Some creates hang when building with opt-level=3

Hello,

Soru is using the crate async-stripe as a dependency in her project. For rustc, she is using 1.91.0-nightly. When compiling the crate async-stripe it seems to hang indefinitely, a single CPU pegged to 100%. Total waiting time tried out is over 14 hours.

Now, if soru overrides the opt-level for that single package to be 2

[profile.release.package.async-stripe]
opt-level = 2

the crate will indeed compile in a couple of minutes.

In 1.89.0-nightly this issue did not exist yet. No idea if it does in between, as soru never tried those.

Meta

rustc --version --verbose:

rustc 1.91.0-nightly (2e2642e64 2025-08-16)
binary: rustc
commit-hash: 2e2642e641a941f0a1400c7827fd89aa86fef8f4
commit-date: 2025-08-16
host: x86_64-unknown-linux-gnu
release: 1.91.0-nightly
LLVM version: 21.1.0

Start by reproducing the hang while compiling the async-stripe crate with rustc 1.91.0-nightly and opt-level=3, then compare it with opt-level=2 and 1.89.0-nightly. The payload names no Rust source files or tests; done means identifying the regression and adding an appropriate regression test or confirmed fix.