Parser: performMethodsFullRecovery vs performStatementsRecovery

[mickaelistria]

Hi,
While looking at making some operation DOM-first, and basically replacing some direct usages of ECJ Parser with higher-level ASTParser, I'm facing some issue about performMethodsFullRecovery vs performStatementsRecovery. Some of the model tests for instance do work only if this couple is set to (true, false), while going with ASTParser, there is currently no way to uncouple those values, so it's either (true, true) or (false, false). Looking at the definition in code, both give same documentation. I tried to look at how parser does use one vs the other but didn't manage to understand the intended difference.
So can someone please clarify why there are 2 distinct fields here? And how is the combination (performMethodsFullRecovery=true, performStatementsRecovery=false) so critical that many tests start failing when we try to change it?
Thanks in advance.