eclipse升级到4.2 kepler后，发现php项目的代码提示啥的都不灵了，F3或者ctrl+左键都没反应，查了半天，原来是4.2版本的代码索引格式不兼容老版本了，需要到eclipse工作空间下，找到并删除workspace/.metadata/.plugins/org.eclipse.dltk.core.index.sql.h2，重启即可。

方案来自stackoverflow:

I had the same problem when upgrading eclipse to Kepler. The following worked for me:
Remove files under workspace/.metadata/.plugins/org.eclipse.dltk.core.index.sql.h2
The reason was that the workspace old DLTK index is not compliant with the new version and needs to be rebuilt. Start eclipse and the DLTK index will be regenerated.
Code completion worked for me again after that.