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?

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

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