extend test for ICE when using #[no_mangle] on a generic item

[folkertdev]

The Instance::mono function panics when its input has generic parameters. The requires_monomorphization function detects exactly those cases.

The things you run into when messing with stdarch intrinsics and miri...

Here is the full ICE backtrace for posterity

Details

``` error: internal compiler error: /rustc-dev/942ac9ce4116d4ea784c9882659372b34978b1f8/compiler/rustc_middle/src/ty/instance.rs:466:17: Instance::mono: DefId(0:3 ~ exported_symbol_generic[a039]::generic_const) has const parameters

thread 'rustc' (51023) panicked at /rustc-dev/942ac9ce4116d4ea784c9882659372b34978b1f8/compiler/rustc_middle/src/ty/instance.rs:466:17:
Box
stack backtrace:
0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
1: <rustc_errors::diagnostic::BugAbort as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
2: rustc_middle::util::bug::opt_span_bug_fmt::<rustc_span::span_encoding::Span>::{closure#0}
3: rustc_middle::ty::context::tls::with_opt::<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}
4: rustc_middle::ty::context::tls::with_context_opt::<rustc_middle::ty::context::tls::with_opt<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
5: rustc_middle::util::bug::bug_fmt
6: <rustc_middle::ty::list::RawList<(), rustc_middle::ty::generic_args::GenericArg>>::fill_item::<<rustc_middle::ty::instance::Instance>::mono::{closure#0}>.llvm.2786884126274762998.cold
7: <rustc_middle::ty::instance::Instance>::mono
8: <rustc_const_eval::interpret::eval_context::InterpCxmiri::machine::MiriMachine as miri::shims::foreign_items::EvalContextExt>::lookup_exported_symbol::{closure#0}
at ./src/shims/foreign_items.rs:165:36
9: miri::helpers::iter_exported_symbols::<<rustc_const_eval::interpret::eval_context::InterpCxmiri::machine::MiriMachine as miri::shims::foreign_items::EvalContextExt>::lookup_exported_symbol::{closure#0}>
at ./src/helpers.rs:133:13
10: <rustc_const_eval::interpret::eval_context::InterpCxmiri::machine::MiriMachine as miri::shims::foreign_items::EvalContextExt>::lookup_exported_symbol
at ./src/shims/foreign_items.rs:147:17
11: miri::shims::sig::check_shim_symbol_clash
at ./src/shims/sig.rs:207:42
12: <rustc_const_eval::interpret::eval_context::InterpCxmiri::machine::MiriMachine as miri::shims::sig::EvalContextExt>::check_shim_sig_variadic_lenient::<2>
at ./src/shims/sig.rs:308:9
13: <rustc_const_eval::interpret::eval_context::InterpCxmiri::machine::MiriMachine as miri::shims::unix::foreign_items::EvalContextExt>::emulate_foreign_item_inner
at ./src/shims/unix/foreign_items.rs:316:26
14: <rustc_const_eval::interpret::eval_context::InterpCxmiri::machine::MiriMachine as miri::shims::foreign_items::EvalContextExtPriv>::emulate_foreign_item_inner
at ./src/shims/foreign_items.rs:886:25
15: <rustc_const_eval::interpret::eval_context::InterpCxmiri::machine::MiriMachine as miri::shims::foreign_items::EvalContextExt>::emulate_foreign_item
at ./src/shims/foreign_items.rs:76:20
16: <miri::machine::MiriMachine as rustc_const_eval::interpret::machine::Machine>::find_mir_or_eval_fn
at ./src/machine.rs:1267:24
17: <rustc_const_eval::interpret::eval_context::InterpCxmiri::machine::MiriMachine>::init_fn_call
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/rustc-src/rust/compiler/rustc_const_eval/src/interpret/call.rs:670:46
18: <rustc_const_eval::interpret::eval_context::InterpCxmiri::machine::MiriMachine>::eval_terminator
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/rustc-src/rust/compiler/rustc_const_eval/src/interpret/step.rs:559:22
19: <rustc_const_eval::interpret::eval_context::InterpCxmiri::machine::MiriMachine>::step
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/rustc-src/rust/compiler/rustc_const_eval/src/interpret/step.rs:67:14
20: <rustc_const_eval::interpret::eval_context::InterpCxmiri::machine::MiriMachine as miri::concurrency::thread::EvalContextExt>::miri_step
at ./src/concurrency/thread.rs:863:18
21: <rustc_const_eval::interpret::eval_context::InterpCxmiri::machine::MiriMachine as miri::concurrency::thread::EvalContextExt>::run_threads
at ./src/concurrency/thread.rs:1309:26
