Welcome to the Haiku shell.

~/webkit/Tools/Scripts> build-webkit --haiku
Use of uninitialized value $previousContents in chomp at /boot/home/webkit/Tools/Scripts/webkitdirs.pm line 1991.
Use of uninitialized value $previousContents in string ne at /boot/home/webkit/Tools/Scripts/webkitdirs.pm line 1994.
+  cmake --build /boot/home/webkit/WebKitBuild/Release --config Release -- -j4

[  1%] Built target JavaScriptCoreForwardingHeaders
[  3%] Built target stageSharedScripts
[ 19%] Built target WTFForwardingHeaders
[ 46%] Built target JavaScriptCorePrivateForwardingHeaders
[ 47%] Generate bindings (WebCoreBindings)
[ 47%] Built target PALForwardingHeaders
[ 47%] Generate bindings (DumpRenderTreeBindings)
[ 47%] Built target ImageDiff
[ 47%] Built target DumpRenderTreeBindings
[ 52%] Built target WTF
[ 52%] Built target WebCoreBindings
[ 53%] Built target LLIntOffsetsExtractor
[ 53%] Generating ../../DerivedSources/JavaScriptCore/LLIntAssembly.h
offlineasm: Nothing changed.
[ 53%] Generating ../../DerivedSources/JavaScriptCore/LLIntAssembly.h
offlineasm: Nothing changed.
[ 53%] Linking CXX shared library ../../lib/libJavaScriptCore.so
[ 64%] Built target JavaScriptCore
[ 64%] Built target PAL
[ 64%] Built target jsc
[ 64%] Building CXX object Source/WebCore/CMakeFiles/WebCore.dir/platform/haiku/MainThreadSharedTimerHaiku.cpp.o
[ 64%] Building CXX object Source/WebCore/CMakeFiles/WebCore.dir/platform/haiku/PlatformScreenHaiku.cpp.o
[ 64%] Building CXX object Source/WebCore/CMakeFiles/WebCore.dir/platform/haiku/PlatformWheelEventHaiku.cpp.o
[ 64%] Building CXX object Source/WebCore/CMakeFiles/WebCore.dir/platform/haiku/PopupMenuHaiku.cpp.o
/boot/home/webkit/Source/WebCore/platform/haiku/MainThreadSharedTimerHaiku.cpp:35:10: fatal error: wtf/CurrentTime.h: No such file or directory
 #include <wtf/CurrentTime.h>
          ^~~~~~~~~~~~~~~~~~~
compilation terminated.
Source/WebCore/CMakeFiles/WebCore.dir/build.make:2580: recipe for target 'Source/WebCore/CMakeFiles/WebCore.dir/platform/haiku/MainThreadSharedTimerHaiku.cpp.o' failed
make[2]: *** [Source/WebCore/CMakeFiles/WebCore.dir/platform/haiku/MainThreadSharedTimerHaiku.cpp.o] Error 1
make[2]: *** Waiting for unfinished jobs....
CMakeFiles/Makefile2:515: recipe for target 'Source/WebCore/CMakeFiles/WebCore.dir/all' failed
make[1]: *** [Source/WebCore/CMakeFiles/WebCore.dir/all] Error 2
Makefile:151: recipe for target 'all' failed
make: *** [all] Error 2
~/webkit/Tools/Scripts>