QF_SLIA solution soundness bug with str.substr

[Chengyu Zhang]

[557] % z3release small.smt2
unsat
[558] % cvc4 -q --strings-exp small.smt2
unsat
[559] % ostrich +quiet small.smt2
sat
[560] % 
[560] % cat small.smt2
(declare-fun a () Int)
(assert (distinct (str.substr "A" 0 (+ a a)) (str.substr "A" 0 a)))
(check-sat)
[561] % 

Commit: 2f3ea5c

[Philipp Ruemmer]

Thanks; those are again inputs outside of the handled fragment, but now (in the latest master) a proper error message should be produced.

[Chengyu Zhang]

Double verified ostrich produces the expected error message now.