running it in -v mode only yields an error: fatalError.
$ /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/bin/swiftc -v -output-file-map src/swift/CMakeFiles/swiftDispatch.dir/Release/output-file-map.json -incremental -j 12 -emit-library -o libswiftDispatch.so -module-name Dispatch -module-link-name swiftDispatch -emit-module -emit-module-path src/swift/swift/Dispatch.swiftmodule -emit-dependencies -DswiftDispatch_EXPORTS -module-cache-path "/swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/module-cache" -O -Xcc -fblocks -Xcc -fmodule-map-file=/swift/swift-project/swift-corelibs-libdispatch/dispatch/module.modulemap -Xcc -I/swift/swift-project/swift-corelibs-libdispatch -Xcc -I/swift/swift-project/swift-corelibs-libdispatch/src/swift/shims -vfsoverlay /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/dispatch-vfs-overlay.yaml -I /swift/swift-project/swift-corelibs-libdispatch/src/BlocksRuntime -I /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64 -I /swift/swift-project/swift-corelibs-libdispatch -I /swift/swift-project/swift-corelibs-libdispatch/src -I /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/src /swift/swift-project/swift-corelibs-libdispatch/src/swift/Block.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Data.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Dispatch.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/IO.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Private.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Queue.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Source.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Time.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Wrapper.swift -no-toolchain-stdlib-rpath -Xlinker -soname -Xlinker libswiftDispatch.so -L /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/src/swift -L /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64 -L /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64 -L /usr/lib/gcc/x86_64-amazon-linux/11 -Xlinker -rpath -Xlinker /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64: src/swift/libDispatchStubs.a libdispatch.so libBlocksRuntime.so -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc
Swift version 5.11-dev (LLVM 2a31eae409ff4ff, Swift f68e0c90f9784ab)
Target: x86_64-unknown-linux-gnu
/swift/swift-project/build/buildbot_linux/swift-linux-x86_64/bin/swift-frontend -frontend -c -primary-file /swift/swift-project/swift-corelibs-libdispatch/src/swift/Block.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Data.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Dispatch.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/IO.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Private.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Queue.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Source.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Time.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Wrapper.swift -emit-module-path src/swift/CMakeFiles/swiftDispatch.dir/Block.swift.swiftmodule -emit-module-doc-path src/swift/CMakeFiles/swiftDispatch.dir/Block.swift.swiftdoc -emit-module-source-info-path src/swift/CMakeFiles/swiftDispatch.dir/Block.swift.swiftsourceinfo -emit-dependencies-path src/swift/CMakeFiles/swiftDispatch.dir/Block.swift.o.d -emit-reference-dependencies-path src/swift/CMakeFiles/swiftDispatch.dir/Block.swift.o.swiftdeps -target x86_64-unknown-linux-gnu -disable-objc-interop -I /swift/swift-project/swift-corelibs-libdispatch/src/BlocksRuntime -I /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64 -I /swift/swift-project/swift-corelibs-libdispatch -I /swift/swift-project/swift-corelibs-libdispatch/src -I /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/src -vfsoverlay /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/dispatch-vfs-overlay.yaml -color-diagnostics -module-cache-path /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/module-cache -module-link-name swiftDispatch -O -D swiftDispatch_EXPORTS -new-driver-path /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/bin/swift-driver -empty-abi-descriptor -resource-dir /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/lib/swift -Xcc -fblocks -Xcc -fmodule-map-file=/swift/swift-project/swift-corelibs-libdispatch/dispatch/module.modulemap -Xcc -I/swift/swift-project/swift-corelibs-libdispatch -Xcc -I/swift/swift-project/swift-corelibs-libdispatch/src/swift/shims -module-name Dispatch -plugin-path /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/lib/swift/host/plugins -plugin-path /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/local/lib/swift/host/plugins -enable-default-cmo -parse-as-library -o src/swift/CMakeFiles/swiftDispatch.dir/Block.swift.o
