// Parse the member reference of a struct (or union, soon)
// and return an AST tree for it. If withpointer is true,
// the access is through a pointer to the member.
static struct ASTnode *member_access(int withpointer) {
  struct ASTnode *left, *right;
  struct symtable *compvar;
  struct symtable *typeptr;
  struct symtable *m;

  // Check that the identifer has been declared as a struct (or a union, later),
  // or a struct/union pointer
  if ((compvar = findsymbol(Text)) == NULL)
    fatals("Undeclared variable", Text);
  if (withpointer && compvar->type != pointer_to(P_STRUCT))
    fatals("Undeclared variable", Text);
  if (!withpointer && compvar->type != P_STRUCT)
    fatals("Undeclared variable", Text);