CI: Update Xcode version

[ehuss]

In #120914 we downgraded Xcode from 15 to 14 due to two issues:

• invalid r_symbolnum when testing cranelift
• cmake fails to verify that clang can build a simple test program.

We will need to upgrade eventually since GitHub removes older xcode versions over time. My rough estimate is that we probably have about a year before that happens. I think it would be good to be prepared. There is also the possibility that GitHub will drop the x86_64 macos runners, in which case this will be moot.

I tested Xcode 15, but that still had the same problems.

Discussion that led up to this: https://rust-lang.zulipchat.com/#narrow/stream/242791-t-infra/topic/Weird.20CI.20failure.20on.20x86_64-apple-1.3A.20invalid.20r_symbolnum.3D14

Cmake error

The cmake error looks like this:

-- Check for working C compiler: /Users/runner/work/rust/rust/clang+llvm-14.0.5-x86_64-apple-darwin/bin/clang - broken
  The C compiler

    "/Users/runner/work/rust/rust/clang+llvm-14.0.5-x86_64-apple-darwin/bin/clang"

  is not able to compile a simple test program.

  It fails with the following output:

    Change Dir: '/Users/runner/work/rust/rust/build/x86_64-apple-ios/native/sanitizers/build/CMakeFiles/CMakeScratch/TryCompile-DlTLuP'
    
    Run Build Command(s): /usr/local/bin/ninja -v cmTC_4a181
    [1/2] /Users/runner/work/rust/rust/clang+llvm-14.0.5-x86_64-apple-darwin/bin/clang --target=x86_64-apple-ios   -fPIC --target=x86_64-apple-ios -m64 -mios-simulator-version-min=7.0 -isysroot /Applications/Xcode_15.0.1.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.0.sdk -fembed-bitcode -fdebug-prefix-map=/Users/runner/work/rust/rust=/rustc/llvm -fembed-bitcode=off -MD -MT CMakeFiles/cmTC_4a181.dir/testCCompiler.c.o -MF CMakeFiles/cmTC_4a181.dir/testCCompiler.c.o.d -o CMakeFiles/cmTC_4a181.dir/testCCompiler.c.o -c /Users/runner/work/rust/rust/build/x86_64-apple-ios/native/sanitizers/build/CMakeFiles/CMakeScratch/TryCompile-DlTLuP/testCCompiler.c
    [2/2] : && /Users/runner/work/rust/rust/clang+llvm-14.0.5-x86_64-apple-darwin/bin/clang --target=x86_64-apple-ios -fPIC --target=x86_64-apple-ios -m64 -mios-simulator-version-min=7.0 -isysroot /Applications/Xcode_15.0.1.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.0.sdk -fembed-bitcode -fdebug-prefix-map=/Users/runner/work/rust/rust=/rustc/llvm -fembed-bitcode=off -Wl,-search_paths_first  -static-libstdc++ CMakeFiles/cmTC_4a181.dir/testCCompiler.c.o -o cmTC_4a181   && :
    FAILED: cmTC_4a181 
    : && /Users/runner/work/rust/rust/clang+llvm-14.0.5-x86_64-apple-darwin/bin/clang --target=x86_64-apple-ios -fPIC --target=x86_64-apple-ios -m64 -mios-simulator-version-min=7.0 -isysroot /Applications/Xcode_15.0.1.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.0.sdk -fembed-bitcode -fdebug-prefix-map=/Users/runner/work/rust/rust=/rustc/llvm -fembed-bitcode=off -Wl,-search_paths_first  -static-libstdc++ CMakeFiles/cmTC_4a181.dir/testCCompiler.c.o -o cmTC_4a181   && :
    clang-14: warning: argument unused during compilation: '-static-libstdc++' [-Wunused-command-line-argument]
    ld: unknown options: -ios_simulator_version_min 
    clang-14: error: linker command failed with exit code 1 (use -v to see invocation)
    ninja: build stopped: subcommand failed.

  CMake will not be able to correctly generate this project.
Call Stack (most recent call first):
  CMakeLists.txt:14 (project)

One workaround is to set USE_XCODE_CLANG: 1 in ci.yml. I'm not sure if there is a strong reason to use USE_XCODE_CLANG or not. Another possibility is to update the pre-built clang to match the version in Xcode and see if that helps. My guess is that having clang and ld out of sync might contribute to the problem.

[bjorn3]

rust-lang/rustc_codegen_cranelift#1456 when testing cranelift

#127162 will fix this.

[ehuss]

#131494 points out that removal of xcode 14 is imminent via actions/runner-images#10703.