Repository: rust
Issue: ICE: `Got a scalar pair where a scalar was expected`
Labels: I-ICE,T-compiler,C-bug,A-mir-opt,S-bug-has-test,F-trivial_bounds,A-mir-opt-GVN

<!--
[31mICE[0m: Rustc ./DF27EFC1C888D51AA6273A0D770795B64EF20F832FEC125939D70C3B424E39F8.rs '-Zmir-opt-level=5 -Zcrate-attr=feature(trivial_bounds) --crate-type=lib -ooutputfile -Zdump-mir-dir=dir' 'error: internal compiler error: /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/compiler/rustc_const_eval/src/interpret/operand.rs:82:42: Got a scalar pair where a scalar was expected', 'error: internal compiler error: /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/compiler/rustc_const_eval/src/interpret/operand.rs:82:42: Got a scalar pair where a scalar was expected'
File: /tmp/im/DF27EFC1C888D51AA6273A0D770795B64EF20F832FEC125939D70C3B424E39F8.rs
-->

auto-reduced (treereduce-rust):
````rust
#![feature(trivial_bounds)]

#[derive(Debug)]
struct TwoStrs(str, str)
where
    str: Sized;

````

original:
````rust
#[derive(Debug)]
struct Foo(i32);

#[derive(Debug)]
struct TwoStrs(str, str) where str: Sized;

````

Version information
````
rustc 1.78.0-nightly (bb594538f 2024-02-20)
binary: rustc
commit-hash: bb594538fc6e84213a6b8d5e165442570aa48923
commit-date: 2024-02-20
host: x86_64-unknown-linux-gnu
release: 1.78.0-nightly
LLVM version: 18.1.0

````

Command:
`/home/matthias/.rustup/toolchains/master/bin/rustc -Zmir-opt-level=5 -Zcrate-attr=feature(trivial_bounds) --crate-type=lib`