22: miri::eval::eval_entry::{closure#0}
at ./src/eval.rs:539:53
23: <miri::eval::eval_entry::{closure#0} as core::ops::function::FnOnce<()>>::call_once
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5
24: <core::panic::unwind_safe::AssertUnwindSafemiri::eval::eval_entry::{closure#0} as core::ops::function::FnOnce<()>>::call_once
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/src/rust/library/core/src/panic/unwind_safe.rs:275:9
25: std::panicking::catch_unwind::do_call::<core::panic::unwind_safe::AssertUnwindSafemiri::eval::eval_entry::{closure#0}, rustc_middle::mir::interpret::error::InterpResult<!>>
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/panicking.rs:575:43
26: std::panicking::catch_unwind::<rustc_middle::mir::interpret::error::InterpResult<!>, core::panic::unwind_safe::AssertUnwindSafemiri::eval::eval_entry::{closure#0}>
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/panicking.rs:543:19
27: std::panic::catch_unwind::<core::panic::unwind_safe::AssertUnwindSafemiri::eval::eval_entry::{closure#0}, rustc_middle::mir::interpret::error::InterpResult<!>>
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/panic.rs:359:14
28: miri::eval::eval_entry
at ./src/eval.rs:539:9
29: <miri::MiriCompilerCalls as rustc_driver_impl::Callbacks>::after_analysis
at ./src/bin/miri.rs:216:13
30: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
note: Some details are omitted, run with RUST_BACKTRACE=full for a verbose backtrace.

note: we would appreciate a bug report: https://github.com/rust-lang/miri/issues/new

note: please make sure that you have updated to the latest nightly

note: please attach the file at /home/folkertdev/rust/miri/rustc-ice-2026-06-28T10_34_34-51021.txt to your bug report

note: rustc 1.98.0-nightly (942ac9ce4 2026-06-22) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z ui-testing

query stack during panic:
end of query stack

Miri caused an ICE during evaluation. Here's the interpreter backtrace at the time of the panic:
note: the place in the program where the ICE was triggered
--> /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/sys/pal/unix/mod.rs:136:20
|
LL | if libc::fcntl(fd, libc::F_GETFD) == -1 && errno() == libc::EBADF {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: stack backtrace:
0: std::sys::pal::unix::init::sanitize_standard_fds
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/sys/pal/unix/mod.rs:136:20: 136:50
1: std::sys::pal::unix::init
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/sys/pal/unix/mod.rs:27:5: 27:28
2: std::rt::init
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/rt.rs:118:9: 118:39
3: std::rt::lang_start_internal::{closure#0}
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/rt.rs:173:18: 173:43
4: std::panicking::catch_unwind::do_call::<{closure@std::rt::lang_start_internal::{closure#0}}, isize>
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/panicking.rs:575:43: 575:46
5: std::panicking::catch_unwind::<isize, {closure@std::rt::lang_start_internal::{closure#0}}>
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/panicking.rs:543:19: 543:77
6: std::panic::catch_unwind::<{closure@std::rt::lang_start_internal::{closure#0}}, isize>
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/panic.rs:359:14: 359:40
7: std::rt::lang_start_internal
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/rt.rs:171:5: 193:7
8: std::rt::lang_start::<()>
at /home/folkertdev/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/rt.rs:205:5: 210:6

error: aborting due to 1 previous error

full stderr:
error: internal compiler error: /rustc-dev/942ac9ce4116d4ea784c9882659372b34978b1f8/compiler/rustc_middle/src/ty/instance.rs:466:17: Instance::mono: DefId(0:3 ~ exported_symbol_generic[a039]::generic_const) has const parameters

</details>

[RalfJung]

Isn't this already fixed by #5129?

[folkertdev]

oh, looks like it, but that hasn't made it to nightly yet. I have a bit more test coverage here (for const too).

[RalfJung]

Yeah the sync (rust-lang/rust#158501) landed after the most recent nightly came out.

[rustbot]

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.