Miri fails to link on macOS

[RalfJung]

This night's CI run failed to link Miri on macOS:

  error: linking with `cc` failed: exit status: 1
    |
    = note:  "cc" "/Users/runner/work/miri/miri/target/release/deps/rustcCp3SzC/symbols.o" "<16 object files omitted>" "/Users/runner/work/miri/miri/target/release/deps/{libmiri-0677808f025590dc,libaes-09e9d28c6ff4e98b,libcipher-07a879939bb84157,libinout-9ac07fa210cb8e8c,libcrypto_common-20ba2c3c80de0c89,libgeneric_array-432515fad90ae2ef,libtypenum-1f710b46457a63cc,libdirectories-c8e97ef209ac03af,libdirs_sys-909fbb2d6ef5185a,liboption_ext-7ead06511e0a254d,liblibloading-eb30554de28b3c77,libmeasureme-361e730f14549109,librustc_hash-c691ea9089be4205,libparking_lot-ebbed55e476daba1,libparking_lot_core-7d42a1ba18cafe2b,liblock_api-044a4f7caf355672,libscopeguard-fe793b17e7b3ca9e,liblog-92cbfc272ac8f9f0,libchrono_tz-e7ec4315ddf96974,libphf-1c35e792ebb9c414,libphf_shared-9f1941949bec3b96,libsiphasher-b83ec05d6d146e9b,libchrono-1af576c490678ec0,libnum_traits-e195e779fdf5a3ad,libbitflags-c72cdb211a1a83d8,libserde-d33bf4120f04e612,libserde_core-7b485bd76c4c1521,liblibffi-c6363f8ec6cd29ac,liblibffi_sys-e1f822e8c8685318,libsmallvec-05f0212d13fce8ec,librand-aa6380c038c05e67,librand_chacha-d87eb525ac29daf0,libppv_lite86-798108eb2ef2c8b9,libzerocopy-a39d6e312cb19425,librand_core-d8ba3bb4449881d2,libgetrandom-38e7798d8a95fbc5,liblibc-c34cd58bbb393d67,libcfg_if-330c2477450fb8d5}.rlib" "<sysroot>/lib/rustlib/aarch64-apple-darwin/lib/librustc_driver-eb4552398d5d4c71.dylib" "<sysroot>/lib/rustlib/aarch64-apple-darwin/lib/libcompiler_builtins-*.rlib" "-liconv" "-lSystem" "-lSystem" "-lobjc" "-framework" "Foundation" "-lz" "-lLLVM-22-rust-1.95.0-nightly" "-lc++" "-liconv" "-lSystem" "-lc" "-lm" "-arch" "arm64" "-mmacosx-version-min=11.0.0" "-L" "/Users/runner/work/miri/miri/target/release/build/libffi-sys-b56f92500885a956/out/libffi-root/lib" "-L" "/Users/runner/work/miri/miri/target/release/build/libffi-sys-b56f92500885a956/out/libffi-root/lib32" "-L" "/Users/runner/work/miri/miri/target/release/build/libffi-sys-b56f92500885a956/out/libffi-root/lib64" "-o" "/Users/runner/work/miri/miri/target/release/deps/miri-eaa686b4b74c7c12" "-Wl,-dead_strip" "-nodefaultlibs" "-Wl,-rpath,<sysroot>/lib/rustlib/aarch64-apple-darwin/lib"
    = note: some arguments are omitted. use `--verbose` to show all linker arguments
    = note: ld: warning: ignoring duplicate libraries: '-lSystem', '-liconv'
            ld: warning: search path '/Users/runner/work/miri/miri/target/release/build/libffi-sys-b56f92500885a956/out/libffi-root/lib32' not found
            ld: warning: search path '/Users/runner/work/miri/miri/target/release/build/libffi-sys-b56f92500885a956/out/libffi-root/lib64' not found
            ld: library 'LLVM-22-rust-1.95.0-nightly' not found
            clang: error: linker command failed with exit code 1 (use -v to see invocation)

I so far have no clear idea for what changed where to cause this. @rust-lang/clippy is Clippy affected as well or do out-of-tree builds still work for you?

If the problem is caused by a rustc change, it's in this commit range: b3869b9...859951e.
My best guess is c033de9 which changed how LLVM is linked on the macOS dist builder which maybe could cause problems of this sort? No idea. That commit is part of #152768; Cc @ZuseZ4

Also Cc @bjorn3 for some more linker knowledge and @nikic since the error mentions LLVM.

[RalfJung]

I bisected it down to a single rustc PR: #153026. This is the one that includes that macOS dist builder change.

[nikic]

See #121889 for context on this error and

rust/src/bootstrap/src/core/build_steps/dist.rs

Line 2424 in 11ad63a

// Otherwise, replace the symlink with an equivalent linker script. This is used when

for how it was fixed.

It sounds like that fix doesn't work on macOS.