/swift/swift-project/build/buildbot_linux/swift-linux-x86_64/bin/swift-frontend -frontend -c /swift/swift-project/swift-corelibs-libdispatch/src/swift/Block.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Data.swift -primary-file /swift/swift-project/swift-corelibs-libdispatch/src/swift/Dispatch.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/IO.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Private.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Queue.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Source.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Time.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Wrapper.swift -emit-module-path src/swift/CMakeFiles/swiftDispatch.dir/Dispatch.swift.swiftmodule -emit-module-doc-path src/swift/CMakeFiles/swiftDispatch.dir/Dispatch.swift.swiftdoc -emit-module-source-info-path src/swift/CMakeFiles/swiftDispatch.dir/Dispatch.swift.swiftsourceinfo -emit-dependencies-path src/swift/CMakeFiles/swiftDispatch.dir/Dispatch.swift.o.d -emit-reference-dependencies-path src/swift/CMakeFiles/swiftDispatch.dir/Dispatch.swift.o.swiftdeps -target x86_64-unknown-linux-gnu -disable-objc-interop -I /swift/swift-project/swift-corelibs-libdispatch/src/BlocksRuntime -I /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64 -I /swift/swift-project/swift-corelibs-libdispatch -I /swift/swift-project/swift-corelibs-libdispatch/src -I /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/src -vfsoverlay /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/dispatch-vfs-overlay.yaml -color-diagnostics -module-cache-path /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/module-cache -module-link-name swiftDispatch -O -D swiftDispatch_EXPORTS -new-driver-path /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/bin/swift-driver -empty-abi-descriptor -resource-dir /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/lib/swift -Xcc -fblocks -Xcc -fmodule-map-file=/swift/swift-project/swift-corelibs-libdispatch/dispatch/module.modulemap -Xcc -I/swift/swift-project/swift-corelibs-libdispatch -Xcc -I/swift/swift-project/swift-corelibs-libdispatch/src/swift/shims -module-name Dispatch -plugin-path /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/lib/swift/host/plugins -plugin-path /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/local/lib/swift/host/plugins -enable-default-cmo -parse-as-library -o src/swift/CMakeFiles/swiftDispatch.dir/Dispatch.swift.o
/swift/swift-project/build/buildbot_linux/swift-linux-x86_64/bin/swift-frontend -frontend -c /swift/swift-project/swift-corelibs-libdispatch/src/swift/Block.swift -primary-file /swift/swift-project/swift-corelibs-libdispatch/src/swift/Data.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Dispatch.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/IO.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Private.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Queue.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Source.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Time.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Wrapper.swift -emit-module-path src/swift/CMakeFiles/swiftDispatch.dir/Data.swift.swiftmodule -emit-module-doc-path src/swift/CMakeFiles/swiftDispatch.dir/Data.swift.swiftdoc -emit-module-source-info-path src/swift/CMakeFiles/swiftDispatch.dir/Data.swift.swiftsourceinfo -emit-dependencies-path src/swift/CMakeFiles/swiftDispatch.dir/Data.swift.o.d -emit-reference-dependencies-path src/swift/CMakeFiles/swiftDispatch.dir/Data.swift.o.swiftdeps -target x86_64-unknown-linux-gnu -disable-objc-interop -I /swift/swift-project/swift-corelibs-libdispatch/src/BlocksRuntime -I /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64 -I /swift/swift-project/swift-corelibs-libdispatch -I /swift/swift-project/swift-corelibs-libdispatch/src -I /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/src -vfsoverlay /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/dispatch-vfs-overlay.yaml -color-diagnostics -module-cache-path /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/module-cache -module-link-name swiftDispatch -O -D swiftDispatch_EXPORTS -new-driver-path /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/bin/swift-driver -empty-abi-descriptor -resource-dir /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/lib/swift -Xcc -fblocks -Xcc -fmodule-map-file=/swift/swift-project/swift-corelibs-libdispatch/dispatch/module.modulemap -Xcc -I/swift/swift-project/swift-corelibs-libdispatch -Xcc -I/swift/swift-project/swift-corelibs-libdispatch/src/swift/shims -module-name Dispatch -plugin-path /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/lib/swift/host/plugins -plugin-path /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/local/lib/swift/host/plugins -enable-default-cmo -parse-as-library -o src/swift/CMakeFiles/swiftDispatch.dir/Data.swift.o
