Segfault via API when variable has empty name

[mikand]

The code below, causes a segfault in Z3 because of the variable b that has an empty name (if b is set to something, the code works perfectly).

from z3 import *

a = Bool('a')
b = Bool('') # b = Bool('b')
expr = And(a, b)

Z3_set_ast_print_mode(expr.ctx.ref(), Z3_PRINT_SMTLIB2_COMPLIANT)
s = Z3_benchmark_to_smtlib_string(expr.ctx.ref(),
                                  None, None,
                                  None, None,
                                  0, None,
                                  expr.ast)
print(s)

The issue arose in dealing with pysmt/pysmt#587, strangely enough Z3 is able to parse and solve https://clc-gitlab.cs.uiowa.edu:2443/SMT-LIB-benchmarks/QF_BV/blob/master/check2/symbols.smt2 but if the same formula is created via API it is unable to print it in SMT2 format.