[WIP] Investigate mark_used(attr)

[petrochenkov]

r? @ghost

[petrochenkov]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion

[bors]

⌛ Trying commit 5a7416d56af30cb913f0efcfc4fe7a8c950e934c with merge e1489337a11ba38720eba65fe1dd549de224ab40...

[bors]

☀️ Try build successful - checks-actions, checks-azure
Build commit: e1489337a11ba38720eba65fe1dd549de224ab40 (e1489337a11ba38720eba65fe1dd549de224ab40)

[rust-timer]

Queued e1489337a11ba38720eba65fe1dd549de224ab40 with parent 6b09c37, future comparison URL.

[rust-timer]

Finished benchmarking try commit (e1489337a11ba38720eba65fe1dd549de224ab40): 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

[petrochenkov]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion

[bors]

⌛ Trying commit ecf5823911045b2beff2ea829d070fcfb205b734 with merge b514752e6643f54cbcf1fc1685e0fe4c4e6e3c4d...

[bors]

☀️ Try build successful - checks-actions, checks-azure
Build commit: b514752e6643f54cbcf1fc1685e0fe4c4e6e3c4d (b514752e6643f54cbcf1fc1685e0fe4c4e6e3c4d)

[rust-timer]

Queued b514752e6643f54cbcf1fc1685e0fe4c4e6e3c4d with parent b5eae9c, future comparison URL.

[rust-timer]

Finished benchmarking try commit (b514752e6643f54cbcf1fc1685e0fe4c4e6e3c4d): 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