Small fixes based on review

will be squashed.

Author: petr-bauch

regression/cbmc/incomplete-sizeof-enum/test.desc

@@ -0,0 +1,9 @@
+CORE
+array.c
+
+^EXIT=6$
+^SIGNAL=0$
+^file array.c line \d+ function main: invalid application of \'sizeof\' to an incomplete type$
+^CONVERSION ERROR$
+--
+^warning: ignoring

regression/cbmc/incomplete-sizeof-struct/test.desc

@@ -1,9 +1,9 @@
 CORE
-main.c
+enum.c
 
 ^EXIT=6$
 ^SIGNAL=0$
-^file main.c line \d+ function main: invalid application of \'sizeof\' to an incomplete type$
+^file enum.c line \d+ function main: invalid application of \'sizeof\' to an incomplete type$
 ^CONVERSION ERROR$
 --
 ^warning: ignoring

regression/cbmc/incomplete-sizeof-union/test.desc

@@ -0,0 +1,9 @@
+CORE
+struct.c
+
+^EXIT=6$
+^SIGNAL=0$
+^file struct.c line \d+ function main: invalid application of \'sizeof\' to an incomplete type$
+^CONVERSION ERROR$
+--
+^warning: ignoring

regression/cbmc/incomplete-sizeof-array/main.c renamed to regression/cbmc/incomplete-sizeof/array.c

@@ -0,0 +1,9 @@
+CORE
+union.c
+
+^EXIT=6$
+^SIGNAL=0$
+^file union.c line \d+ function main: invalid application of \'sizeof\' to an incomplete type$
+^CONVERSION ERROR$
+--
+^warning: ignoring

regression/cbmc/incomplete-sizeof/array.desc

@@ -953,11 +953,11 @@ void c_typecheck_baset::typecheck_expr_sizeof(exprt &expr)
   {
     if(
       (type.id() == ID_struct_tag &&
-       to_struct_type(follow_tag(to_struct_tag_type(type))).is_incomplete()) ||
+       follow_tag(to_struct_tag_type(type)).is_incomplete()) ||
       (type.id() == ID_union_tag &&
-       to_union_type(follow_tag(to_union_tag_type(type))).is_incomplete()) ||
+       follow_tag(to_union_tag_type(type)).is_incomplete()) ||
       (type.id() == ID_c_enum_tag &&
-       to_c_enum_type(follow_tag(to_c_enum_tag_type(type))).is_incomplete()) ||
+       follow_tag(to_c_enum_tag_type(type)).is_incomplete()) ||
       (type.id() == ID_array && to_array_type(type).is_incomplete()))
     {
       error().source_location = expr.source_location();