refactor(toml): Decouple parsing from interning system

[epage]

What does this PR try to resolve?

To have a separate manifest API (#12801), we can't rely on interning because it might be used in longer-lifetime applications.

To keep this limited in scope, this only removes InternedString from manifest parsing. Everything else still uses InternedString.

How should we test and review this PR?

I had problems getting the cargo benchmarks running, so I did a quick and dirty benchmark that is end-to-end, covering fresh builds, clean builds, and resolution. I ran these against a fresh clone of cargo's code base. See my comment for the script that managed the benchmarks.

Benchmarks:

$ ../dump/cargo-12801-bench.rs run
    Finished dev [unoptimized + debuginfo] target(s) in 0.07s
     Running `target/debug/cargo -Zscript -Zmsrv-policy ../dump/cargo-12801-bench.rs run`
warning: `package.edition` is unspecified, defaulting to `2021`
    Finished dev [unoptimized + debuginfo] target(s) in 0.04s
     Running `/home/epage/.cargo/target/0a/7f4c1ab500f045/debug/cargo-12801-bench run`
$ hyperfine "../cargo-old check" "../cargo-new check"
Benchmark 1: ../cargo-old check
  Time (mean ± σ):     119.3 ms ±   3.2 ms    [User: 98.6 ms, System: 20.3 ms]
  Range (min … max):   115.6 ms … 124.3 ms    24 runs

Benchmark 2: ../cargo-new check
  Time (mean ± σ):     119.4 ms ±   2.4 ms    [User: 98.0 ms, System: 21.1 ms]
  Range (min … max):   115.7 ms … 123.6 ms    24 runs

Summary
  ../cargo-old check ran
    1.00 ± 0.03 times faster than ../cargo-new check
$ hyperfine --prepare "cargo clean" "../cargo-old check" "../cargo-new check"
Benchmark 1: ../cargo-old check
  Time (mean ± σ):     20.249 s ±  0.392 s    [User: 157.719 s, System: 22.771 s]
  Range (min … max):   19.605 s … 21.123 s    10 runs

Benchmark 2: ../cargo-new check
  Time (mean ± σ):     20.123 s ±  0.212 s    [User: 156.156 s, System: 22.325 s]
  Range (min … max):   19.764 s … 20.420 s    10 runs

Summary
  ../cargo-new check ran
    1.01 ± 0.02 times faster than ../cargo-old check
$ hyperfine --prepare "cargo clean && rm -f Cargo.lock" "../cargo-old check" "../cargo-new check"
Benchmark 1: ../cargo-old check
  Time (mean ± σ):     21.105 s ±  0.465 s    [User: 156.482 s, System: 22.799 s]
  Range (min … max):   20.156 s … 22.010 s    10 runs

Benchmark 2: ../cargo-new check
  Time (mean ± σ):     21.358 s ±  0.538 s    [User: 156.187 s, System: 22.979 s]
  Range (min … max):   20.703 s … 22.462 s    10 runs

Summary
  ../cargo-old check ran
    1.01 ± 0.03 times faster than ../cargo-new check

Additional information

I consulted https://github.com/rosetta-rs/string-rosetta-rs when deciding on what string type to use for performance.

Originally, I hoped to entirely replacing string interning. For that, I was looking at arcstr as it had a fast equality operator. However, that is only helpful so long as the two strings we are comparing came from the original source. Unsure how likely that is to happen (and daunted by converting all of the Copys into Clones), I decided to scale back.

Concerned about all of the small allocations when parsing a manifest, I assumed I'd need a string type with small-string optimizations, like hipstr, compact_str, flexstr, and ecow.
The first three give us more wiggle room and hipstr was the fastest of them, so I went with that.

I then double checked macro benchmarks, and realized hipstr made no difference and switched to String to keep things simple / with lower dependencies.

When doing this, I had created a type alias (TomlStr) for the string type so I could more easily swap it out if needed
(and not have to always write out a lifetime).
With just using String, I went ahead and dropped that.

[rustbot]

r? @ehuss

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[bors]

☔ The latest upstream changes (presumably #12884) made this pull request unmergeable. Please resolve the merge conflicts.

[ehuss]

Thanks!

@bors r+

[bors]

📌 Commit acc52f3 has been approved by ehuss

It is now in the queue for this repository.

[bors]

⌛ Testing commit acc52f3 with merge d1830f6...

[bors]

☀️ Test successful - checks-actions
Approved by: ehuss
Pushing d1830f6 to master...