[WIP] Implement token-based handling of attributes

[Aaron1011]

Still needs some cleanup, opening for a preliminary perf run.

[rust-highfive]

r? @estebank

(rust-highfive has picked a reviewer for you, use r? to override)

[Aaron1011]

r? @ghost

[Aaron1011]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

[bors]

⌛ Trying commit 5e727f7b6211c00ff10c3e30fffd32c18256e968 with merge 5c23164c47aa9fef76aaf12c9208d3734277eedf...

[Aaron1011]

@bors try

[bors]

⌛ Trying commit 56295554ac24cd134a63951231028bd0e8392556 with merge d1b1f4501d48606232f1e44f2b76d126f68f3aea...

[Aaron1011]

@rust-timer queue

[rust-timer]

Awaiting bors try build completion.

[bors]

☀️ Try build successful - checks-actions
Build commit: d1b1f4501d48606232f1e44f2b76d126f68f3aea (d1b1f4501d48606232f1e44f2b76d126f68f3aea)

[rust-timer]

Queued d1b1f4501d48606232f1e44f2b76d126f68f3aea with parent ab5b9ae, future comparison URL.

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

[rust-timer]

Finished benchmarking try commit (d1b1f4501d48606232f1e44f2b76d126f68f3aea): 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

[Aaron1011]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

[bors]

⌛ Trying commit 7067bf03e7d3d17efa70f49ed7d4c49cc1690eb8 with merge e38d08da6180ca084747cc422341b0a81287b687...

[Aaron1011]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

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

[bors]

⌛ Trying commit 8b559123adb0a0bd2ca7125fa674c132d1792ba5 with merge c75d411ecc0bc7c763de15f780ea05da533c7e85...

[bors]

☀️ Try build successful - checks-actions
Build commit: c75d411ecc0bc7c763de15f780ea05da533c7e85 (c75d411ecc0bc7c763de15f780ea05da533c7e85)

[rust-timer]

Queued c75d411ecc0bc7c763de15f780ea05da533c7e85 with parent b02a619, future comparison URL.

[rust-timer]

Finished benchmarking try commit (c75d411ecc0bc7c763de15f780ea05da533c7e85): 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

[Aaron1011]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

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

[bors]

⌛ Trying commit 9264e1552a250cd4e6146510a1403755f6f36ffb with merge 661d708419d95b6566c3a05f8bae58bdc308672d...

[bors]

☀️ Try build successful - checks-actions
Build commit: 661d708419d95b6566c3a05f8bae58bdc308672d (661d708419d95b6566c3a05f8bae58bdc308672d)

[rust-timer]

Queued 661d708419d95b6566c3a05f8bae58bdc308672d with parent 446d453, future comparison URL.

[rust-timer]

Finished benchmarking try commit (661d708419d95b6566c3a05f8bae58bdc308672d): 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

[Aaron1011]

Blocked on #82448

[Aaron1011]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

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

[bors]

⌛ Trying commit aeaa8b1 with merge 023bf1c81e0066f88abc33b1d53bf5fdd7ebd78b...

[bors]

☀️ Try build successful - checks-actions
Build commit: 023bf1c81e0066f88abc33b1d53bf5fdd7ebd78b (023bf1c81e0066f88abc33b1d53bf5fdd7ebd78b)

[rust-timer]

Queued 023bf1c81e0066f88abc33b1d53bf5fdd7ebd78b with parent 8e863eb, future comparison URL.

[rust-timer]

Finished benchmarking try commit (023bf1c81e0066f88abc33b1d53bf5fdd7ebd78b): 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

[Aaron1011]

This thread has gotten enormous. Per @petrochenkov's suggestion, I've opened a new PR at #82608