Currently getting this when compiling on macOS Catalina beta 8 (build 19A558d) and Xcode 11 GM (build 11A419c), with latest checkout (using update-checkout --clone):
In file included from /Users/suyashsrijan/Documents/swift-src/llvm/lib/BinaryFormat/Dwarf.cpp:14:
In file included from /Users/suyashsrijan/Documents/swift-src/llvm/include/llvm/BinaryFormat/Dwarf.h:23:
In file included from /Users/suyashsrijan/Documents/swift-src/llvm/include/llvm/ADT/Optional.h:20:
/Users/suyashsrijan/Documents/swift-src/llvm/include/llvm/Support/AlignOf.h:37:3: error: unknown type name 'alignas'
alignas(Alignment) char buffer[Size];
^
/Users/suyashsrijan/Documents/swift-src/llvm/include/llvm/Support/AlignOf.h:37:11: error: declaration of 'Alignment' shadows template parameter
alignas(Alignment) char buffer[Size];
^
/Users/suyashsrijan/Documents/swift-src/llvm/include/llvm/Support/AlignOf.h:35:22: note: template parameter is declared here
template<std::size_t Alignment, std::size_t Size>
^
/Users/suyashsrijan/Documents/swift-src/llvm/include/llvm/Support/AlignOf.h:37:21: error: expected ';' at end of declaration list
alignas(Alignment) char buffer[Size];
^
;
/Users/suyashsrijan/Documents/swift-src/llvm/include/llvm/Support/AlignOf.h:140:59: error: expected
'(' for function-style cast or type construction
T6, T7, T8, T9, T10>),
~~~~~~~~~~~~~~~~~~~~^
/Users/suyashsrijan/Documents/swift-src/llvm/include/llvm/Support/AlignOf.h:142:61: error: expected class name
T6, T7, T8, T9, T10>)> {
^
Building with: build-script -x -r --clean --reconfigure --skip-build-benchmarks