CMake build fails on macOS Sequoia with Xcode 16 release version

[ADKaster]

Description

Cloning the repo with Xcode 16 selected and CMake 3.30.3 fails to build using the following steps:

cmake -B build -GNinja
ninja -C build

Xcode Version 16.0 (16A242d)

swift-driver version: 1.115 Apple Swift version 6.0 (swiftlang-6.0.0.9.10 clang-1600.0.26.2)
Target: arm64-apple-macosx15.0

cmake version 3.30.3

ninja version: 1.12.1

The build fails in the same way on both:

main: 47b127f1c98a9f4ff593288c7ee0c6618a912e6b
release/6.0.2: 3755346b1da0f611d3a8bd531831ac48c126b9d4

Expected behavior

Same build as swift build is produced

Actual behavior

Backtrace in the linked gist below

https://gist.github.com/ADKaster/8c62194d219a6f6599c2409d24e304e4

It appears to be a problem with swift-syntax?

1.	Apple Swift version 6.0 (swiftlang-6.0.0.9.10 clang-1600.0.26.2)
2.	Compiling with effective version 5.10
3.	While evaluating request ExecuteSILPipelineRequest(Run pipelines { Non-Diagnostic Mandatory Optimizations, Serialization, Rest of Onone } on SIL for TestingMacros)
4.	While running pass swiftlang/swift-testing#396 SILFunctionTransform "OwnershipModelEliminator" on SILFunction "@$s11SwiftSyntax9TokenKindO2eeoiySbAC_ACtFZ".
 for '==(_:_:)' (in module 'SwiftSyntax')

Steps to reproduce

git clone
cd swift-testing
cmake -B build -GNinja
cmake --build build

swift-testing version/commit hash

47b127f1c98a9f4ff593288c7ee0c6618a912e6b

Swift & OS version (output of swift --version ; uname -a)

swift-driver version: 1.115 Apple Swift version 6.0 (swiftlang-6.0.0.9.10 clang-1600.0.26.2)
Target: arm64-apple-macosx15.0
Darwin Andrews-MacBook-Pro.local 24.0.0 Darwin Kernel Version 24.0.0: Mon Aug 12 20:52:12 PDT 2024; root:xnu-11215.1.10~2/RELEASE_ARM64_T6020 arm64

[ADKaster]

Also fails with Xcode 16.1 Beta 2

swift-driver version: 1.115 Apple Swift version 6.0 (swiftlang-6.0.0.9.11 clang-1600.0.26.2)
Target: arm64-apple-macosx15.0

Xcode Version 16.1 beta 2 (16B5014f)

[stmontgomery]

Do you get a different result if you first revert the change in swiftlang/swift-testing#690?

[grynspan]

What's your thinking Stuart?

[ADKaster]

@stmontgomery Yes, applying this diff on top of 47b127f1c98a9f4ff593288c7ee0c6618a912e6b allows the build to complete

diff --git a/Sources/TestingMacros/CMakeLists.txt b/Sources/TestingMacros/CMakeLists.txt
index c916204..bb55f09 100644
--- a/Sources/TestingMacros/CMakeLists.txt
+++ b/Sources/TestingMacros/CMakeLists.txt
@@ -31,8 +31,8 @@ if(SwiftTesting_BuildMacrosAsExecutables)
   set(FETCHCONTENT_BASE_DIR ${CMAKE_BINARY_DIR}/_d)
   FetchContent_Declare(SwiftSyntax
     GIT_REPOSITORY https://github.com/swiftlang/swift-syntax
-    GIT_TAG cb53fa1bd3219b0b23ded7dfdd3b2baff266fd25) # 600.0.0
-  FetchContent_MakeAvailable(SwiftSyntax)
+    GIT_TAG 27b74edd5de625d0e399869a5af08f1501af8837)
+FetchContent_MakeAvailable(SwiftSyntax)
 endif()

Edit: Double checked, 47b127f1 definitely still fails unaltered, and works with the diff applied when using Xcode 16.1 Beta 2

swift-driver version: 1.115 Apple Swift version 6.0 (swiftlang-6.0.0.9.11 clang-1600.0.26.2)
Target: arm64-apple-macosx15.0

[grynspan]

Sounds like a compiler bug that's conflicting with the 600.0.0 tag. We aren't seeing the compiler issue with the latest main-branch toolchain (our CI is happy.) We should send this over to the Swift repo for triage, I think.

[ChaseKnowlden]

Failed to build for me as well.

[ADKaster]

I did see some interesting compiler warnings (visible in my gist in the initial post) about experimental features not being enabled as expected, so it could be some CMake flag trickery with the swift-testing repo and the imported swift-syntax target is causing conflicts that cause an unsupported configuration to be built.

[stmontgomery]

Thanks for those data points @ADKaster! Over to the swift repo to investigate the build failure further.

CC @ahoppen @bnbarham for visibility

[stmontgomery]

I did see some interesting compiler warnings (visible in my gist in the initial post) about experimental features not being enabled as expected

That's interesting to note. Here are those warnings pulled out for convenience:

<unknown>:0: warning: ignoring -experimental-skip-non-inlinable-function-bodies-without-types (overriden by -experimental-allow-non-resilient-access)
<unknown>:0: warning: ignoring -experimental-allow-non-resilient-access (overriden by -compile-module-from-interface or -typecheck-module-from-interface)
<unknown>:0: warning: ignoring -experimental-package-cmo (requires -experimental-allow-non-resilient-access)
<unknown>:0: warning: ignoring -experimental-allow-non-resilient-access (overriden by -compile-module-from-interface or -typecheck-module-from-interface)
<unknown>:0: warning: ignoring -experimental-package-cmo (requires -experimental-allow-non-resilient-access)

[rintaro]

This should resolve the issue: swiftlang/swift-syntax#2872
But swift-testing would need to update the reference here https://github.com/swiftlang/swift-testing/blob/83b0b049d6f73b58e05c0e3f1864c9b1db8b07b0/Sources/TestingMacros/CMakeLists.txt#L34