Repository: rust
Issue: found unstable fingerprints for extern_mod_stmt_cnum
Labels: I-ICE,E-needs-test,T-compiler,A-incr-comp,C-bug,E-needs-mcve

I encountered this bug in the CI for my rcgen PR: https://github.com/est31/rcgen/pull/53

[full log link](https://github.com/est31/rcgen/commit/05e767ad713ebbbed1928c9361ce4d6bea183b54/checks/2107934871/logs)
```
Running `rustc --crate-name botan tests/botan.rs --error-format=json --json=diagnostic-rendered-ansi --emit=dep-info,link -C embed-bitcode=no -C debuginfo=2 --test --cfg 'feature="default"' --cfg 'feature="pem"' --cfg 'feature="x509-parser"' -C metadata=96712806c8dc92bf -C extra-filename=-96712806c8dc92bf --out-dir /Users/runner/work/rcgen/rcgen/target/debug/deps -C incremental=/Users/runner/work/rcgen/rcgen/target/debug/incremental -L dependency=/Users/runner/work/rcgen/rcgen/target/debug/deps --extern botan=/Users/runner/work/rcgen/rcgen/target/debug/deps/libbotan-0a4d2a3a26fb1b22.rlib --extern chrono=/Users/runner/work/rcgen/rcgen/target/debug/deps/libchrono-2edffe8c4cbe14a9.rlib --extern openssl=/Users/runner/work/rcgen/rcgen/target/debug/deps/libopenssl-921daadd081c933a.rlib --extern pem=/Users/runner/work/rcgen/rcgen/target/debug/deps/libpem-f00ebd26ddff9dd7.rlib --extern rcgen=/Users/runner/work/rcgen/rcgen/target/debug/deps/librcgen-bd616741af37ab36.rlib --extern ring=/Users/runner/work/rcgen/rcgen/target/debug/deps/libring-70ea1056c377f123.rlib --extern webpki=/Users/runner/work/rcgen/rcgen/target/debug/deps/libwebpki-9c88c2488ba93ec8.rlib --extern x509_parser=/Users/runner/work/rcgen/rcgen/target/debug/deps/libx509_parser-46230be220d16bf1.rlib --extern yasna=/Users/runner/work/rcgen/rcgen/target/debug/deps/libyasna-6f4481586b48639f.rlib -D warnings -L native=/Users/runner/work/rcgen/rcgen/target/debug/build/botan-sys-0bdd76b27e0e28d0/out/botan -L 'native=/usr/local/opt/openssl@1.1/lib' -L native=/Users/runner/work/rcgen/rcgen/target/debug/build/ring-7c4a53e107b77dd5/out`
thread 'rustc' panicked at 'found unstable fingerprints for extern_mod_stmt_cnum(rcgen[846b]::rcgen)', /rustc/acca818928654807ed3bc1ce0e97df118f8716c8/compiler/rustc_query_system/src/query/plumbing.rs:593:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.52.0-nightly (acca81892 2021-03-13) running on x86_64-apple-darwin

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type bin

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [extern_mod_stmt_cnum] computing crate imported by `rcgen`
#1 [check_mod_unstable_api_usage] checking for unstable API usage in top-level module
end of query stack
error: could not compile `rcgen`

Caused by:
  process didn't exit successfully: `rustc --crate-name rcgen src/main.rs --error-format=json --json=diagnostic-rendered-ansi --crate-type bin --emit=dep-info,link -C embed-bitcode=no -C debuginfo=2 --cfg 'feature="default"' --cfg 'feature="pem"' --cfg 'feature="x509-parser"' -C metadata=e67008cd305628cc --out-dir /Users/runner/work/rcgen/rcgen/target/debug/deps -C incremental=/Users/runner/work/rcgen/rcgen/target/debug/incremental -L dependency=/Users/runner/work/rcgen/rcgen/target/debug/deps --extern chrono=/Users/runner/work/rcgen/rcgen/target/debug/deps/libchrono-2edffe8c4cbe14a9.rlib --extern pem=/Users/runner/work/rcgen/rcgen/target/debug/deps/libpem-f00ebd26ddff9dd7.rlib --extern rcgen=/Users/runner/work/rcgen/rcgen/target/debug/deps/librcgen-bd616741af37ab36.rlib --extern ring=/Users/runner/work/rcgen/rcgen/target/debug/deps/libring-70ea1056c377f123.rlib --extern x509_parser=/Users/runner/work/rcgen/rcgen/target/debug/deps/libx509_parser-46230be220d16bf1.rlib --extern yasna=/Users/runner/work/rcgen/rcgen/target/debug/deps/libyasna-6f4481586b48639f.rlib -D warnings -L native=/Users/runner/work/rcgen/rcgen/target/debug/build/ring-7c4a53e107b77dd5/out` (exit code: 101)
warning: build failed, waiting for other jobs to finish...
```