dev-java/swt-3.8.2-r1 fails on the prepare step applying swt-3.8.2-libwebkit-compat.patch. I was able to trace this to the fact that the patch has these lines: long /*int*/ session = WebKitGTK.webkit_get_default_session (); long /*int*/ originalAuth = WebKitGTK.soup_session_get_feature (session, WebKitGTK.webkit_soup_auth_dialog_get_type ()); ...whereas the file being patched (src/org/eclipse/swt/browser/WebKit.java) has: int /*long*/ session = WebKitGTK.webkit_get_default_session (); int /*long*/ originalAuth = WebKitGTK.soup_session_get_feature (session, WebKitGTK.webkit_soup_auth_dialog_get_type ()); ...at line 598. That is "long /*int*/" vs "int /*long*/".
I manually applied the change, and after that the emerge ran fine.
This appears to be fixed as of swt-3.7.2-r2.
We no longer enable webkit so this isn't an issue now.