[bv-dev] Distinguishing cross-parameter and generic constraints

Hi all, As per the latest spec draft, a constraint must be either a cross-parameter *or* a generic constraint, but not both at the same time, as otherwise it would be ambiguous whether a constraint on a method refers to the method parameters or return value. Most of the time this does not really pose a limitation, but some constraints actually might be both, cross-parameter *and* generic, depending on the specific context. Examples are @ScriptAssert in Hibernate Validator or generic constraints such as this: @EqualPasswords public void register(String userName, String password, String confirmedPassword) { } @EqualPasswords public class ResetPasswordRequest { String userName; String password; String confirmedPassword; } Based on a recent BVAL issue [1], I'm proposing to introduce a special constraint annotation attribute, "validationAppliesTo", allowing to specify the required behavior at the usage site: @EqualPasswords(validationAppliesTo=PARAMETERS) public void register(String username, String password, String confirmPassword) { } @EqualPasswords(validationAppliesTo=ANNOTATED_ELEMENT) public class ResetPasswordRequest { String password; String confirmedPassword; } The following rules would apply: * If a constraint is annotated with @Constraint and @CrossParameterConstraint, it must define a member "validationAppliesTo". The default value should be ANNOTATED_ELEMENT. * If a constraint is annotated with only one of @Constraint/@CrossParameterConstraint, defining a "validationAppliesTo" member doesn't have any special effect * Specifying validationAppliesTo=PARAMETERS anywhere except a method causes ConstraintDeclarationException Any thoughts? --Gunnar [1] https://hibernate.onjira.com/browse/BVAL-340