Merge pull request #792 from diffblue/low1-fix

Verilog: zero_extend now considers genvar

Author: tautschnig

regression/verilog/system-functions/low1.desc

@@ -1,9 +1,8 @@
-KNOWNBUG
+CORE broken-smt-backend
 low1.sv
 --module main --bound 0
 ^EXIT=0$
 ^SIGNAL=0$
 --
 ^warning: ignoring
 --
-This yields an error in the typechecker.

src/verilog/verilog_typecheck_expr.cpp

@@ -2351,8 +2351,9 @@ Function: zero_extend
 
 static exprt zero_extend(const exprt &expr, const typet &type)
 {
-  auto old_width = expr.type().id() == ID_bool
-                     ? 1
+  auto old_width = expr.type().id() == ID_bool ? 1
+                   : expr.type().id() == ID_integer
+                     ? 32
                      : to_bitvector_type(expr.type()).get_width();
 
   // first make unsigned