Bootstrapping fails with --opt-level=1

[alexcrichton]

Sadly, I'm unable to reduce this test case further, but bootstrapping rust with --opt-level=1 causes an assertion failure:

$ ./configure --disable-optimize
...
$ make RUSTFLAGS=--opt-level=1
...
oxidize: x86_64-unknown-linux-gnu/stage1/lib/rustlib/x86_64-unknown-linux-gnu/lib/libstd
task '<main>' failed at 'assertion failed: !contains_nul(path.container_as_bytes())', /home/alex/code/rust2/src/libs
td/path/mod.rs:161
make: *** [x86_64-unknown-linux-gnu/stage1/lib/rustlib/x86_64-unknown-linux-gnu/lib/stamp.std] Error 101
stack backtrace:
   1:     0x2afc8575d3d0 - rt::backtrace::imp::write::hf4a317cb26f6dbdcCYb::v0.11.pre
   2:     0x2afc8568f320 - rt::unwind::begin_unwind_inner::hc4d1b90c74aff9505yb::v0.11.pre
   3:     0x2afc8568ee80 - rt::unwind::begin_unwind_fmt::ha138a63726a8610ffyb::v0.11.pre
   4:     0x2afc88ab51b0 - path::GenericPath::new::h9338406b1241c33bhtc::v0.11.pre
   5:     0x2afc88ab5160 - path::posix::Path::new::hc0024b98d3428ebe3sc::v0.11.pre
   6:     0x2afc88aaee90 - terminfo::searcher::get_dbpath_for_term::hb9860c7e7fc3fd526aa::v0.11.pre
   7:     0x2afc88ab6650 - terminfo::searcher::open::hf62724575cfe88cbhfa::v0.11.pre
   8:     0x2afc86659550 - Terminal$LT$T$GT$::new::hdabfc77b7ac55d88Qo5::v0.11.pre
   9:     0x2afc86652420 - diagnostic::EmitterWriter::stderr::hfd23d008f940811626b::v0.11.pre
  10:     0x2afc8351b620 - monitor::hba5a4a2b7e13d4ecikm::v0.11.pre
  11:     0x2afc835370d0 - main_args::hbd9a5c72232d6063Qom::v0.11.pre
  12:     0x2afc83537040 - main::h69153f0097da5909Gom::v0.11.pre
  13:     0x2afc853dd240 - run::hf16768b59fb57517ixd::v0.11.pre
  14:     0x2afc853dd180 - start::closure.7826
  15:     0x2afc857564d0 - unstable::finally::try_finally::h8293b253ac1a0b2fP9U::v0.11.pre
  16:     0x2afc85756440 - unstable::finally::_$x27a$x7c$x7c$x20.$GT$$x20T.Finally$LT$T$GT$::finally::ha3168e974cad9
dd5v8U::v0.11.pre
  17:     0x2afc857563e0 - rt::task::Task::run::closure.41772
  18:     0x2afc857672b0 - rust_try
  19:     0x2afc85756b70 - rt::unwind::Unwinder::try::h072d99d58e638ae0Wkb::v0.11.pre
  20:     0x2afc85756300 - rt::task::Task::run::hdd5dcbf94d6bade1Br9::v0.11.pre
  21:     0x2afc853dcc10 - start::h4100553b9a0fcee0Ktd::v0.11.pre
  22:     0x2afc853dcb90 - lang_start::he63000f25bb5087f4sd::v0.11.pre
  23:     0x2afc85e11cf0 - __libc_start_main
  24:           0x400780 - <unknown>
  25:                0x0 - <unknown>

This is because Path::new("/etc/terminfo") is failing, because it thinks there's a null byte in that slice. I added some debug printing and the slice did indeed not have a null byte, but the contains_nul function returned true anyway. Additionally, if I inlined the contents of contains_nul it correctly reported that the slice did not have a nul byte.

This may be fixed with an LLVM upgrade, but I wanted to get an issue to help track this.

[alexcrichton]

By extracting the path module into its own crate, I was unable to reproduce this in an isolated test case.

If you have a stage0 copy of libstd built with --opt-level=1, the failure is exhibited by this program:

fn main() {
    Path::new("/etc/terminfo");
}

I believe the minimal reproduction steps are then:

$ ./configure --disable-optimize
...
$ export target=x86_64-unknown-linux-gnu
$ make RUSTFLAGS=--opt-level=1 $target/stage0/lib/rustlib/$target/lib/stamp.{std,native}
...
$ ./$target/stage0/bin/rustc foo.rs --opt-level=1
$ ./foo
task '<main>' failed at 'assertion failed: !contains_nul(path.container_as_bytes())', /home/alex/code/rust2/src/libstd/path/mod.rs:161                                                                                                  

[alexcrichton]

Ok, things are even weirder. On OSX, this command just hits an infinite loop in LLVM

./x86_64-apple-darwin/stage0/bin/rustc --cfg stage0 --opt-level=1 ./src/libstd/lib.rs

[alexcrichton]

I updated LLVM, and I'm unsure if that helped here. The LLVM update causes rustc to generate binaries that instantly segfault.

[alexcrichton]

This appears to have been fixed, I presume by an LLVM upgrade at some point.