Partial copy of my reply from StackOverflow:

Unfortunately this is currently not possible without hacking the core. The problem is that Form contains a references to FormError objects, which do not keep references to the original ConstraintViolation objects, which also do not keep references of the group under which the violation occurred.

Even if we added this feature, the problem would remain that a constraint is only evaluated once if it belongs to multiple groups that are validated at once. The violation would then only store the first group, even though it would have failed in the other groups too.

If the binding process loops on every constraints of each validation-group (but validate them only if not done yet), it must be possible to keep tracks on every failled constraint in each group ?

Can we state that, if a validation constraint fails in a validation group, it will fail for other group it's in ?

If the binding process loops on every constraints of each validation-group (but validate them only if not done yet), it must be possible to keep tracks on every failled constraint in each group ?

Not really, because the validation process does not control and modify the violations added by each validator. What you ask for is to change the violation afterwards to also include the groups that it would have occurred in. I don't like that smell...

Can we state that, if a validation constraint fails in a validation group, it will fail for other group it's in ?

Correct :) (unless you have a custom constraint that does funky stuff based on the current group, which I absolutely discourage)

The FormError now has a reference to the ConstraintViolation causing it (through getCause() since 2.5. Once #11657 will be merged in 2.6, the violation will give you access to the Constraint itself. So doing such grouping of errors will become possible in 2.6 (by getting all form errors, which is already possible in 2.5, and grouping them in userland)

@stof Correct.