Incorrect RUSTFLAGS parsing

[lucab]

It looks like env_args() is blindly splitting env args on spaces, making -C link-args impossible to use.

This happens when trying to use multiple linker args:

$ rustc -C help | grep link-args
    -C         link-args=val -- extra arguments to pass to the linker (space separated)

$ RUSTFLAGS='-C link-args="-fPIE -pie -Wl,-z,relro -Wl,-z,now"' ./target/release/cargo build --verbose
error: failed to run `rustc` to learn about target-specific information

Caused by:
  process didn't exit successfully: `rustc - --crate-name _ --print=file-names -C link-args="-fPIE -pie -Wl,-z,relro -Wl,-z,now" --crate-type bin --crate-type rlib --target x86_64-unknown-linux-gnu` (exit code: 101)
--- stderr
error: Unrecognized option: 'p'.

Output above is from current master (0.15.0-pre).

[alexcrichton]

Thanks for the report! This is working as expected, however, as this is defined behavior of how RUSTFLAGS is parsed. You can work around this, however, with .cargo/config which supports spaces in paths.

[alexcrichton]

er, spaces, in arguments*

[lucab]

While I understand the dotfile feature, I'm a bit puzzled on the UX side of this.

How are scripts supposed to pass existing/dynamic environmental $LDFLAGS to cargo/rustc? Especially when those are inherited though makefile or similar automation tools, I can't envision doing dotfile manipulation all the times.

Is there any other way which doesn't require going back and forward through user files?

[alexcrichton]

In some sense $LDFLAGS is a bash-ism (or shell-ism), and Cargo isn't a shell, so interpretation is inevitable no matter what. With more recent versions of rustc you can split $LDFLAGS on spaces and pass each as -Clink-arg=$foo (note the link-arg, not link-args).

[lucab]

Thanks for the answer, that's indeed a good way forward! For readers from the future, recent here means >= 1.13.0.

With the answer at hand, it was easier finding references (which I'm dumping here for cross-linking):

• RFC: Add space-friendly arguments rfcs#1509
• PR: rustc: implement -C link-arg rust#36574
• Release notes: https://github.com/rust-lang/rust/blame/1.13.0/RELEASES.md#L18