build-toolchain script fails on M1 Mac with .../swift-macosx-arm64/bin/swiftc: No such file or directory

[allevato]

When running utils/build-toolchain on an M1 Mac, the build fails when compiling Swift modules with the following error:

FAILED: SwiftCompilerSources/_CompilerRegexParser.o /Users/allevato/Source/Swift/build/buildbot_osx/swift-macosx-arm64/SwiftCompilerSources/_CompilerRegexParser.o
cd /Users/allevato/Source/Swift/swift/SwiftCompilerSources && /Users/allevato/Source/Swift/build/buildbot_osx/swift-macosx-arm64/bin/swiftc -c <additional compiler args...>
/bin/sh: /Users/allevato/Source/Swift/build/buildbot_osx/swift-macosx-arm64/bin/swiftc: No such file or directory

Indeed, the only binaries in that directory on my machine are the following:

$ ls /Users/allevato/Source/Swift/build/buildbot_osx/swift-macosx-arm64/bin/
lldb-check-expect lldb-with-tools

Additional discussion at https://forums.swift.org/t/get-the-error-when-building-the-toolchain/58665.

Steps To Reproduce

Steps to reproduce the behavior:

1. Run utils/build-toolchain $TOOLCHAIN_ID (where TOOLCHAIN_ID is some arbitrary name)

Expected behavior

A toolchain is built.

Environment

• OS: macOS 12.4
• Xcode Version/Tag/Branch: Xcode 13.3; apple/swift main branch at HEAD

[CNKCQ]

I got the same error

[keith]

#60624