Add regression tests for circular type definitions

Check that circular type definitions are detected and an error is
reported.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>

ivtest/ivltests/sv_typedef_circular1.v

@@ -0,0 +1,14 @@
+// Check that circular type definitions are detected and an error is reported.
+
+module test;
+  typedef T1;
+  typedef T1 T2;
+  typedef T2 T1;
+
+  T2 x;
+
+  initial begin
+    $display("FAILED");
+  end
+
+endmodule

ivtest/ivltests/sv_typedef_circular2.v

@@ -0,0 +1,18 @@
+// Check that longer chains of circular type definitions are detected as an
+// error.
+
+module test;
+
+  typedef T1;
+
+  typedef struct packed {
+    T1 x;
+  } T2;
+
+  typedef T2 [1:0] T3;
+
+  typedef T3 T1;
+
+  T1 x;
+
+endmodule

ivtest/regress-sv.list

@@ -716,6 +716,8 @@ sv_typedef_array_base2	normal,-g2009		ivltests
 sv_typedef_array_base3	normal,-g2009		ivltests
 sv_typedef_array_base4	normal,-g2009		ivltests
 sv_typedef_chained	normal,-g2009		ivltests
+sv_typedef_circular1	CE,-g2009		ivltests
+sv_typedef_circular2	CE,-g2009		ivltests
 sv_typedef_darray_base1	normal,-g2009		ivltests
 sv_typedef_darray_base2	normal,-g2009		ivltests
 sv_typedef_darray_base3	normal,-g2009		ivltests