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parallel compiler: static mut refs in lib not reproducible #162203
Description
followup #140413 :3
we still have problems with --crate-type lib
I tried this code:
#![crate_type="lib"]
static mut TEST: &'static mut [isize] = &mut [1];
static mut TEST_RAW: *mut [isize] = &mut [1isize] as *mut _;
pub fn main() {}rustc --edition=2024 -Zremap-cwd-prefix=reproducible_dir --cap-lints=warn -Ccodegen-units=1 -Clink-dead-code=true -Zthreads=30 -o out c.rs >& /dev/null ; md5sum out
I expected to see this happen: equal md5sums
Instead, this happened:flipflopping md5s
479f094c3654ecbd0f7fb298a98c12e6 out
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479f094c3654ecbd0f7fb298a98c12e6 out
479f094c3654ecbd0f7fb298a98c12e6 out
479f094c3654ecbd0f7fb298a98c12e6 out
479f094c3654ecbd0f7fb298a98c12e6 out
0e8d752e35f181aae67e3c4b925028bd out
479f094c3654ecbd0f7fb298a98c12e6 out
0e8d752e35f181aae67e3c4b925028bd out
479f094c3654ecbd0f7fb298a98c12e6 out
0e8d752e35f181aae67e3c4b925028bd out
0e8d752e35f181aae67e3c4b925028bd out
0e8d752e35f181aae67e3c4b925028bd out
479f094c3654ecbd0f7fb298a98c12e6 out
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0e8d752e35f181aae67e3c4b925028bd out
479f094c3654ecbd0f7fb298a98c12e6 out
Meta
rustc --version --verbose:
rustc 1.100.0-nightly (5db7f4be8 2026-09-01)
binary: rustc
commit-hash: 5db7f4be8a36c1b8ae19299469e2be2b0f052c21
commit-date: 2026-09-01
host: x86_64-unknown-linux-gnu
release: 1.100.0-nightly
LLVM version: 23.1.0
Activity
susitsm commentedon Sep 9, 2026
The cause is as described in #162202 (comment) . Static mut refs generate
DefId-s during const evel, inintern_as_new_static. When const eval is done in parallel, theseDefId's order won't be deterministic.