Mac Catalyst: `ld` is trying to find prebuilt `rustlib` when building with `-Z build-std`

[imWildCat]

I tried this code:

fn main() {
    println!("Hello, world!");
}

with cargo +nightly build --verbose -Z build-std --target x86_64-apple-ios-macabi

source: https://github.com/imWildCat-archived/rs-demo/blob/main/src/main.rs

I expected to see this happen: this code can be built with cargo, with nightly toolchain, targeting x86_64-apple-ios-macabi

Instead, this happened:

Compiling rs-demo v0.1.0 (/Users/runner/work/rs-demo/rs-demo)
...
...
= note: ld: warning: directory not found for option '-L/Users/runner/.rustup/toolchains/nightly-x86_64-apple-darwin/lib/rustlib/x86_64-apple-ios-macabi/lib'
[80](https://github.com/imWildCat-archived/rs-demo/actions/runs/4092406201/jobs/7057120479#step:6:81)
          ld: warning: directory not found for option '-L/Users/runner/.rustup/toolchains/nightly-x86_64-apple-darwin/lib/rustlib/x86_64-apple-ios-macabi/lib'
[81](https://github.com/imWildCat-archived/rs-demo/actions/runs/4092406201/jobs/7057120479#step:6:82)
          ld: building for Mac Catalyst, but linking in object file built for , file '/Users/runner/work/rs-demo/rs-demo/target/x86_64-apple-ios-macabi/debug/deps/rs_demo-521d12542c4c7be3.184v2gvf82jr0rex.rcgu.o'
[82](https://github.com/imWildCat-archived/rs-demo/actions/runs/4092406201/jobs/7057120479#step:6:83)
          clang: error: linker command failed with exit code 1 (use -v to see invocation)
[83](https://github.com/imWildCat-archived/rs-demo/actions/runs/4092406201/jobs/7057120479#step:6:84)
          
[84](https://github.com/imWildCat-archived/rs-demo/actions/runs/4092406201/jobs/7057120479#step:6:85)

[85](https://github.com/imWildCat-archived/rs-demo/actions/runs/4092406201/jobs/7057120479#step:6:86)
error: could not compile `rs-demo` due to previous error
[86](https://github.com/imWildCat-archived/rs-demo/actions/runs/4092406201/jobs/7057120479#step:6:87)

[87](https://github.com/imWildCat-archived/rs-demo/actions/runs/4092406201/jobs/7057120479#step:6:88)
Caused by:
[88](https://github.com/imWildCat-archived/rs-demo/actions/runs/4092406201/jobs/7057120479#step:6:89)
  process didn't exit successfully: `rustc --crate-name rs_demo --edition=2021 src/main.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --crate-type bin --emit=dep-info,link -C embed-bitcode=no -C split-debuginfo=unpacked -C debuginfo=2 -C metadata=521d12542c4c7be3 -C extra-filename=-521d12542c4c7be3 --out-dir /Users/runner/work/rs-demo/rs-demo/target/x86_64-apple-ios-macabi/debug/deps --target x86_64-apple-ios-macabi -C incremental=/Users/runner/work/rs-demo/rs-demo/target/x86_64-apple-ios-macabi/debug/incremental -L dependency=/Users/runner/work/rs-demo/rs-demo/target/x86_64-apple-ios-macabi/debug/deps -L dependency=/Users/runner/work/rs-demo/rs-demo/target/debug/deps --extern 'noprelude:alloc=/Users/runner/work/rs-demo/rs-demo/target/x86_64-apple-ios-macabi/debug/deps/liballoc-9c4e6a45fc1dc0a3.rlib' --extern 'noprelude:compiler_builtins=/Users/runner/work/rs-demo/rs-demo/target/x86_64-apple-ios-macabi/debug/deps/libcompiler_builtins-7d186f938ad1e774.rlib' --extern 'noprelude:core=/Users/runner/work/rs-demo/rs-demo/target/x86_64-apple-ios-macabi/debug/deps/libcore-339a72cfd77df96f.rlib' --extern 'noprelude:panic_unwind=/Users/runner/work/rs-demo/rs-demo/target/x86_64-apple-ios-macabi/debug/deps/libpanic_unwind-06c139a128f5078d.rlib' --extern 'noprelude:proc_macro=/Users/runner/work/rs-demo/rs-demo/target/x86_64-apple-ios-macabi/debug/deps/libproc_macro-b6089ec1e1d5f8a1.rlib' --extern 'noprelude:std=/Users/runner/work/rs-demo/rs-demo/target/x86_64-apple-ios-macabi/debug/deps/libstd-a6b8e5f053fdec98.rlib' -Z unstable-options` (exit status: 1)

Meta

rustc --version --verbose:

rustc 1.67.0 (fc594f156 2023-01-24)
binary: rustc
commit-hash: fc594f15669680fa70d255faec3ca3fb507c3405
commit-date: 2023-01-24
host: x86_64-apple-darwin
release: 1.67.0
LLVM version: 15.0.6

(source)

Nightly version:

rustc 1.69.0-nightly (658fad6c5 2023-02-03)

Full repro: https://github.com/imWildCat-archived/rs-demo/actions/runs/4092406201/jobs/7057120479

Additional notes

This bug has been existing since last summer, probably before +nightly-2022-08-08.
Previously I thought it is related to #106925
But it should be a different issue.

