Feedback when using with rustc/bazel/rules_rust

[bgeron]

Hi,

Just wanted to give some feedback. I'm evaluating sold for rustc/bazel/rules_rust, but I cannot find a working way to use it.

• If I specify -C linker=ld64.mold (via --@rules_rust//:extra_rustc_flag=), then rustc generates linker argument -m64 which mold does not understand.
• If I specify -C linker=mold, then rustc additionally generates -arch x86_64 which mold does not understand.
• I played around with various values of -C linker-flavor, but none seem to generate better args for mold. In particular, the lld flavors don't work because rustc will specify -flavor.
• By default, rustc adds -dead_strip or -Wl,-dead_strip, which would be nice to retain.

Rustc when invoked with cargo seems to work fine somehow. I don't know if the differences are in Bazel or in our project configuration, which is quite elaborate because we're cross-compiling for ios.

Cheers, Bram

[rui314]

The linker should be invoked indirectly by the compiler, so the linker should be the default (which is cc or c++).

Does passing -C link-arg=-fuse-ld=/path/to/ld64.sold work?

[bgeron]

That seems to work, thanks! I don't even have to disable dead code stripping any more.