; EXPECT: unsat
; COMMAND-LINE: --cegqi-si=all --sygus-out=status
(set-logic ALL_SUPPORTED)

(declare-datatypes ((List 0)) (((cons (head Int) (tail List)) (nil))))

(synth-fun f ((x Int)) List)

(declare-var x Int)

(constraint (is-cons (f x)))
(constraint (= (head (f x)) (+ x 7)))
(check-synth)