I'm familiar. Thanks. Bug report filed. FB25065811

@Etresoft You asked for it. $ sudo rm -rf /Library/Developer/CommandLineTools/ $ xcode-select --install xcode-select: note: install requested for command line developer tools $ xcode-select -p /Library/Developer/CommandLineTools Joeys-MacBook-Pro:~$ clang -v Apple clang version 21.0.0 (clang-2100.1.1.101) Target: arm64-apple-darwin25.6.0 Thread model: posix InstalledDir: /Library/Developer/CommandLineTools/usr/bin $ ld -v @(#)PROGRAM:ld PROJECT:ld-1267 BUILD 16:38:58 Jun 8 2026 configured to support archs: armv6 armv7 armv7s arm64 arm64e arm64_32 i386 x86_64 x86_64h armv6m armv7k armv7m armv7em armv8m.main armv8.1m.main will use ld-classic for: armv6 armv7 armv7s i386 armv6m armv7k armv7m armv7em LTO support using: LLVM version 21.0.0 (static support for 30, runtime is 30) TAPI support using: Apple TAPI version 21.0.0 (tapi-2100.0.2.6) $ vim test.c $ cat test.c #include <stdio.h> int main(void) { printf("Hello world!\n"); return 0; } $ clang test.c ld: tapi error: malformed file /Library/Developer/CommandLineTools/SDKs/MacOSX27.0.sdk/usr/lib/libSystem.B.tbd:4:20: error: unknown architecture arm64e.x1-macos, arm64e.x1-maccatalyst ] ^~~~~~~~~~~~~~~ in '/Library/Developer/CommandLineTools/SDKs/MacOSX27.0.sdk/usr/lib/libSystem.tbd' clang: error: linker command failed with exit code 1 (use -v to see invocation)