Function filterAttempt

pkg/sql/sem/tree/overload.go:744–760

filterAttempt attempts to filter the overloads down to a single candidate. If it succeeds, it will return true, along with the overload (in a slice for convenience) and a possible error. If it fails, it will return false and undo any filtering performed during the attempt.

(
	ctx *SemaContext, s *typeCheckOverloadState, attempt func(),
)

// convenience) and a possible error. If it fails, it will return false and
// undo any filtering performed during the attempt.
func filterAttempt(
	ctx *SemaContext, s *typeCheckOverloadState, attempt func(),
) (ok bool, _ []TypedExpr, _ []overloadImpl, _ error) {
	before := s.overloadIdxs
	attempt()
	if len(s.overloadIdxs) == 1 {
		ok, typedExprs, fns, err := checkReturn(ctx, s)
		if err != nil {
			return false, nil, nil, err
		}
		if ok {
			return true, typedExprs, fns, err
		}
	}
	s.overloadIdxs = before
	return false, nil, nil, nil
}

// filterOverloads filters overloads which do not satisfy the predicate.
func filterOverloads(