<!--
Include a backtrace in the code block by setting `RUST_BACKTRACE=1` in your
environment. E.g. `RUST_BACKTRACE=1 cargo build`.
-->
<details><summary><strong>Program output</strong></summary>
<p>

```
warning: struct `TwoStrs` is never constructed
 --> /tmp/icemaker_global_tempdir.d7BGTl8YHHxI/rustc_testrunner_tmpdir_reporting.Zw6CwslhbT5j/mvce.rs:2:8
  |
2 | struct TwoStrs(str, str)
  |        ^^^^^^^
  |
  = note: `TwoStrs` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
  = note: `#[warn(dead_code)]` on by default

warning: trait bound str: Sized does not depend on any type or lifetime parameters
 --> /tmp/icemaker_global_tempdir.d7BGTl8YHHxI/rustc_testrunner_tmpdir_reporting.Zw6CwslhbT5j/mvce.rs:4:10
  |
4 |     str: Sized;
  |          ^^^^^
  |
  = note: `#[warn(trivial_bounds)]` on by default

error: internal compiler error: /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/compiler/rustc_const_eval/src/interpret/operand.rs:82:42: Got a scalar pair where a scalar was expected

thread 'rustc' panicked at compiler/rustc_middle/src/util/bug.rs:35:44:
Box<dyn Any>
stack backtrace:
   0:     0x7ff23b050af6 - std::backtrace_rs::backtrace::libunwind::trace::h1eedb42239d9af6b
                               at /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/library/std/src/../../backtrace/src/backtrace/libunwind.rs:104:5
   1:     0x7ff23b050af6 - std::backtrace_rs::backtrace::trace_unsynchronized::hf37e37075d32c152
                               at /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7ff23b050af6 - std::sys_common::backtrace::_print_fmt::h089ff4e21712e78d
                               at /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7ff23b050af6 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h249f2f40a85530bd
                               at /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7ff23b0a1a7c - core::fmt::rt::Argument::fmt::h0aeed2b676ebf5da
                               at /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/library/core/src/fmt/rt.rs:142:9
   5:     0x7ff23b0a1a7c - core::fmt::write::h25b3f5340152b6c4
                               at /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/library/core/src/fmt/mod.rs:1120:17
   6:     0x7ff23b04542f - std::io::Write::write_fmt::h8746a81e0adfe285
                               at /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/library/std/src/io/mod.rs:1846:15
   7:     0x7ff23b0508a4 - std::sys_common::backtrace::_print::hcf22409f3667d346
                               at /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7ff23b0508a4 - std::sys_common::backtrace::print::h7d3fd33863df24d3
                               at /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7ff23b0535eb - std::panicking::default_hook::{{closure}}::h69f3f4f5b3bceec1
  10:     0x7ff23b053339 - std::panicking::default_hook::hf73563d650f0e118
                               at /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/library/std/src/panicking.rs:292:9
  11:     0x7ff237e1a63c - std[38a2ac7f7aa65357]::panicking::update_hook::<alloc[250c3b7c6f6c60ed]::boxed::Box<rustc_driver_impl[98bdfcf9c8fb7ba2]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7ff23b053d50 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h0f1d4fd9cb21869d
                               at /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/library/alloc/src/boxed.rs:2030:9
  13:     0x7ff23b053d50 - std::panicking::rust_panic_with_hook::h55549baaf7aa2e9c
                               at /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/library/std/src/panicking.rs:786:13
  14:     0x7ff237e47244 - std[38a2ac7f7aa65357]::panicking::begin_panic::<rustc_errors[31b00c9a61d6a627]::ExplicitBug>::{closure#0}
  15:     0x7ff237e43e96 - std[38a2ac7f7aa65357]::sys_common::backtrace::__rust_end_short_backtrace::<std[38a2ac7f7aa65357]::panicking::begin_panic<rustc_errors[31b00c9a61d6a627]::ExplicitBug>::{closure#0}, !>
  16:     0x7ff237e3f626 - std[38a2ac7f7aa65357]::panicking::begin_panic::<rustc_errors[31b00c9a61d6a627]::ExplicitBug>
  17:     0x7ff237e51ad1 - <rustc_errors[31b00c9a61d6a627]::diagnostic_builder::BugAbort as rustc_errors[31b00c9a61d6a627]::diagnostic_builder::EmissionGuarantee>::emit_producing_guarantee
  18:     0x7ff2382247ec - <rustc_errors[31b00c9a61d6a627]::DiagCtxt>::bug::<alloc[250c3b7c6f6c60ed]::string::String>
  19:     0x7ff2382c76eb - rustc_middle[cfb3c689534e2244]::util::bug::opt_span_bug_fmt::<rustc_span[39701832932d6f53]::span_encoding::Span>::{closure#0}
  20:     0x7ff2382ac41a - rustc_middle[cfb3c689534e2244]::ty::context::tls::with_opt::<rustc_middle[cfb3c689534e2244]::util::bug::opt_span_bug_fmt<rustc_span[39701832932d6f53]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  21:     0x7ff2382ac2b8 - rustc_middle[cfb3c689534e2244]::ty::context::tls::with_context_opt::<rustc_middle[cfb3c689534e2244]::ty::context::tls::with_opt<rustc_middle[cfb3c689534e2244]::util::bug::opt_span_bug_fmt<rustc_span[39701832932d6f53]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  22:     0x7ff236740bc0 - rustc_middle[cfb3c689534e2244]::util::bug::bug_fmt
