use ID_frontend_vector in the C front-end

The gcc vector type attribute that comes out of the C parser is not yet a
full vector_typet -- thus use ID_frontend_vector to avoid the ambiguity.

Author: kroening

src/ansi-c/ansi_c_convert_type.cpp

@@ -187,8 +187,11 @@ void ansi_c_convert_typet::read_rec(const typet &type)
   {
     c_qualifiers.is_transparent_union=true;
   }
-  else if(type.id()==ID_vector)
-    vector_size=to_vector_type(type).size();
+  else if(type.id() == ID_frontend_vector)
+  {
+    // note that this is not yet a vector_typet -- this is a size only
+    vector_size = static_cast<const constant_exprt &>(type.find(ID_size));
+  }
   else if(type.id()==ID_void)
   {
     // we store 'void' as 'empty'

src/ansi-c/parser.y

@@ -1607,7 +1607,7 @@ gcc_type_attribute:
         | TOK_GCC_ATTRIBUTE_TRANSPARENT_UNION
         { $$=$1; set($$, ID_transparent_union); }
         | TOK_GCC_ATTRIBUTE_VECTOR_SIZE '(' comma_expression ')'
-        { $$=$1; set($$, ID_vector); parser_stack($$).add(ID_size)=parser_stack($3); }
+        { $$=$1; set($$, ID_frontend_vector); parser_stack($$).add(ID_size)=parser_stack($3); }
         | TOK_GCC_ATTRIBUTE_ALIGNED
         { $$=$1; set($$, ID_aligned); }
         | TOK_GCC_ATTRIBUTE_ALIGNED '(' comma_expression ')'