1.95 beta regression: stack overflow inside parser

[theemathas]

Regression found by the 1.95 beta crater run.

[INFO] [stderr] error: rustc interrupted by SIGSEGV, printing backtrace
[INFO] [stderr] 
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.95.0-beta.3-x86_64-unknown-linux-gnu/lib/librustc_driver-c1a4ee0be8fb5b4c.so(+0x3b6096c)[0x7aeebb56096c]
[INFO] [stderr] /lib/x86_64-linux-gnu/libc.so.6(+0x45330)[0x7aeeb7833330]
[INFO] [stderr] /lib/x86_64-linux-gnu/libc.so.6(pthread_mutex_trylock+0xc)[0x7aeeb788eefc]
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.95.0-beta.3-x86_64-unknown-linux-gnu/bin/rustc(+0x24d7f)[0x6307552fbd7f]
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.95.0-beta.3-x86_64-unknown-linux-gnu/bin/rustc(+0x14b54)[0x6307552ebb54]
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.95.0-beta.3-x86_64-unknown-linux-gnu/lib/librustc_driver-c1a4ee0be8fb5b4c.so(+0x5480d10)[0x7aeebce80d10]
[INFO] [stderr] 
[INFO] [stderr] ### cycle encountered after 6 frames with period 10
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.95.0-beta.3-x86_64-unknown-linux-gnu/lib/librustc_driver-c1a4ee0be8fb5b4c.so(_RNvMNtNtCs1gAZ6foNq5q_11rustc_parse6parser4exprNtB4_6Parser21parse_expr_assoc_with+0x45)[0x7aeebce79d85]
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.95.0-beta.3-x86_64-unknown-linux-gnu/lib/librustc_driver-c1a4ee0be8fb5b4c.so(+0x54261b0)[0x7aeebce261b0]
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.95.0-beta.3-x86_64-unknown-linux-gnu/lib/librustc_driver-c1a4ee0be8fb5b4c.so(_RNvMNtNtCs1gAZ6foNq5q_11rustc_parse6parser4stmtNtB4_6Parser27parse_stmt_without_recovery+0xd46)[0x7aeebce3ac5e]
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.95.0-beta.3-x86_64-unknown-linux-gnu/lib/librustc_driver-c1a4ee0be8fb5b4c.so(+0x5442772)[0x7aeebce42772]
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.95.0-beta.3-x86_64-unknown-linux-gnu/lib/librustc_driver-c1a4ee0be8fb5b4c.so(+0x5481149)[0x7aeebce81149]
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.95.0-beta.3-x86_64-unknown-linux-gnu/lib/librustc_driver-c1a4ee0be8fb5b4c.so(_RNvMNtNtCs1gAZ6foNq5q_11rustc_parse6parser4exprNtB4_6Parser21parse_expr_assoc_with+0x45)[0x7aeebce79d85]
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.95.0-beta.3-x86_64-unknown-linux-gnu/lib/librustc_driver-c1a4ee0be8fb5b4c.so(+0x54261b0)[0x7aeebce261b0]
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.95.0-beta.3-x86_64-unknown-linux-gnu/lib/librustc_driver-c1a4ee0be8fb5b4c.so(_RNvMNtNtCs1gAZ6foNq5q_11rustc_parse6parser4stmtNtB4_6Parser27parse_stmt_without_recovery+0xd46)[0x7aeebce3ac5e]
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.95.0-beta.3-x86_64-unknown-linux-gnu/lib/librustc_driver-c1a4ee0be8fb5b4c.so(+0x5442772)[0x7aeebce42772]
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.95.0-beta.3-x86_64-unknown-linux-gnu/lib/librustc_driver-c1a4ee0be8fb5b4c.so(+0x5481149)[0x7aeebce81149]
[INFO] [stderr] ### recursed 25 times
[INFO] [stderr] 
[INFO] [stderr] 
[INFO] [stderr] note: rustc unexpectedly overflowed its stack! this is a bug
[INFO] [stderr] note: maximum backtrace depth reached, frames may have been lost
[INFO] [stderr] note: we would appreciate a report at https://github.com/rust-lang/rust
[INFO] [stderr] help: you can increase rustc's stack size by setting RUST_MIN_STACK=16777216
[INFO] [stderr] note: backtrace dumped due to SIGSEGV! resuming signal
[INFO] [stderr] error: could not compile `rmk-types` (lib)

https://crater-reports.s3.amazonaws.com/beta-1.95-3/1.95.0-beta.3/reg/rmk-types-0.2.2/log.txt

[jieyouxu]

This one I suspect is probably a case of just-over-recursion-threshold

[theemathas]

Notably, zenpzero on the community discord has previously reported seeing a similar crash on stable rust with a small program on the playground. Nobody else was able to reproduce the crash. We were guessing that it was probably a playground cacheing thing.