  23:     0x7ff2395a8f6b - <rustc_mir_transform[3a9949066bb08602]::gvn::VnState>::simplify_operand
  24:     0x7ff2370be253 - <rustc_mir_transform[3a9949066bb08602]::gvn::GVN as rustc_middle[cfb3c689534e2244]::mir::MirPass>::run_pass
  25:     0x7ff239012649 - rustc_mir_transform[3a9949066bb08602]::pass_manager::run_passes_inner
  26:     0x7ff2394a84bf - rustc_mir_transform[3a9949066bb08602]::optimized_mir
  27:     0x7ff239073c75 - rustc_query_impl[72e671e77ccdc0fd]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[72e671e77ccdc0fd]::query_impl::optimized_mir::dynamic_query::{closure#2}::{closure#0}, rustc_middle[cfb3c689534e2244]::query::erase::Erased<[u8; 8usize]>>
  28:     0x7ff239074321 - rustc_query_system[eb6d0acd22a0ff82]::query::plumbing::try_execute_query::<rustc_query_impl[72e671e77ccdc0fd]::DynamicConfig<rustc_query_system[eb6d0acd22a0ff82]::query::caches::DefIdCache<rustc_middle[cfb3c689534e2244]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[72e671e77ccdc0fd]::plumbing::QueryCtxt, false>
  29:     0x7ff239073a9e - rustc_query_impl[72e671e77ccdc0fd]::query_impl::optimized_mir::get_query_non_incr::__rust_end_short_backtrace
  30:     0x7ff239453461 - rustc_middle[cfb3c689534e2244]::query::plumbing::query_get_at::<rustc_query_system[eb6d0acd22a0ff82]::query::caches::DefIdCache<rustc_middle[cfb3c689534e2244]::query::erase::Erased<[u8; 8usize]>>>
  31:     0x7ff239f9d7fd - <rustc_metadata[7844668d1f998472]::rmeta::encoder::EncodeContext>::encode_crate_root
  32:     0x7ff239fdf116 - rustc_metadata[7844668d1f998472]::rmeta::encoder::encode_metadata
  33:     0x7ff239fdd2b8 - rustc_metadata[7844668d1f998472]::fs::encode_and_write_metadata
  34:     0x7ff239fdc65d - rustc_interface[d43ea88de449c898]::passes::start_codegen
  35:     0x7ff239fdbed8 - <rustc_interface[d43ea88de449c898]::queries::Queries>::codegen_and_build_linker
  36:     0x7ff239d6482d - rustc_interface[d43ea88de449c898]::interface::run_compiler::<core[9082f35584c4c405]::result::Result<(), rustc_span[39701832932d6f53]::ErrorGuaranteed>, rustc_driver_impl[98bdfcf9c8fb7ba2]::run_compiler::{closure#0}>::{closure#0}
  37:     0x7ff239fc1c05 - std[38a2ac7f7aa65357]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[d43ea88de449c898]::util::run_in_thread_with_globals<rustc_interface[d43ea88de449c898]::util::run_in_thread_pool_with_globals<rustc_interface[d43ea88de449c898]::interface::run_compiler<core[9082f35584c4c405]::result::Result<(), rustc_span[39701832932d6f53]::ErrorGuaranteed>, rustc_driver_impl[98bdfcf9c8fb7ba2]::run_compiler::{closure#0}>::{closure#0}, core[9082f35584c4c405]::result::Result<(), rustc_span[39701832932d6f53]::ErrorGuaranteed>>::{closure#0}, core[9082f35584c4c405]::result::Result<(), rustc_span[39701832932d6f53]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[9082f35584c4c405]::result::Result<(), rustc_span[39701832932d6f53]::ErrorGuaranteed>>
  38:     0x7ff239fc1a32 - <<std[38a2ac7f7aa65357]::thread::Builder>::spawn_unchecked_<rustc_interface[d43ea88de449c898]::util::run_in_thread_with_globals<rustc_interface[d43ea88de449c898]::util::run_in_thread_pool_with_globals<rustc_interface[d43ea88de449c898]::interface::run_compiler<core[9082f35584c4c405]::result::Result<(), rustc_span[39701832932d6f53]::ErrorGuaranteed>, rustc_driver_impl[98bdfcf9c8fb7ba2]::run_compiler::{closure#0}>::{closure#0}, core[9082f35584c4c405]::result::Result<(), rustc_span[39701832932d6f53]::ErrorGuaranteed>>::{closure#0}, core[9082f35584c4c405]::result::Result<(), rustc_span[39701832932d6f53]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[9082f35584c4c405]::result::Result<(), rustc_span[39701832932d6f53]::ErrorGuaranteed>>::{closure#1} as core[9082f35584c4c405]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  39:     0x7ff23b05d725 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h8e2928e2096a726d
                               at /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/library/alloc/src/boxed.rs:2016:9
  40:     0x7ff23b05d725 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h4f25e5317edfd617
                               at /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/library/alloc/src/boxed.rs:2016:9
  41:     0x7ff23b05d725 - std::sys::pal::unix::thread::Thread::new::thread_start::hc7193b55f6b48c9a
                               at /rustc/bb594538fc6e84213a6b8d5e165442570aa48923/library/std/src/sys/pal/unix/thread.rs:108:17
  42:     0x7ff234eaa9eb - <unknown>
  43:     0x7ff234f2e7cc - <unknown>
  44:                0x0 - <unknown>

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 1.78.0-nightly (bb594538f 2024-02-20) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z mir-opt-level=5 -Z crate-attr=feature(trivial_bounds) --crate-type lib -Z dump-mir-dir=dir

query stack during panic:
#0 [optimized_mir] optimizing MIR for `<impl at /tmp/icemaker_global_tempdir.d7BGTl8YHHxI/rustc_testrunner_tmpdir_reporting.Zw6CwslhbT5j/mvce.rs:1:10: 1:15>::fmt`
end of query stack
error: aborting due to 1 previous error; 2 warnings emitted


```

</p>
</details>

<!--
query stack:
#0 [optimized_mir] optimizing MIR for `<impl at /tmp/icemaker_global_tempdir.d7BGTl8YHHxI/rustc_testrunner_tmpdir_reporting.Zw6CwslhbT5j/mvce.rs:1:10: 1:15>::fmt`

-->