clashing_extern_declarations: Use symbol interning to avoid string alloc.

[jumbatm]

Use symbol interning as a hack to avoid allocating a string for every symbol name we store in the seen set. This hopefully addresses the minor perf regression described in #80009 (comment).

r? @nagisa

[jumbatm]

Can I get a perf run on this? I'd like to verify that it actually makes an improvement.

[jonas-schievink]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

[bors]

⌛ Trying commit a1a7830 with merge e3e1e319c02abff43ec05f93be37b599825a5fd3...

[bors]

☀️ Try build successful - checks-actions
Build commit: e3e1e319c02abff43ec05f93be37b599825a5fd3 (e3e1e319c02abff43ec05f93be37b599825a5fd3)

[rust-timer]

Queued e3e1e319c02abff43ec05f93be37b599825a5fd3 with parent a2f8f62, future comparison URL.

@rustbot label: +S-waiting-on-perf

[rust-timer]

Finished benchmarking try commit (e3e1e319c02abff43ec05f93be37b599825a5fd3): comparison url.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. Please note that if the perf results are neutral, you should likely undo the rollup=never given below by specifying rollup- to bors.

Importantly, though, if the results of this run are non-neutral do not roll this PR up -- it will mask other regressions or improvements in the roll up.

@bors rollup=never
@rustbot label: +S-waiting-on-review -S-waiting-on-perf

[nagisa]

Doesn't look like this resolved the regression entirely, but there are minor improvements and Symbol > String here regardless

@bors r+

[bors]

📌 Commit a1a7830 has been approved by nagisa

[bors]

⌛ Testing commit a1a7830 with merge e7e07600fa1ea5bdcee187e76f235cc358b8d32f...

[rust-log-analyzer]

A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

Prepare workflow directory
Prepare all required actions
Getting action download info
Download action repository 'actions/checkout@v2'
##[warning]Failed to download action 'https://api.github.com/repos/actions/checkout/zipball/5a4ac9002d0be2fb38bd78e4b4dbde5606d7042f'. Error: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
##[warning]Back off 16.253 seconds before retry.
##[warning]Failed to download action 'https://api.github.com/repos/actions/checkout/zipball/5a4ac9002d0be2fb38bd78e4b4dbde5606d7042f'. Error: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
##[warning]Back off 16.681 seconds before retry.
##[error]A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.

[bors]

💔 Test failed - checks-actions

[nagisa]

@bors retry

[bors]

⌛ Testing commit a1a7830 with merge af5ad5e80928993b4196092db8a311091c3617cf...

[bors]

⌛ Testing commit a1a7830 with merge fd20a8b...

[rust-log-analyzer]

A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[bors]

☀️ Test successful - checks-actions
Approved by: nagisa
Pushing fd20a8b to master...