heap-use-after-free at src/ast/ast.h:507:36

[merlinsun]

Hi,
For this instance, z3 fba5de3

$ cat small.smt2 
(declare-fun b (Int) Bool)
(assert (exists ((r String)) (distinct (- 1) (str.to_int (str.substr r 1 1)))))
(assert (forall ((v Int)) (exists ((a Int)) (not (b (+ 1 v))))))
(check-sat)
$ z3asan small.smt2 
=================================================================
==27873==ERROR: AddressSanitizer: heap-use-after-free on address 0x60700004f16c at pc 0x0000005e3867 bp 0x7ffd9c40eaf0 sp 0x7ffd9c40eae8
READ of size 4 at 0x60700004f16c thread T0
    #0 0x5e3866 in ast::hash() const /root/z3/build/../src/ast/ast.h:507:36
    #1 0x6eabdf in obj_map<expr, expr*>::key_data::hash() const /root/z3/build/../src/util/obj_hashtable.h:76:47
    #2 0x6eaae4 in obj_map<expr, expr*>::obj_map_entry::get_hash() const /root/z3/build/../src/util/obj_hashtable.h:84:51
......

SUMMARY: AddressSanitizer: heap-use-after-free /root/z3/build/../src/ast/ast.h:507:36 in ast::hash() const
......