[iOS/OSX] .bytecode.deflate files in static lib fail linking with `-ObjC`

[vhbit]

Static library produced by Rust can't be linked into OS X/iOS project if the final binary is built with -ObjC linker flag (which means quite often).

Example output:

ld: in ../target/i386-apple-ios/libsync-90e4806dd582adb4.a(r-compress-compress-1019ddeae8817539.0.bytecode.deflate), archive member 'r-compress-compress-1019ddeae8817539.0.bytecode.deflate' with length 29136 is not mach-o or llvm bitcode for architecture i386

Short description of flag:

This flag causes the linker to load every object file in the library that defines an Objective-C class or category. While this option will typically result in a larger executable (due to additional object code loaded into the application), it will allow the successful creation of effective Objective-C static libraries that contain categories on existing classes.

[vhbit]

@alexcrichton is it safe to drop .bytecode.deflate files at all in case of static lib?

[alexcrichton]

I'm pretty surprised that archives have bytecode in them, they definitely shouldn't!

[vhbit]

I've quickly checked rustc::link and rustc_back::archive and it seems it shouldn't be the case - archive adds to skip list the following construction format!("{}.bytecode.deflate", name") and the filename it generates is format!("r-{}-{}", name, filename). Considering reported filename (r-compress-compress-1019ddeae8817539.0.bytecode.deflate) doesn't match, may it be actually a cargo issue - as linker expects a name without a fingerprint in suffix?

[alexcrichton]

Ah I think that the compiler is taking -C metadata into account at some point erroneously, causing it to stick around in the archive and end up as the final filename you see.

[vhbit]

Great, can you provide me with a bit more information where else to check, I'd be glad to fix it tomorrow.

[alexcrichton]

I would suspect somewhere in rustc::back, I'd probably just grep around for bytecode.deflate and see if anything is accidentally taking -C extra-filename into account.