Unexpected Side Effects When backtracking in a CstParser

[bd82]

Is the CST created for a backtracked rule ignored? or are there side effects from building the CST
and "rewinding" after back tracking?

[bd82]

It seems that it does because the cstPostNonTerminal method does not take it int account.

There are more things to consider here:

• Should backtracking disable CST building completely or just the side effects.
  • Without the partial CST results some grammars (that reflect on the CST and modify GATES) may break.
  • But in other cases the CST is completely redundant while backtracking so avoiding its creation would improve performance.

[bd82]

See the "fix" in prettier-java

• https://github.com/jhipster/prettier-java/blob/73a888d5e0df2bb206364088cc9c6740c197a573/packages/java-parser/src/parser.js#L148-L154

[bd82]

What are the performance implications for fixing this?