When trying to compile newer webkitgtk versions with bison 2.4.x, it fails: /usr/bin/bison -d -p jscyy ./JavaScriptCore/parser/Grammar.y -o DerivedSources/Grammar.cpp > bison_out.txt 2>&1 make: *** [DerivedSources/Grammar.cpp] Error 141 Bison does not parse the file at all and silently skips it (manually parsing also fails, no output whatoever even with -v).
I have bison 2.4.1 and this does not appear to be an issue. Going to close this bug, but please re-open if you are still having issue.