Latest nightly crashes on centos 5

[konstin]

This can be reproduced in a centos 5 docker container, such as the one provided by python's pypa:

docker run -it quay.io/pypa/manylinux1_x86_64 bash

curl https://sh.rustup.rs -sSf | sh -s -- -y --default-toolchain nightly
source $HOME/.cargo/env
rustup toolchain add stable
cargo new hello-world
cd hello-world
cargo +stable build # This works
cargo build # This crashes

The last command produces the following error:

error: process didn't exit successfully: `rustc -vV` (exit code: 1)
--- stdout
rustc 1.33.0-nightly (96d1334e5 2018-12-14)
binary: rustc
commit-hash: 96d1334e567237b1507cd277938e7ae2de75ff51
commit-date: 2018-12-14
host: x86_64-unknown-linux-gnu
release: 1.33.0-nightly

--- stderr
error: couldn't load codegen backend "/root/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/codegen-backends/librustc_codegen_llvm-llvm.so": "/lib64/libgcc_s.so.1: version `GCC_4.3.0\' not found (required by /root/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/codegen-backends/librustc_codegen_llvm-llvm.so)"

Versions:

cat /etc/redhat-release: CentOS release 5.11 (Final)
cargo -V: cargo 1.33.0-nightly (2cf1f5dda 2018-12-11)
rustc -V: rustc 1.33.0-nightly (96d1334e5 2018-12-14)
rustc -vV: crashes with the same output as above

[alexcrichton]

Some bisection reveals that this is a regression from #56051 actually, and I suspect the most likely candidate of that rollup is #55952

cc @michaelwoerister

As to why these symbols are just now showing up, I'm not sure...

[alexcrichton]

Ok I've confirmed #55952 is the cause of this bug. I don't really know how this is showing up though as none of the symbols which use GCC_4.3.0 are even referenced from the file:

$ readelf -s obj/build/x86_64-unknown-linux-gnu/llvm/bin/llc | grep GCC_4.3.0
   343: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __floatuntitf@GCC_4.3.0 (12)
   344: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __netf2@GCC_4.3.0 (12)
   346: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __floatunditf@GCC_4.3.0 (12)
   347: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __multf3@GCC_4.3.0 (12)
   350: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __fixtfdi@GCC_4.3.0 (12)
   351: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __eqtf2@GCC_4.3.0 (12)
   353: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __powitf2@GCC_4.3.0 (12)
   354: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __floatunsitf@GCC_4.3.0 (12)
   355: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __floatditf@GCC_4.3.0 (12)
   356: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __fixtfti@GCC_4.3.0 (12)
   357: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __lttf2@GCC_4.3.0 (12)
   358: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __extendsftf2@GCC_4.3.0 (12)
   361: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __letf2@GCC_4.3.0 (12)
   363: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __extenddftf2@GCC_4.3.0 (12)
   365: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __fixunstfti@GCC_4.3.0 (12)
   367: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __fixtfsi@GCC_4.3.0 (12)
   370: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __gttf2@GCC_4.3.0 (12)
   371: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __addtf3@GCC_4.3.0 (12)
   374: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __divtf3@GCC_4.3.0 (12)
   377: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __extendxftf2@GCC_4.3.0 (12)
   378: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __trunctfdf2@GCC_4.3.0 (12)
   382: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __trunctfxf2@GCC_4.3.0 (12)
   383: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __fixunstfdi@GCC_4.3.0 (12)
   385: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __unordtf2@GCC_4.3.0 (12)
   389: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __getf2@GCC_4.3.0 (12)
   390: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __fixunstfsi@GCC_4.3.0 (12)
   391: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __floattitf@GCC_4.3.0 (12)
   394: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __floatsitf@GCC_4.3.0 (12)
   395: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __subtf3@GCC_4.3.0 (12)
   396: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __trunctfsf2@GCC_4.3.0 (12)

None of those symbols are even used from llc or LLVM or... anywhere it seems. I have no idea what's putting that into some symbol table that needs to be resolved.

This may be some LLD change though because if I disable ThinLTO for LLVM itself then these symbol references seem to go away...

[alexcrichton]

Ok I've bisected this to rust-lang/lld@103b4dc, which makes sense sort of because that's injecting references to all builtins, even if we're not actually using them.

I'll follow up with LLVM later tomorrow

[alexcrichton]

Or actually, I've gone ahead and opened an upstream bug report to get the ball rolling there.

This is also a beta regression as well, so I'm retagging as such.

I believe the only solution we have for now on this is to turn off ThinLTO, so I'm going to send a PR to do that.

[alexcrichton]

Er turns out this is likely already fixed at llvm-mirror/lld@3be4e82, so I can try out building that locally