delay a bug when encountering an ambiguity in MIR typeck

[aliemjay]

We shouldn't have any trait selection ambiguities in MIR typeck.

See #114586 (comment)

r? @oli-obk @compiler-errors @lcnr

[compiler-errors]

Makes sense.

r? compiler-errors @bors r+

[bors]

📌 Commit 710c073 has been approved by compiler-errors

It is now in the queue for this repository.

[bors]

⌛ Testing commit 710c073 with merge 20b9ec8...

[lcnr]

what kinds of programs ICE if you change tis to a bug! instead?

[rust-log-analyzer]

The job x86_64-apple-2 failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

---- [ui] tests/ui/panics/default-backtrace-ice.rs stdout ----
diff of stderr:

7 
8 aborting due to `-Z treat-err-as-bug=1`
- (end_short_backtrace)
11 (begin_short_backtrace)
12 (end_short_backtrace)
13 (begin_short_backtrace)
---
To only update this specific test, also pass `--test-args panics/default-backtrace-ice.rs`

error: 1 errors occurred comparing output.
status: exit status: 101
command: env -u RUST_BACKTRACE RUSTC_ICE="0" "/Users/runner/work/rust/rust/build/x86_64-apple-darwin/stage2/bin/rustc" "/Users/runner/work/rust/rust/tests/ui/panics/default-backtrace-ice.rs" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/Users/runner/.cargo" "--sysroot" "/Users/runner/work/rust/rust/build/x86_64-apple-darwin/stage2" "--target=x86_64-apple-darwin" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/Users/runner/work/rust/rust/build/x86_64-apple-darwin/test/ui/panics/default-backtrace-ice" "-A" "unused" "-A" "internal_features" "-Crpath" "-Cdebuginfo=0" "-Lnative=/Users/runner/work/rust/rust/build/x86_64-apple-darwin/native/rust-test-helpers" "-L" "/Users/runner/work/rust/rust/build/x86_64-apple-darwin/test/ui/panics/default-backtrace-ice/auxiliary" "-Z" "treat-err-as-bug=1"
--- stderr -------------------------------
error[E0425]: cannot find value `missing_ident` in this scope
##[error]  --> /Users/runner/work/rust/rust/tests/ui/panics/default-backtrace-ice.rs:21:13
   |
   |
LL | fn main() { missing_ident; }