/swift/swift-project/build/buildbot_linux/swift-linux-x86_64/bin/swift-frontend -frontend -c /swift/swift-project/swift-corelibs-libdispatch/src/swift/Block.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Data.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Dispatch.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/IO.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Private.swift -primary-file /swift/swift-project/swift-corelibs-libdispatch/src/swift/Queue.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Source.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Time.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Wrapper.swift -emit-module-path src/swift/CMakeFiles/swiftDispatch.dir/Queue.swift.swiftmodule -emit-module-doc-path src/swift/CMakeFiles/swiftDispatch.dir/Queue.swift.swiftdoc -emit-module-source-info-path src/swift/CMakeFiles/swiftDispatch.dir/Queue.swift.swiftsourceinfo -emit-dependencies-path src/swift/CMakeFiles/swiftDispatch.dir/Queue.swift.o.d -emit-reference-dependencies-path src/swift/CMakeFiles/swiftDispatch.dir/Queue.swift.o.swiftdeps -target x86_64-unknown-linux-gnu -disable-objc-interop -I /swift/swift-project/swift-corelibs-libdispatch/src/BlocksRuntime -I /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64 -I /swift/swift-project/swift-corelibs-libdispatch -I /swift/swift-project/swift-corelibs-libdispatch/src -I /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/src -vfsoverlay /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/dispatch-vfs-overlay.yaml -color-diagnostics -module-cache-path /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/module-cache -module-link-name swiftDispatch -O -D swiftDispatch_EXPORTS -new-driver-path /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/bin/swift-driver -empty-abi-descriptor -resource-dir /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/lib/swift -Xcc -fblocks -Xcc -fmodule-map-file=/swift/swift-project/swift-corelibs-libdispatch/dispatch/module.modulemap -Xcc -I/swift/swift-project/swift-corelibs-libdispatch -Xcc -I/swift/swift-project/swift-corelibs-libdispatch/src/swift/shims -module-name Dispatch -plugin-path /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/lib/swift/host/plugins -plugin-path /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/local/lib/swift/host/plugins -enable-default-cmo -parse-as-library -o src/swift/CMakeFiles/swiftDispatch.dir/Queue.swift.o
/swift/swift-project/build/buildbot_linux/swift-linux-x86_64/bin/swift-frontend -frontend -c /swift/swift-project/swift-corelibs-libdispatch/src/swift/Block.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Data.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Dispatch.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/IO.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Private.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Queue.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Source.swift /swift/swift-project/swift-corelibs-libdispatch/src/swift/Time.swift -primary-file /swift/swift-project/swift-corelibs-libdispatch/src/swift/Wrapper.swift -emit-module-path src/swift/CMakeFiles/swiftDispatch.dir/Wrapper.swift.swiftmodule -emit-module-doc-path src/swift/CMakeFiles/swiftDispatch.dir/Wrapper.swift.swiftdoc -emit-module-source-info-path src/swift/CMakeFiles/swiftDispatch.dir/Wrapper.swift.swiftsourceinfo -emit-dependencies-path src/swift/CMakeFiles/swiftDispatch.dir/Wrapper.swift.o.d -emit-reference-dependencies-path src/swift/CMakeFiles/swiftDispatch.dir/Wrapper.swift.o.swiftdeps -target x86_64-unknown-linux-gnu -disable-objc-interop -I /swift/swift-project/swift-corelibs-libdispatch/src/BlocksRuntime -I /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64 -I /swift/swift-project/swift-corelibs-libdispatch -I /swift/swift-project/swift-corelibs-libdispatch/src -I /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/src -vfsoverlay /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/dispatch-vfs-overlay.yaml -color-diagnostics -module-cache-path /swift/swift-project/build/buildbot_linux/libdispatch-linux-x86_64/module-cache -module-link-name swiftDispatch -O -D swiftDispatch_EXPORTS -new-driver-path /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/bin/swift-driver -empty-abi-descriptor -resource-dir /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/lib/swift -Xcc -fblocks -Xcc -fmodule-map-file=/swift/swift-project/swift-corelibs-libdispatch/dispatch/module.modulemap -Xcc -I/swift/swift-project/swift-corelibs-libdispatch -Xcc -I/swift/swift-project/swift-corelibs-libdispatch/src/swift/shims -module-name Dispatch -plugin-path /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/lib/swift/host/plugins -plugin-path /swift/swift-project/build/buildbot_linux/swift-linux-x86_64/local/lib/swift/host/plugins -enable-default-cmo -parse-as-library -o src/swift/CMakeFiles/swiftDispatch.dir/Wrapper.swift.o
/swift/swift-project/swift-corelibs-libdispatch/src/swift/Dispatch.swift:99:4: warning: default will never be executed
default: return nil
^
error: fatalError