What does %prec '.' mean here in yacc?

notype_declarator:
      notype_declarator '(' parmlist_or_identifiers  %prec '.'
        { $$ = build_nt (CALL_EXPR开发者_Python百科, $1, $3, NULL_TREE); }

Anyone familiar with yacc rules?

It declares that the construct has the same precedence as the '.' operator, which have been specified earlier.

yacc program for showing error for 1) redeclaration of variable 2) Assignment expression error 3) operator missing