Nightly crashes trying to compile a naked function macro with inline asm

[hexonxon]

Building https://is.gd/qud5dG with nightly 10-07 and 10-20 crashes with the following message:

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

thread 'rustc' panicked at 'index out of bounds: the len is 0 but the index is 78', ../src/libcollections/vec.rs:1306

[nagisa]

stack backtrace:
   1:     0x7fb32df949df - std::sys::backtrace::tracing::imp::write::h22f199c1dbb72ba2
   2:     0x7fb32dfa3f0d - std::panicking::default_hook::{{closure}}::h9a389c462b6a22dd
   3:     0x7fb32dfa1386 - std::panicking::default_hook::h852b4223c1c00c59
   4:     0x7fb32dfa1a68 - std::panicking::rust_panic_with_hook::hcd9d05f53fa0dafc
   5:     0x7fb32dfa1902 - std::panicking::begin_panic::hf6c488cee66e7f17
   6:     0x7fb32dfa1840 - std::panicking::begin_panic_fmt::hb0a7126ee57cdd27
   7:     0x7fb32dfa17c1 - rust_begin_unwind
   8:     0x7fb32dfef6df - core::panicking::panic_fmt::h9af671b78898cdba
   9:     0x7fb32dfef683 - core::panicking::panic_bounds_check::h56f656aa4e352200
  10:     0x7fb32a68a802 - syntax::ast::Name::as_str::h38b25568cfeb8bbd
  11:     0x7fb32a68a8cc - <syntax::ast::Name as core::fmt::Display>::fmt::h82dc8d66519a98d5
  12:     0x7fb32dff1975 - core::fmt::write::he349f75ae1aca1a1
  13:     0x7fb32dfac730 - collections::fmt::format::h4276955d08ba3cf1
  14:     0x7fb32a698fea - syntax::codemap::CodeMap::macro_backtrace::h34dc4db4c69f95f8
  15:     0x7fb32a69930e - <syntax::codemap::CodeMap as rustc_errors::CodeMapper>::macro_backtrace::h66edae518ba75521
  16:     0x7fb32a3de6e7 - rustc_errors::emitter::EmitterWriter::fix_multispan_in_std_macros::h64647a5ae27a40eb
  17:     0x7fb32a3dbda6 - <rustc_errors::emitter::EmitterWriter as rustc_errors::emitter::Emitter>::emit::hf391e61324782492
  18:     0x7fb32a3e8e38 - rustc_errors::Handler::emit::hb6211616feb773be
  19:     0x7fb32cb04232 - rustc::session::Session::span_err::hc0a7da3b1ecabc87
  20:     0x7fb32cb32750 - rustc_trans::back::write::report_inline_asm::hcc7f5c5fe2807a91
  21:     0x7fb32cb32843 - rustc_trans::back::write::inline_asm_handler::h024a8afb079c4f0b
  22:     0x7fb3283c83b6 - _ZN12_GLOBAL__N_19AsmParser11DiagHandlerERKN4llvm12SMDiagnosticEPv
  23:     0x7fb32862713d - _ZNK4llvm9SourceMgr12PrintMessageERNS_11raw_ostreamENS_5SMLocENS0_8DiagKindERKNS_5TwineENS_8ArrayRefINS_7SMRangeEEENS8_INS_7SMFixItEEEb
  24:     0x7fb3286272fb - _ZNK4llvm9SourceMgr12PrintMessageENS_5SMLocENS0_8DiagKindERKNS_5TwineENS_8ArrayRefINS_7SMRangeEEENS6_INS_7SMFixItEEEb
  25:     0x7fb3283bdf8e - _ZN12_GLOBAL__N_19AsmParser5ErrorEN4llvm5SMLocERKNS1_5TwineENS1_8ArrayRefINS1_7SMRangeEEE
  26:     0x7fb32773c8b4 - _ZN12_GLOBAL__N_112X86AsmParser19ErrorMissingFeatureEN4llvm5SMLocEmb
  27:     0x7fb327747d5d - _ZN12_GLOBAL__N_112X86AsmParser28MatchAndEmitIntelInstructionEN4llvm5SMLocERjRNS1_15SmallVectorImplISt10unique_ptrINS1_18MCParsedAsmOperandESt14default_deleteIS6_EEEERNS1_10MCStreamerERmb
