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  1. JDK
  2. JDK-4214318

explicit constructor invocation as a right-hand operand of assignment

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    • sparc
    • solaris_2.5.1

    Description



      Name: laC46010 Date: 02/23/99



      Constructor invocation can not be the right-hand operand of an assignment
      since it doesn't return anything :

      (field = field).this(); // legal
      field = field.this(); // illegal but javac allows it

      (See latest 'Clarifications and Amendments to the Inner Classes Specification' and
       JLS 19.8.5 :
      ExplicitConstructorInvocation: ...
      Primary . this ( ArgumentList opt ) ;
      Primary . super ( ArgumentList opt ) ;
      this ( ArgumentList opt ) ;
      super ( ArgumentList opt ) ;
      )

      Javac seems to treat unparenthesized assignment here as a Primary, what contradicts the
      grammar (JLS 19.12).

      Javac (1.2fcs, 1.2.2) compiles the following programs without reporting any errors,
      while earlier versions (1.1.x, 1.2beta1,2,3,4) give compilation errors :

      1)
      ------------- test.java -----------
      public class test {
      static test field = new test();
      int var = 0;

      class C extends test {
      C() {}
      C(int a) {
      field = field.this(); // compiler should emit an error here
      field.var = a;
      }
      }

      public static void main( String args[] ) {
      test v1 = new test();
      C v2 = v1.new C(10);
      System.out.println("v2.var = " + v2.var);
      }
      }
      --------- end of test.java --------

      This program outputs :
      -----------
      > java test
      v2.var = 0
      -----------

      2)
      ------------- test.java -----------
      public class test {
      static test field = new test();
      int var = 0;
      }

      class C extends test {
      C() {}
      C(int a) {
      field = field.this(); // compiler should emit an error here
      field.var = a;
      }
      }
      --------- end of test.java --------

      ======================================================================

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            wmaddoxsunw William Maddox (Inactive)
            leosunw Leo Leo (Inactive)
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