[ICE]: regression causes stackoverflow/SIGSEGV in test on s390x

Analysis

After #160535 we saw a regression in tests/ui/match/match-stack-overflow-72933-.rs on s390x targets. It seems that the default stack-size of 16MB is not enough for this test on s390x.

This highlights actually multiple problems:

• the default stack size of 16MB on s390x is not enough. -> I will create a PR and set it so the test wont fail any more.
• IMHO RUST_MIN_STACK is misleading. This variable actually fixes the stack size to at least this value but will not allow growth beyond (as there is no RUST_MAX_STACK i understood its meaning very fast).
• increasing the stack size with ulimit -s did not help. this was surprising, but i guess it makes sense that the compiler will not take such value from the OS but rely on proven good defaults.

Links

• #160535
• #160275
• rust-lang/compiler-team#1011

Code

https://github.com/rust-lang/rust/blob/26747db4f50d83f3670834410ac16fbd39c14c15/tests/ui/match/match-stack-overflow-72933-.rs#L1-L5209

Meta

rustc --version --verbose:

current HEAD

rustc 1.97.0-nightly (66da6cae1 2026-04-20)
binary: rustc
commit-hash: 66da6cae1a6f12e9585493ab8f8f19cf753091fd
commit-date: 2026-04-20
host: s390x-unknown-linux-gnu
release: 1.97.0-nightly
LLVM version: 22.1.2

Error output

Building test helpers for s390x-unknown-linux-gnu
Testing stage1 with compiletest suite=ui mode=ui (s390x-unknown-linux-gnu)

running 1 tests

[ui] tests/ui/match/match-stack-overflow-72933-.rs ... F


failures:

---- [ui] tests/ui/match/match-stack-overflow-72933-.rs stdout ----

error: test compilation failed although it shouldn't!
status: signal: 11 (SIGSEGV) (core dumped)
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/home3/eddy/src/rust/build/s390x-unknown-linux-gnu/stage1/bin/rustc" "/home3/eddy/src/rust/tests/ui/match/match-stack-overflow-72933-.rs" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore
-directory-in-diagnostics-source-blocks=/home/eddy/.cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/home3/eddy/src/rust/vendor" "--sysroot" "/home3/eddy/src/rust/build/s390x-unknown-linux-gnu/stage1" "--target=s390x-unknown-linux-gnu" "--check-cfg" "cfg(test,FALSE)" "--error-format" "json" "--json" "future-
incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "-C" "prefer-dynamic" "--out-dir" "/home3/eddy/src/rust/build/s390x-unknown-linux-gnu/test/ui/match/match-stack-overflow-72933-" "-Znext-solver=coherence" "-A" "unused" "-W" "unused_attributes
" "-A" "internal_features" "-A" "incomplete_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "-Lnative=/home3/eddy/src/rust/build/s390x-unknown-linux-gnu/native/rust-test-helpers"
stdout: none
--- stderr -------------------------------
error: rustc interrupted by SIGSEGV, printing backtrace

/home3/eddy/src/rust/build/s390x-unknown-linux-gnu/stage1/lib/librustc_driver-bf213c6416d65d01.so(+0xee4fee) [0x3ffaa3e4fee]
linux-vdso.so.1(__kernel_sigreturn+0x0) [0x3ffca6fe4d8]
/home3/eddy/src/rust/build/s390x-unknown-linux-gnu/stage1/lib/librustc_driver-bf213c6416d65d01.so(+0x65018ee) [0x3ffafa018ee]
/home3/eddy/src/rust/build/s390x-unknown-linux-gnu/stage1/lib/librustc_driver-bf213c6416d65d01.so(+0x651dec0) [0x3ffafa1dec0]

### cycle encountered after 4 frames with period 5
/home3/eddy/src/rust/build/s390x-unknown-linux-gnu/stage1/lib/librustc_driver-bf213c6416d65d01.so(+0x651db80) [0x3ffafa1db80]
/home3/eddy/src/rust/build/s390x-unknown-linux-gnu/stage1/lib/librustc_driver-bf213c6416d65d01.so(+0x644030e) [0x3ffaf94030e]
/home3/eddy/src/rust/build/s390x-unknown-linux-gnu/stage1/lib/librustc_driver-bf213c6416d65d01.so(+0x657775c) [0x3ffafa7775c]
/home3/eddy/src/rust/build/s390x-unknown-linux-gnu/stage1/lib/librustc_driver-bf213c6416d65d01.so(+0x651a948) [0x3ffafa1a948]
/home3/eddy/src/rust/build/s390x-unknown-linux-gnu/stage1/lib/librustc_driver-bf213c6416d65d01.so(+0x651de6e) [0x3ffafa1de6e]
### recursed 50 times

/home3/eddy/src/rust/build/s390x-unknown-linux-gnu/stage1/lib/librustc_driver-bf213c6416d65d01.so(+0x651db80) [0x3ffafa1db80]
/home3/eddy/src/rust/build/s390x-unknown-linux-gnu/stage1/lib/librustc_driver-bf213c6416d65d01.so(+0x644030e) [0x3ffaf94030e]

note: rustc unexpectedly overflowed its stack! this is a bug
note: maximum backtrace depth reached, frames may have been lost
note: we would appreciate a report at https://github.com/rust-lang/rust
help: you can increase rustc's stack size by setting RUST_MIN_STACK=33554432
------------------------------------------

---- [ui] tests/ui/match/match-stack-overflow-72933-.rs stdout end ----

failures:
    [ui] tests/ui/match/match-stack-overflow-72933-.rs

test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 22106 filtered out; finished in 1.54s

Some tests failed in compiletest suite=ui mode=ui host=s390x-unknown-linux-gnu target=s390x-unknown-linux-gnu
Build completed unsuccessfully in 0:00:02

Start by reproducing tests/ui/match/match-stack-overflow-72933-.rs on the s390x target and read the linked issues #160535 and #160275 for the regression context. Inspect where the s390x compiler test stack size is configured; done means this test compiles successfully on s390x without SIGSEGV while preserving behavior on other targets.