How to pass -fno-sanitize=undefined to zig cc?

[jiacai2050]

Since zig cc pass -fsanitize=undefined -fsanitize-trap=undefined by default, some project can be built successfully, but
will throw error when running

$ ./target/debug/foo
Illegal instruction

cargo-zigbuild/src/zig.rs

Line 510 in 871605b

if let Ok(mut options) = Self::collect_zig_cc_options(&zig_wrapper, raw_target) {

After some research, it seems there is no way to pass zig cc options?

• Ref: https://nathancraddock.com/blog/zig-cc-undefined-behavior/

[messense]

Try pass it in CFLAGS, CXXFLAGS and/or RUSTFLAGS.

[messense]

• For RUSTFLAGS you probably need to pass it in -C link-arg since -f isn't a rustc option, and target specific RUSTFLAGS might be required.
• For CFLAGS/CXXFLAGS you probably need to pass it in target specific env var (for example CFLAGS_<target triple>) since you're cross compilng, you don't want to pass it to build scripts.

[jiacai2050]

RUSTFLAGS is used for rustc, so I don't think it's the way to go.

It's more likely to be CFLAGS or CXXFLAGS, and I don't use zigbuild for cross compile, just normal build, since my host has old version gcc installed, and my project require newer one.

[messense]

I don't use zigbuild for cross compile, just normal build

It's complicated when build scripts are involved, it's not-so-normal per se.

See

• https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#target-applies-to-host
• Cross compilation is broken when host and target architectures are the same. PyO3/pyo3#1513

[jiacai2050]

I can't imagine the issue is so complex.

$ cat ~/bin/zigcpp

zig c++ -fno-sanitize=undefined $@

$ cat ~/bin/zigcc

zig cc -fno-sanitize=undefined $@

$ CC=zigcc CXX=zigcpp zig build

I try build like this, it builds and run successfully.

Since my use case is so simple that I can just use this original solution.

Thanks for your help.

[jiacai2050]

FYI, also we need to set linker explicitly like this:

[target.x86_64-unknown-linux-gnu]
linker = "zigcc"