[experiment] Eagerly expand cfg and cfg_attr in all attribute inputs

[petrochenkov]

Based on #84995.
r? @Aaron1011

[petrochenkov]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

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

[bors]

⌛ Trying commit a8c7b2a2d1480c233f0d66484d4a0ddc4354bde8 with merge b20a093d9fb1ffaa04ae9852cb034864a992bafd...

[bors]

☀️ Try build successful - checks-actions
Build commit: b20a093d9fb1ffaa04ae9852cb034864a992bafd (b20a093d9fb1ffaa04ae9852cb034864a992bafd)

[rust-timer]

Queued b20a093d9fb1ffaa04ae9852cb034864a992bafd with parent 50e1dc1, future comparison URL.

[petrochenkov]

@craterbot check

[craterbot]

👌 Experiment pr-85073 created and queued.
🤖 Automatically detected try build b20a093d9fb1ffaa04ae9852cb034864a992bafd
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[rust-timer]

Finished benchmarking try commit (b20a093d9fb1ffaa04ae9852cb034864a992bafd): 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

[craterbot]

🚧 Experiment pr-85073 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🎉 Experiment pr-85073 is completed!
📊 14 regressed and 12 fixed (161086 total)
📰 Open the full report.

⚠️ If you notice any spurious failure please add them to the blacklist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[petrochenkov]

Three root regressions:

• inkwell - the #[llvm_versions] macro legitimately processes #[cfg]s is its input.
• generic-tests - the #[generic_tests::define] macro legitimately processes #[cfg]s in its input.
• twilight-gateway - behavior of the redundant_semicolons lint is changed somehow.

[petrochenkov]

So, my conclusion is that it's a viable strategy, from both performance and compatibility point of view.