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  1. Groovy
  2. GROOVY-10367

STC fails to infer the correct type for type variable in the presence of the diamond operator and bounded polymorphism

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    Description

      This issue may be related to GROOVY-10343.

      I have the following program

      class A<Z, P extends Z> {
        Z f;
        A(Z f) {}
      }
      
      class B<Z extends Number> {
        Z f;
      
        void test() {
          f = new A<>((Z) null).f;
        }
      }
      

      Actual behaviour

      org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
      test.groovy: 10: [Static type checking] - Cannot assign value of type java.lang.Object to variable of type Z
       @ line 10, column 9.
             f = new A<>((Z) null).f;
                 ^
      
      1 error
      

      Expected behaviour

      Compile successfully

      NOTE: Replacing `Z extends Number` with `Z` leads to a successful compilation.

      Tested against master (https://github.com/apache/groovy/commit/cf2f77fb033a10d36c4db3a7ff07a2b04631afcf)

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            emilles Eric Milles
            theosot Thodoris Sotiropoulos
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              Updated:
              Resolved:

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