assertion failed: bpos.to_usize() >= mbc.pos.to_usize() + mbc.bytes

[Ms2ger]

Hit on running ./mach test-unit on https://github.com/Ms2ger/servo/tree/rustc-bug-codemap on travis.

12.18s$ ./mach test-unit

   Compiling util_tests v0.0.1 (file:///home/travis/build/servo/servo/tests/unit/util)

   Compiling profile_tests v0.0.1 (file:///home/travis/build/servo/servo/tests/unit/profile)

   Compiling net_traits_tests v0.0.1 (file:///home/travis/build/servo/servo/tests/unit/net_traits)

   Compiling net_tests v0.0.1 (file:///home/travis/build/servo/servo/tests/unit/net)

   Compiling gfx_tests v0.0.1 (file:///home/travis/build/servo/servo/tests/unit/gfx)

   Compiling script_tests v0.0.1 (file:///home/travis/build/servo/servo/tests/unit/script)

   Compiling layout_tests v0.0.1 (file:///home/travis/build/servo/servo/tests/unit/layout)

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: run with `RUST_BACKTRACE=1` for a backtrace

thread 'rustc' panicked at 'assertion failed: bpos.to_usize() >= mbc.pos.to_usize() + mbc.bytes', ../src/libsyntax/codemap.rs:707

stack backtrace:

   1:     0x7f623f0f79df - std::sys::backtrace::tracing::imp::write::h22f199c1dbb72ba2

   2:     0x7f623f106f0d - std::panicking::default_hook::{{closure}}::h9a389c462b6a22dd

   3:     0x7f623f104386 - std::panicking::default_hook::h852b4223c1c00c59

   4:     0x7f623f104a68 - std::panicking::rust_panic_with_hook::hcd9d05f53fa0dafc

   5:     0x7f623b79a92f - std::panicking::begin_panic::hc03e2830c2c89a5f

   6:     0x7f623b7ff9c0 - syntax::codemap::CodeMap::bytepos_to_file_charpos::h3e1ecefe8c872433

   7:     0x7f623b7fc85f - syntax::codemap::CodeMap::lookup_char_pos::hfba960093e9845af

   8:     0x7f623dd0e8d7 - rustc_trans::mir::MirContext::scope_metadata_for_loc::hf4ec7e4a54af690a

   9:     0x7f623dd0e71c - rustc_trans::mir::MirContext::debug_loc::h081d6b2d00268062

  10:     0x7f623dd12a44 - rustc_trans::mir::block::<impl rustc_trans::mir::MirContext<'bcx, 'tcx>>::trans_block::he67d3259f79e4177

  11:     0x7f623dd10b58 - rustc_trans::mir::trans_mir::h2fb44ecb31cfdffa

  12:     0x7f623dcb2cdc - rustc_trans::base::trans_closure::h941de14309416d66

  13:     0x7f623dd30a34 - rustc_trans::trans_item::TransItem::define::ha4a18b94a3d46bf3

  14:     0x7f623dcb6254 - rustc_trans::base::trans_crate::h9b06de31ed8799d1

  15:     0x7f623f48cd4d - rustc_driver::driver::phase_4_translate_to_llvm::hc3883ea2c4750179

  16:     0x7f623f4c7cf7 - rustc_driver::driver::compile_input::{{closure}}::h9162a2fa292aeb3f

  17:     0x7f623f4beef3 - rustc_driver::driver::phase_3_run_analysis_passes::{{closure}}::h1928c4704cfe9c61

  18:     0x7f623f48a6ed - rustc_driver::driver::phase_3_run_analysis_passes::he578df6b8805151c

  19:     0x7f623f476f69 - rustc_driver::driver::compile_input::h5b63ccd49eeeb98b

  20:     0x7f623f4a02ba - rustc_driver::run_compiler::h98c7274e7cb1d11d

  21:     0x7f623f3d9f0b - std::panicking::try::do_call::h99ed0da044e497c3

  22:     0x7f623f10ee06 - __rust_maybe_catch_panic

  23:     0x7f623f3f8461 - <F as alloc::boxed::FnBox<A>>::call_box::hbdd5a14cd8e33b97

  24:     0x7f623f102de0 - std::sys::thread::Thread::new::thread_start::h50b05608a499d2b2

  25:     0x7f62373da183 - start_thread

  26:     0x7f623edbe37c - clone

  27:                0x0 - <unknown>

Build failed, waiting for other jobs to finish...

error: Could not compile `net_tests`.

To learn more, run the command again with --verbose.

The command "./mach test-unit" exited with 101.

[SimonSapin]

Looks like the failing assertion is the same as in #24687, which was fixed in #24932. CC @pnkfelix who made that fix.

[SimonSapin]

IIRC @nox worked around another instance of the same assertion failure by removing some non-ASCII characters in a string constant (replacing them with \u{…}) in a dependency of the crate failing to compile.

[nox]

I can confirm.

[nox]

It didn't help this time though, can't find any UTF-8 stuff to remove for that crate, even transitively.

[TimNN]

I tried to look into this:

• I can reproduce this on linux
• I looked a bit at the syntax=debug log, and it may be possible that the problematic chars originate from a proc-macro generated input Edit: apparently not

[TimNN]

Forget my last comment, apparently the problematic file is lib.rs from the url crate, which contains a non-unicode character in a doc comment: https://github.com/servo/rust-url/blob/master/src/lib.rs#L765

[nox]

@TimNN Maybe, but most files in rust-url are UTF-8 encoded with fancy chars, this definitely needs a rustc fix because we can't decently work around it.

[TimNN]

@nox: So it's still failing?

I agree that this needs a proper fix in rustc, however the problem seems to be annoyingly hard to debug: the syntax=debug log is practically useless (at least to me) and I cannot easily reproduce this problem: just having an extern crate with fancy chars in doc comments & using it does not trigger the problem.

[pnkfelix]

Okay I have reduced this problem down to a set of four crates, themselves reduced from the Servo source.

(The four crates still are relying on a number of other crates in the crates.io ecosystem, most notably Serde.)

https://github.com/pnkfelix/rust-issues/tree/issue-37274