Download beta compiler toolchain in bootstrap if it doesn't yet exist

[onur-ozkan]

Blocker for #107812 and #99989

See: #107812 (comment)

r? @jyn514

[jyn514]

Feels a little not in the spirit of things for me to review my own commit 😆

r? bootstrap

[Mark-Simulacrum]

@rustbot author

[onur-ozkan]

@bors r=Mark-Simulacrum rollup

[bors]

📌 Commit 6f8e470 has been approved by Mark-Simulacrum

It is now in the queue for this repository.

[ehuss]

@bors r-

Failed in rollup: #109872 (comment)

[onur-ozkan]

We are having problem at https://github.com/ozkanonur/rust/blob/6f8e47092cfbfbc944db848928bc92ca982041ea/src/bootstrap/download.rs#L421-L423 due to race condition on Windows platform.

I don't really want to add another dependency for Windows in bootstrap:( What if we don't remove the bin_root and leave it as it is, can't overriding files and dirs work here? @jyn514

for extra information, see:

• https://rust-lang.zulipchat.com/#narrow/stream/122651-general/topic/When.20can.20.60remove_dir_all.60.20fail.20on.20Windows.3F/near/250010930
• fs::remove_dir_all rarely succeeds for large directories on windows #29497

[ChrisDenton]

I'm not sure that adding another dependency would help. This looks like a more fundamental issue. A process in the directory is still running (maybe bootstrap itself?) and this will prevent deletion.

[onur-ozkan]

Oh, I thought completely different stuff.

By roughly looking on the changes, the problem is seems like we are trying to remove stage0 while using it.

[onur-ozkan]

@bors r=Mark-Simulacrum rollup=iffy

[bors]

📌 Commit eeec732 has been approved by Mark-Simulacrum

It is now in the queue for this repository.

[bors]

⌛ Testing commit eeec732 with merge ba86600...

[bors]

☀️ Test successful - checks-actions
Approved by: Mark-Simulacrum
Pushing ba86600 to master...

[rust-timer]

Finished benchmarking commit (ba86600): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	3.0%	[3.0%, 3.0%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Cycles

This benchmark run did not return any relevant results for this metric.