feat(linter): add read_to_arena_str function

[overlookmotel]

Alternative to #11816. Read a file from disk directly into an Allocator.

Unfortunately, involves a pretty egregious hack (see comments in code), but this appears to be the only way that stable Rust provides to read a file into uninitialized memory without UB. Bonkers!

[overlookmotel]

• feat(linter): read source text into the arena #11825
• feat(linter): add read_to_arena_str function #11823 👈 (View in Graphite)
• feat(allocator): add Allocator::alloc_slice_copy method #11822
• feat(allocator): add Allocator::alloc_layout method #11821
• main

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[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #11823 will improve performances by 15.08%

_{Comparing 06-19-feat_linter_add_read_to_arena_str_function (dc6f584) with main (f2ce5ad)}

Summary

⚡ 1 improvements
✅ 37 untouched benchmarks

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	mangler[cal.com.tsx]	3.5 ms	3.1 ms	+15.08%

[overlookmotel]

@camc314 I think this should work, but we'll need to check it doesn't regress performance before making a release that uses it.

There are issues in Rust repo about optimizations that make fs::read do less syscalls, and I'm not 100% sure whether this method will also get the benefit of those optimizations or not (or whether it makes any practical difference either way).

[camc314]

$ hyperfine --warmup 3 -n "main" '../../Boshen/oxc/target/release/oxlint --silent' -n "read str into allocator" '../../Boshen/oxc/target/release/str-into-alloc --silent'  -i
Benchmark 1: main
  Time (mean ± σ):     319.6 ms ±   2.3 ms    [User: 3132.9 ms, System: 185.8 ms]
  Range (min … max):   315.6 ms … 322.7 ms    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 2: read str into allocator
  Time (mean ± σ):     318.7 ms ±   3.3 ms    [User: 3126.3 ms, System: 181.0 ms]
  Range (min … max):   315.4 ms … 326.6 ms    10 runs

  Warning: Ignoring non-zero exit code.

Summary
  read str into allocator ran
    1.00 ± 0.01 times faster than main
$ hyperfine --warmup 3 -n "main" '../../Boshen/oxc/target/release/oxlint --silent' -n "read str into allocator" '../../Boshen/oxc/target/release/str-into-alloc --silent'  -i
Benchmark 1: main
  Time (mean ± σ):     322.2 ms ±   5.6 ms    [User: 3128.5 ms, System: 185.6 ms]
  Range (min … max):   316.0 ms … 332.7 ms    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 2: read str into allocator
  Time (mean ± σ):     323.3 ms ±   8.8 ms    [User: 3126.2 ms, System: 180.1 ms]
  Range (min … max):   315.3 ms … 336.4 ms    10 runs

  Warning: Ignoring non-zero exit code.

Summary
  main ran
    1.00 ± 0.03 times faster than read str into allocator

perf appears to be identical (or within noise limits)

( i benched this on my PR that's on top of this one so we're actually using this fn!)

[camc314]

Merge activity

• Jun 20, 9:03 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
• Jun 20, 9:03 AM UTC: camc314 added this pull request to the Graphite merge queue.
• Jun 20, 9:07 AM UTC: Merged by the Graphite merge queue.