Corrupt backtrace printing

[bjorn3]

The panic is caused by a problem in my code, but I expected a backtrace without garbage like U▒.

$ rustc -V
rustc 1.43.0-nightly (3dbade652 2020-03-09)
$ git clone https://github.com/bjorn3/rustc_codegen_cranelift
$ cd rustc_codegen_cranelift
$ git checkout 3e111967d297173b410ed4ad174e5bb0379ed6a2
$ ./prepare.sh && ./test.sh
$ # You can abort the previous command once hyperfine is running
$ cd simple-raytracer
$ CG_CLIF_INCR_CACHE=1 ../cargo.sh build
$ rm target/x86_64-unknown-linux-gnu/debug/deps/libraytracer-*.rlib
$ CG_CLIF_INCR_CACHE=1 ../cargo.sh build
$ # The broken backtrace

Sorry for the long repro steps. I don't know how to reduce this.

thread 'rustc' panicked at 'LTO unsupported', src/driver.rs:291:38
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.44/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.44/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:78
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:59
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1063
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1428
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:62
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:204
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:224
  10: rustc_driver::report_ice
  11: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:474
  12: is_prefix_of17h94b348dc8c888b79E
  13: teral4span17h10eecf4264bfcf69E
  14: U▒
  15: core::iter::traits::iterator::Iterator::fold::ok::{{closure}}
  16: core::iter::traits::iterator::Iterator::try_fold
  17: 
  18: U▒
  19: 
  20: 
  21: �/
  22: 
  23: oc_macro28fallback5Ident4span17h67e781d6d0fd26b5E
  24: f9b2563E
  25: macro26strnom6Cursor4find17h96007a5d5e73adc2E
  26: into_iter28_$u7b$$u7b$closure$u7d$$u7d$17he06b301940fa9f5cE
  27: cept_table107
  28: rustc_codegen_cranelift::driver::codegen_crate
  29: <rustc_codegen_cranelift::CraneliftCodegenBackend as rustc_codegen_utils::codegen_backend::CodegenBackend>::codegen_crate
  30: rustc_interface::passes::start_codegen
  31: rustc::ty::context::tls::enter_global
  32: rustc_interface::queries::Queries::ongoing_codegen
  33: rustc_interface::interface::run_compiler_in_existing_thread_pool
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose 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/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.43.0-nightly (3dbade652 2020-03-09) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z panic-abort-tests -Z codegen-backend=/home/bjorn/Documenten/cg_clif/target/debug/librustc_codegen_cranelift.so -C debuginfo=2 -C incremental -C panic=abort -C debuginfo=2 --crate-type lib

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
end of query stack

(bjorn3/rustc_codegen_cranelift@3e11196 keep alive for this commit)

[Aaron1011]

@bjorn3: Can you check if this is an instance of #69151 (i.e. the debuginfo is too large)?

[bjorn3]

The total size of the target dir is less than 2GB, so debuginfo shouldn't be too large.

[bjorn3]

Haven't seen this since.