if let Some(representant) = confusable(current_char as u32) {
             // The current word contains an ambiguous unicode character.
             word_candidates.push(Candidate::new(
                 TextSize::try_from(relative_offset).unwrap() + range.start(),

scripts/update_ambiguous_characters.py

@@ -9,16 +9,16 @@ CONFUSABLES_RS_PATH = "crates/ruff/src/rules/ruff/rules/confusables.rs"
 AMBIGUOUS_JSON_URL = "https://raw.githubusercontent.com/hediet/vscode-unicode-data/main/out/ambiguous.json"
 
 prelude = """
-/// This file is auto-generated by `scripts/update_ambiguous_characters.py`.
-use phf::phf_map;
+//! This file is auto-generated by `scripts/update_ambiguous_characters.py`.
 
 /// Via: <https://github.com/hediet/vscode-unicode-data/blob/main/out/ambiguous.json>
 /// See: <https://github.com/microsoft/vscode/blob/095ddabc52b82498ee7f718a34f9dd11d59099a8/src/vs/base/common/strings.ts#L1094>
-#[allow(clippy::unreadable_literal)]
-pub(crate) static CONFUSABLES: phf::Map<u32, u8> = phf_map! {
+pub(crate) fn confusable(c: u32) -> Option<u8> {
+  let result = match c {
+
 """.lstrip()
 
-postlude = """};"""
+postlude = """_ => return None, }; Some(result)}"""
 
 
 def get_mapping_data() -> dict: