Segfault Compiling Rust Completer

[landersson]

Hi,

I'm getting a segmentation fault when trying to build the rust completer under Mac OS X 10.11.6 using rust stable 1.26:

Running `/Users/larsandersson/dot-files/vim/vim/bundle/YouCompleteMe/third_party/ycmd/third_party/racerd/target/release/build/libracerd-575086e0e3f82a44/build-script-build`
error: failed to run custom build command for `libracerd v0.3.3 (file:///Users/larsandersson/dot-files/vim/vim/bundle/YouCompleteMe/third_party/ycmd/third_party/racerd)`
process didn't exit successfully: `/Users/larsandersson/dot-files/vim/vim/bundle/YouCompleteMe/third_party/ycmd/third_party/racerd/target/release/build/libracerd-575086e0e3f82a44/build-script-build` (signal: 11, SIGSEGV: invalid memory reference)

Looking at the backtrace, it seems to be related to serde:

(gdb) bt
#0  0x00000001001e6782 in syntex_syntax::attr::mk_attr_id::he4ed48d103165959 ()
#1  0x00000001000da465 in syntex::registry::Registry::add_attr::hb32c401bb765a68d ()
#2  0x0000000100037fc4 in serde_codegen::syntex_registry::ha9b6b03e61114f5f ()
#3  0x0000000100008c3a in std::sys_common::backtrace::__rust_begin_short_backtrace::h8ad45ce89ecd74f1 ()
#4  0x00000001000081f8 in std::panicking::try::do_call::h5433abda0ba4336f ()
#5  0x0000000100389f0f in __rust_maybe_catch_panic () at libpanic_unwind/lib.rs:102
#6  0x0000000100010ee8 in _$LT$F$u20$as$u20$alloc..boxed..FnBox$LT$A$GT$$GT$::call_box::h2843c289271ef279 ()
#7  0x000000010037d888 in from_error<std::sys::unix::fd::FileDesc,std::io::error::Error> () at /Users/travis/build/rust-lang/rust/src/libcore/result.rs:1209
#8  {{closure}} () at libstd/sys/unix/fd.rs:220
#9  call_once<closure,(i32)> () at /Users/travis/build/rust-lang/rust/src/libcore/ops/function.rs:223
#10 and_then<i32,std::io::error::Error,std::sys::unix::fd::FileDesc,closure> () at /Users/travis/build/rust-lang/rust/src/libcore/result.rs:621
#11 std::sys_common::thread::start_thread::hffc3810a6e03b74d () at libstd/sys/unix/fd.rs:244
#12 0x000000010036cc19 in unwrap_or_else<*mut u8,core::heap::AllocErr,closure> () at /Users/travis/build/rust-lang/rust/src/libcore/result.rs:748
#13 exchange_malloc () at /Users/travis/build/rust-lang/rust/src/liballoc/heap.rs:241
#14 new<std::error::{{impl}}::from::StringError> () at /Users/travis/build/rust-lang/rust/src/liballoc/boxed.rs:243
#15 from () at libstd/error.rs:195
#16 std::sys::unix::thread::Thread::new::thread_start::hbd2eb72915a2a86e () at libstd/error.rs:225
#17 0x00007fff903e399d in ?? ()

If anyone is planning to look into this, let me know if I can provide you with any additional information.

Btw, I realise this could very well be a rust compiler issue rather than a YCM issue.

[micbou]

I can't reproduce with the same version of Rust on macOS 10.13.4. Maybe the segfault is due to a lack of memory? Could you paste the full output of the build to see when the segfault occurs? You can specifically compile the Rust completer with the following command:

./install.py --skip-build --no-regex --rust-completer

[landersson]

Looking a bit closer, it's not the rust compiler that is crashing, but a binary called "build-script-build", built from "build.rs", and that I assume is part of the build process:

Rustc compiling "build-script-build":

Runningrustc --crate-name build_script_build build.rs --crate-type bin --emit=dep-info,link -C opt-level=3 -C metadata=575086e0e3f82a44 -C extra-filename=-575086e0e3f82a44 --out-dir /Users/larsandersson/dot-files/vim/vim/bundle/YouCompleteMe/third_party/ycmd/third_party/racerd/target/release/build/libracerd-575086e0e3f82a44 -L dependency=/Users/larsandersson/dot-files/vim/vim/bundle/YouCompleteMe/third_party/ycmd/third_party/racerd/target/release/deps --extern serde_codegen=/Users/larsandersson/dot-files/vim/vim/bundle/YouCompleteMe/third_party/ycmd/third_party/racerd/target/release/deps/libserde_codegen-c190851d0098ff18.rlib

Segfault when "build-script-build" is being run:

Running/Users/larsandersson/dot-files/vim/vim/bundle/YouCompleteMe/third_party/ycmd/third_party/racerd/target/release/build/libracerd-575086e0e3f82a44/build-script-builderror: failed to run custom build command forlibracerd v0.3.3 (file:///Users/larsandersson/dot-files/vim/vim/bundle/YouCompleteMe/third_party/ycmd/third_party/racerd)process didn't exit successfully:/Users/larsandersson/dot-files/vim/vim/bundle/YouCompleteMe/third_party/ycmd/third_party/racerd/target/release/build/libracerd-575086e0e3f82a44/build-script-build` (signal: 11, SIGSEGV: invalid memory reference)

[micbou]

I suppose this line is causing the segfault. When building the Rust completer, the script is actually moving to the directory YouCompleteMe/third_party/ycmd/third_party/racerd and running the command

cargo build --release

Do you still get the segfault if you build racerd without the --release flag? By the way, could you paste the output of cargo --version and rustc --version?

[landersson]

No segfault when building without --release. The whole build finishes successfully.

racerd:>rustc --version
rustc 1.26.0 (a77568041 2018-05-07)

cargo --version
cargo 1.26.0 (0e7c5a931 2018-04-06)

[micbou]

This may be related to issue rust-lang/rust#50586. Could you try with Rust 1.25.0?

[landersson]

You're probably right, it works with rust 1.25.0. That solves the issue for me. Thanks.

[micbou]

Closing as a Rust compiler issue then.