I'm happy to propose a fix. However, I'm not sure where I can start. May I have some hint?

[bjorn3]

The thing described by the issue title is merely a warning. The actual error is building for Mac Catalyst, but linking in object file built for , file '/Users/runner/work/rs-demo/rs-demo/target/x86_64-apple-ios-macabi/debug/deps/rs_demo-521d12542c4c7be3.184v2gvf82jr0rex.rcgu.o. What does file /Users/runner/work/rs-demo/rs-demo/target/x86_64-apple-ios-macabi/debug/deps/rs_demo-521d12542c4c7be3.184v2gvf82jr0rex.rcgu.o show?

[imWildCat]

Thanks for helping!

@bjorn3 I made another commit to my demo: https://github.com/imWildCat-archived/rs-demo/actions/runs/4110334750

which created artifacts for target dir.

-rwxr-xr-x@ 1 wildcat  staff   3.0K Feb  7  2023 rs_demo-521d12542c4c7be3.11h1k1cxazyrm761.rcgu.o
-rwxr-xr-x@ 1 wildcat  staff   6.5K Feb  7  2023 rs_demo-521d12542c4c7be3.1b4n3ypj1i7wdx18.rcgu.o
-rwxr-xr-x@ 1 wildcat  staff   2.7K Feb  7  2023 rs_demo-521d12542c4c7be3.1bxeufcsx2uf9wms.rcgu.o
-rwxr-xr-x@ 1 wildcat  staff   3.2K Feb  7  2023 rs_demo-521d12542c4c7be3.2n8jw0mkj0otg1qk.rcgu.o
-rwxr-xr-x@ 1 wildcat  staff   2.7K Feb  7  2023 rs_demo-521d12542c4c7be3.2qji0k665nmkk6cb.rcgu.o
-rwxr-xr-x@ 1 wildcat  staff   4.8K Feb  7  2023 rs_demo-521d12542c4c7be3.3a98xjqypw74yju3.rcgu.o
-rwxr-xr-x@ 1 wildcat  staff   4.6K Feb  7  2023 rs_demo-521d12542c4c7be3.3i3usuytvnh90f5d.rcgu.o
-rwxr-xr-x@ 1 wildcat  staff   1.6K Feb  7  2023 rs_demo-521d12542c4c7be3.3okfkjsnslejtqlm.rcgu.o
-rwxr-xr-x@ 1 wildcat  staff   247B Feb  7  2023 rs_demo-521d12542c4c7be3.d

➜  rust-target-dir-x86_64-apple-ios-macabi cd x86_64-apple-ios-macabi/debug/deps/

➜  deps fd rs_demo-521d12542c4c7be3. -x file {}
./rs_demo-521d12542c4c7be3.3i3usuytvnh90f5d.rcgu.o: Mach-O 64-bit object x86_64
./rs_demo-521d12542c4c7be3.2qji0k665nmkk6cb.rcgu.o: Mach-O 64-bit object x86_64
./rs_demo-521d12542c4c7be3.3okfkjsnslejtqlm.rcgu.o: Mach-O 64-bit object x86_64
./rs_demo-521d12542c4c7be3.1bxeufcsx2uf9wms.rcgu.o: Mach-O 64-bit object x86_64
./rs_demo-521d12542c4c7be3.3a98xjqypw74yju3.rcgu.o: Mach-O 64-bit object x86_64
./rs_demo-521d12542c4c7be3.11h1k1cxazyrm761.rcgu.o: Mach-O 64-bit object x86_64
./rs_demo-521d12542c4c7be3.2n8jw0mkj0otg1qk.rcgu.o: Mach-O 64-bit object x86_64
./rs_demo-521d12542c4c7be3.1b4n3ypj1i7wdx18.rcgu.o: Mach-O 64-bit object x86_64
./rs_demo-521d12542c4c7be3.d: ASCII text

[bjorn3]

That CI run complains about ld: building for Mac Catalyst, but linking in object file built for , file '/var/folders/24/8k48jl6d249_n_qfxwsl6xvm0000gn/T/rustcIrdx0v/symbols.o' for architecture x86_64 which is an object file produced by the object crate rather than LLVM. @philipc I think a LC_BUILD_VERSION command needs to be emitted by the object crate with the right target platform for the linker to accept object files when compiling for Mac Catalyst. There seems to be a special case where for all platforms except Mac Catalyst an unknown platform is accepted too: https://github.com/apple-oss-distributions/ld64/blob/dbf8f7feb5579761f1623b004bd468bdea7c6225/src/ld/PlatformSupport.cpp#L82-L83

[imWildCat]

Thanks! I think we can dedup?

Found a similar one: #106021

cc @thomcc

[bjorn3]

Yeah, that looks like it is the same issue.

[imWildCat]

@bjorn3 thanks! let me try the fix proposed by @ara4n first

[imWildCat]

This is really difficult for me. I decided to give up my Mac Catalyst app first. 🥶
I don't think the community should waste time following up on Apple's strange changes anymore. Because almost no one uses Rust to develop Mac Catalyst apps anymore.

[munhitsu]

I've used automerge 1.0 with a Catalyst app. Now when automerge 2.0 was released I can't migrate because of this bug.

[imWildCat]

@munhitsu #106021