thread 'rustc' panicked at compiler/rustc_errors/src/lib.rs:1729:30:
thread 'rustc' panicked at compiler/rustc_errors/src/lib.rs:1729:30:
aborting due to `-Z treat-err-as-bug=1`
   0:        0x1031fc80b - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hab9a645d4c6cae58
   1:        0x10325ced3 - core::fmt::write::h255af4a54bb1fa79
   2:        0x1031f1b2e - std::io::Write::write_fmt::he05f6325a196c841
   3:        0x1031fc5e9 - std::sys_common::backtrace::print::he315a4faa7beea82
   3:        0x1031fc5e9 - std::sys_common::backtrace::print::he315a4faa7beea82
   4:        0x1031ff9e5 - std::panicking::default_hook::{{closure}}::ha06ef57fa3fc186f
   5:        0x1031ff74c - std::panicking::default_hook::h6a7faad2270d4b15
   6:        0x10bbb3eac - std[671f820cec1cf149]::panicking::update_hook::<alloc[74d386d8e8450bf7]::boxed::Box<rustc_driver_impl[8cf711d4d0fcadf9]::install_ice_hook::{closure#0}>>::{closure#0}
   8:        0x1031ffe27 - std::panicking::begin_panic_handler::{{closure}}::ha83980314bc0c146
   9:        0x1031fcd19 - ___udivmoddi4
  10:        0x1031ffb9d - _rust_begin_unwind
  11:        0x103288215 - core::panicking::panic_fmt::h9e138a7655e4026a
  11:        0x103288215 - core::panicking::panic_fmt::h9e138a7655e4026a
  12:        0x1106b573f - <rustc_errors[4a2f97d5a6758d7a]::HandlerInner>::panic_if_treat_err_as_bug
  13:        0x1106b4a87 - <rustc_errors[4a2f97d5a6758d7a]::HandlerInner>::emit_diagnostic::{closure#2}
  14:        0x10bd1e95f - rustc_interface[35dd32b46cf34317]::callbacks::track_diagnostic
  15:        0x1106b43ee - <rustc_errors[4a2f97d5a6758d7a]::HandlerInner>::emit_diagnostic
  16:        0x1106d8101 - <rustc_span[68ec3145a42ee6ed]::ErrorGuaranteed as rustc_errors[4a2f97d5a6758d7a]::diagnostic_builder::EmissionGuarantee>::diagnostic_builder_emit_producing_guarantee
  17:        0x10f04011d - <rustc_resolve[9ee15daa354b9ce8]::Resolver>::report_errors
  18:        0x10f0be093 - <rustc_session[15201c05148c3e3]::session::Session>::time::<(), <rustc_resolve[9ee15daa354b9ce8]::Resolver>::resolve_crate::{closure#0}>
  19:        0x10f0736fe - <rustc_resolve[9ee15daa354b9ce8]::Resolver>::resolve_crate
  20:        0x10bd25475 - rustc_interface[35dd32b46cf34317]::passes::resolver_for_lowering
  21:        0x10f6c394d - rustc_query_impl[fe09369826c2ba2]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[fe09369826c2ba2]::query_impl::resolver_for_lowering::dynamic_query::{closure#2}::{closure#0}, rustc_middle[f2b601c0ba6c1077]::query::erase::Erased<[u8; 8usize]>>
  22:        0x10f7f8179 - <rustc_query_impl[fe09369826c2ba2]::query_impl::resolver_for_lowering::dynamic_query::{closure#2} as core[30426629a36827b9]::ops::function::FnOnce<(rustc_middle[f2b601c0ba6c1077]::ty::context::TyCtxt, ())>>::call_once
  23:        0x10f615f1b - rustc_query_system[f56bcbed907ebf29]::query::plumbing::try_execute_query::<rustc_query_impl[fe09369826c2ba2]::DynamicConfig<rustc_query_system[f56bcbed907ebf29]::query::caches::SingleCache<rustc_middle[f2b601c0ba6c1077]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[fe09369826c2ba2]::plumbing::QueryCtxt, false>
  24:        0x10f71e39a - rustc_query_impl[fe09369826c2ba2]::query_impl::resolver_for_lowering::get_query_non_incr::__rust_end_short_backtrace
  25:        0x10bb705d6 - <rustc_middle[f2b601c0ba6c1077]::ty::context::GlobalCtxt>::enter::<rustc_driver_impl[8cf711d4d0fcadf9]::run_compiler::{closure#1}::{closure#2}::{closure#4}, &rustc_data_structures[4d7720560792e628]::steal::Steal<(rustc_middle[f2b601c0ba6c1077]::ty::ResolverAstLowering, alloc[74d386d8e8450bf7]::rc::Rc<rustc_ast[fdc19c2a1ab7c13f]::ast::Crate>)>>
  26:        0x10bb95476 - rustc_span[68ec3145a42ee6ed]::set_source_map::<core[30426629a36827b9]::result::Result<(), rustc_span[68ec3145a42ee6ed]::ErrorGuaranteed>, rustc_interface[35dd32b46cf34317]::interface::run_compiler<core[30426629a36827b9]::result::Result<(), rustc_span[68ec3145a42ee6ed]::ErrorGuaranteed>, rustc_driver_impl[8cf711d4d0fcadf9]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  27:        0x10bb7a82c - std[671f820cec1cf149]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[35dd32b46cf34317]::util::run_in_thread_with_globals<rustc_interface[35dd32b46cf34317]::interface::run_compiler<core[30426629a36827b9]::result::Result<(), rustc_span[68ec3145a42ee6ed]::ErrorGuaranteed>, rustc_driver_impl[8cf711d4d0fcadf9]::run_compiler::{closure#1}>::{closure#0}, core[30426629a36827b9]::result::Result<(), rustc_span[68ec3145a42ee6ed]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[30426629a36827b9]::result::Result<(), rustc_span[68ec3145a42ee6ed]::ErrorGuaranteed>>
  28:        0x10bb7bfde - <<std[671f820cec1cf149]::thread::Builder>::spawn_unchecked_<rustc_interface[35dd32b46cf34317]::util::run_in_thread_with_globals<rustc_interface[35dd32b46cf34317]::interface::run_compiler<core[30426629a36827b9]::result::Result<(), rustc_span[68ec3145a42ee6ed]::ErrorGuaranteed>, rustc_driver_impl[8cf711d4d0fcadf9]::run_compiler::{closure#1}>::{closure#0}, core[30426629a36827b9]::result::Result<(), rustc_span[68ec3145a42ee6ed]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[30426629a36827b9]::result::Result<(), rustc_span[68ec3145a42ee6ed]::ErrorGuaranteed>>::{closure#1} as core[30426629a36827b9]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  30:     0x7ff8093191d3 - __pthread_start

error: 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 1.75.0-nightly (20b9ec86b 2023-10-09) running on x86_64-apple-darwin

note: compiler flags: -Z threads=1 -Z simulate-remapped-rust-src-base=/rustc/FAKE_PREFIX -Z translate-remapped-path-to-local-path=no -Z ignore-directory-in-diagnostics-source-blocks=/Users/runner/.cargo -C codegen-units=1 -Z ui-testing -Z deduplicate-diagnostics=no -Z write-long-types-to-disk=no -C strip=debuginfo -C prefer-dynamic -C rpath -C debuginfo=0 -Z treat-err-as-bug=1
query stack during panic:
#0 [resolver_for_lowering] getting the resolver for lowering
end of query stack
------------------------------------------

[bors]

💔 Test failed - checks-actions

[aliemjay]

probably unrelated?
@bors retry rollup

[aliemjay]

what kinds of programs ICE if you change tis to a bug! instead?

A handful of ui tests. All of which involve a TyKind::Error, either in the query or because of an invalid trait impls.