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From "Robert Stagner (JIRA)" <j...@apache.org>
Subject [jira] [Created] (GROOVY-9074) CompileStatic
Date Wed, 10 Apr 2019 17:30:00 GMT
Robert Stagner created GROOVY-9074:
--------------------------------------

             Summary: CompileStatic 
                 Key: GROOVY-9074
                 URL: https://issues.apache.org/jira/browse/GROOVY-9074
             Project: Groovy
          Issue Type: Bug
          Components: Compiler
    Affects Versions: 2.5.5
            Reporter: Robert Stagner


While reading about Java Generics and wildcards (see [https://docs.oracle.com/javase/tutorial/extra/generics/wildcards.html]),
I came across the following code in the referenced oracle document
{code:java}
Collection<?> c = new ArrayList<String>();
 c.add(new Object()); // Compile time error{code}
Now, I decided to wrap this in a class and try it out in Java and then in Groovy.

Here is the Java code

 
{code:java}
import java.util.*;
public class TestCollection {
 static Collection<?> c = new ArrayList<String>();
 public static void main(String[] args) {
   c.add(new Object()); // Compile time error
 }
}
{code}
 

  

and here is the groovy code

 
{code:java}
import java.util.*;
import groovy.transform.CompileStatic;

@CompileStatic
public class TestCollection {
 static Collection<?> c = new ArrayList<String>();
 public static void main(String[] args) {
   c.add(new Object()); // Compile time error
   println c.first();
 }
}
{code}
 

When I attempt to compile the Java code I get the following expected error
{code:java}
$ javac TestCollection.java
 TestCollection.java:7: error: incompatible types: Object cannot be converted to CAP#1
 c.add(new Object()); // Compile time error
 ^
 where CAP#1 is a fresh type-variable:
 CAP#1 extends Object from capture of ?{code}
But, when I run the code through Groovy, I do not get a compile-time error.  Instead, I get
the following output


{code:java}
java.lang.Object@41a0aa7d{code}



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