  28:     0x7fb3283d46fa - _ZN12_GLOBAL__N_19AsmParser14parseStatementERNS_18ParseStatementInfoEPN4llvm23MCAsmParserSemaCallbackE
  29:     0x7fb3283d565e - _ZN12_GLOBAL__N_19AsmParser3RunEbb
  30:     0x7fb327aed544 - _ZNK4llvm10AsmPrinter13EmitInlineAsmENS_9StringRefERKNS_15MCSubtargetInfoERKNS_15MCTargetOptionsEPKNS_6MDNodeENS_9InlineAsm10AsmDialectE
  31:     0x7fb327aedd43 - _ZNK4llvm10AsmPrinter13EmitInlineAsmEPKNS_12MachineInstrE
  32:     0x7fb327aea842 - _ZN4llvm10AsmPrinter16EmitFunctionBodyEv
  33:     0x7fb327753f9d - _ZN4llvm13X86AsmPrinter20runOnMachineFunctionERNS_15MachineFunctionE
  34:     0x7fb327ca027a - _ZN4llvm19MachineFunctionPass13runOnFunctionERNS_8FunctionE
  35:     0x7fb32857cbd6 - _ZN4llvm13FPPassManager13runOnFunctionERNS_8FunctionE
  36:     0x7fb32857cc1a - _ZN4llvm13FPPassManager11runOnModuleERNS_6ModuleE
  37:     0x7fb32857e7ee - _ZN4llvm6legacy15PassManagerImpl3runERNS_6ModuleE
  38:     0x7fb326fb6285 - LLVMRustWriteOutputFile
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/src/rustllvm/PassWrapper.cpp:489
  39:     0x7fb32cb314f3 - rustc_trans::back::write::write_output_file::h7e8cf29735c33835
  40:     0x7fb32cbd7c3e - rustc_trans::back::write::optimize_and_codegen::{{closure}}::h368ad232bd936447
  41:     0x7fb32cb390ca - rustc_trans::back::write::execute_work_item::h11850bd68a6e29be
  42:     0x7fb32cb33b19 - rustc_trans::back::write::run_passes::h17498b78d8227324
  43:     0x7fb32e32adbf - rustc_driver::driver::phase_5_run_llvm_passes::h11938d38ef5db27c
  44:     0x7fb32e314232 - rustc_driver::driver::compile_input::h5b63ccd49eeeb98b
  45:     0x7fb32e33d2ba - rustc_driver::run_compiler::h98c7274e7cb1d11d
  46:     0x7fb32e276f0b - std::panicking::try::do_call::h99ed0da044e497c3
  47:     0x7fb32dfabe06 - __rust_maybe_catch_panic
  48:     0x7fb32e295461 - <F as alloc::boxed::FnBox<A>>::call_box::hbdd5a14cd8e33b97
  49:     0x7fb32df9fde0 - std::sys::thread::Thread::new::thread_start::h50b05608a499d2b2
  50:     0x7fb3262836f9 - start_thread
  51:     0x7fb32dc63b5c - clone
  52:                0x0 - <unknown>

Minimised:

#![crate_type="lib"]
#![feature(asm)]

macro_rules! interrupt_handler {
    () => {
        unsafe fn interrupt_handler() {
            asm!("pop  eax" :::: "intel");
        }
    }
}
interrupt_handler!{}

It seems like we fail at reporting the error in question through the macros somehow.

[eddyb]

We're trying to report in report_inline_asm but the ident interner is gone - guess we can't ever clear it?
cc @jseyfried

[hexonxon]

Maybe this might help as well. Locally i build for i686-unknown-linux-gnu target and sometimes it actually builds fine without crashes, errors or warnings, and then runs. I haven't been able to pinpoint specific change that makes this inline asm piece not crash the compiler, sometimes it just works. Also, locally usually release target crashes and not debug (playground does the opposite).

[jseyfried]

@Warfish I believe this was fixed by #37824.

[Mark-Simulacrum]

Unassigning since @jseyfried probably isn't going to be the one to add the test.