rustc 1.32 using system LLVM crashes while building the resvg crate

[RazrFalcon]

Initial issue: linebender/resvg#110

   Compiling resvg-capi v0.5.0 (/home/user/.cache/pikaur/build/resvg-git/src/resvg/capi)
error: Could not compile `resvg-capi`.

Caused by:
  process didn't exit successfully: `rustc --crate-name resvg capi/src/lib.rs --color always --crate-type cdylib --crate-type staticlib --emit=dep-info,link -C opt-level=3 -C lto --cfg 'feature="cairo-backend"' --cfg 'feature="cairo-sys-rs"' --cfg 'feature="glib"' --cfg 'feature="qt-backend"' --cfg 'feature="resvg"' -C metadata=34044ee5526873f1 --out-dir /home/user/.cache/pikaur/build/resvg-git/src/resvg/target/release/deps -L dependency=/home/user/.cache/pikaur/build/resvg-git/src/resvg/target/release/deps --extern cairo_sys=/home/user/.cache/pikaur/build/resvg-git/src/resvg/target/release/deps/libcairo_sys-a11059b04a916894.rlib --extern fern=/home/user/.cache/pikaur/build/resvg-git/src/resvg/target/release/deps/libfern-f758ae3d5f3ac504.rlib --extern glib=/home/user/.cache/pikaur/build/resvg-git/src/resvg/target/release/deps/libglib-42c67ca816dc468b.rlib --extern log=/home/user/.cache/pikaur/build/resvg-git/src/resvg/target/release/deps/liblog-4fed47ee5064f102.rlib --extern resvg=/home/user/.cache/pikaur/build/resvg-git/src/resvg/target/release/deps/libresvg-9bfdf02a73881248.rlib -L native=/home/user/.cache/pikaur/build/resvg-git/src/resvg/target/release/build/resvg-qt-529ad70e8602e985/out` (signal: 11, SIGSEGV: invalid memory reference)

Steps to reproduce:

sudo pacman -S rust
git clone https://github.com/RazrFalcon/resvg.git
cd resvg/capi
cargo build --release

The master branch can be built without rustc crashing on Gentoo and on Travis (Ubuntu 14.04.5 LTS).

UPD: I've tried to build it too and I have the same error. Looks like something wrong with the Arch's rustc. Because if we use the one installed via rustup - everything is ok.

UPD: it can be fixed by disabling the LTO, which is enabled by default for resvg.

[jonas-schievink]

Arch uses this build config for packaging fwiw:

[llvm]
link-shared = true

[build]
cargo = "/usr/bin/cargo"
rustc = "/usr/bin/rustc"
python = "python2.7"
extended = true
sanitizers = false

[install]
prefix = "/usr"

[rust]
# 0 or the new default of 16 is faster, but can result in worse performance
# https://github.com/rust-lang/rust/issues/47745
codegen-units = 1

debuginfo = true
debuginfo-lines = true

channel = "stable"

rpath = false

[target.x86_64-unknown-linux-gnu]
llvm-config = "/usr/bin/llvm-config"

[sfackler]

Arch's build uses the system LLVM, while rustup's uses a bundled one, so the problem is probably due to an LLVM bug that's only present in Arch's version.

[Centril]

Tentatively labeling as I-unsound due to "invalid memory reference".

[sfackler]

That's how LLVM asserts look when built without debug check enabled.

[nikic]

Could you please provide a backtrace for the segfault?

[RazrFalcon]

@nikic How can I do this?