groovy

Convariant returns causes compiler to fail when generating property getters

Details

  • Type: Bug Bug
  • Status: Closed Closed
  • Priority: Major Major
  • Resolution: Fixed
  • Affects Version/s: 1.7.6, 1.8-beta-3
  • Fix Version/s: 1.8.5, 2.0-beta-2, 1.7.11
  • Component/s: Compiler
  • Labels:
    None
  • Number of attachments :
    0

Description

When attempting to compile the following groovy code I get the compiler error under groovy 1.7.6 and 1.8.3-beta-3. This has to do with defining an interface (or class) with getters and then defining properties (or final members variables) on a subclass using covariant returns. I can work around this issue by explicitly defining the required getter in the subclass which is rather annoying b/c I like groovy getter generation and in our codebase we are running into this a lot. This is also a problem when using "def" types. I would be glad to assist in any way if I can. Thanks.

For example:

interface CovariantReturns {
  Foo getGood()
  Object getBad()
}

class Foo {}

class CovariantReturnsImpl implements CovariantReturns {
  //getter is generated by groovy as required by the interface
  final Foo good

  //this variable is defined as the subtype of Object
  final Foo bad

  /*
   I would expect that the following method would be generated by groovy
   which is using Java's covariant returns feature.  Including the method below
   will allow the groovy compiler to succeed but is annoying that it has to be explicitly
   defined in code.

   public Foo getBad() { return bad }
   */
}

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
CovariantReturns.groovy: 8: Can't have an abstract method in a non-abstract class. The class 'CovariantReturns
Impl' must be declared abstract or the method 'java.lang.Object getBad()' must be implemented.
 @ line 8, column 1.
   class CovariantReturnsImpl implements CovariantReturns {
   ^

1 error

Issue Links

relates to

Bug - A problem which impairs or prevents the functions of the product. GROOVY-4415 Error implementing a Java or Groovy generic interface

  • Major - Major loss of function.
  • Closed - The issue is considered finished, the resolution is correct. Issues which are not closed can be reopened.

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add code tags

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Field Original Value New Value
Description When attempting to compile the following groovy code I get the compiler error under groovy 1.7.6 and 1.8.3-beta-3. This has to do with defining an interface (or class) with getters and then defining properties (or final members variables) on a subclass using covariant returns. I can work around this issue by explicitly defining the required getter in the subclass which is rather annoying b/c I like groovy getter generation and in our codebase we are running into this a lot. This is also a problem when using "def" types. I would be glad to assist in any way if I can. Thanks.


For example:

interface CovariantReturns {
  Foo getGood()
  Object getBad()
}

class Foo {}

class CovariantReturnsImpl implements CovariantReturns {
  //getter is generated by groovy as required by the interface
  final Foo good

  //this variable is defined as the subtype of Object
  final Foo bad

  /*
   I would expect that the following method would be generated by groovy
   which is using Java's covariant returns feature. Including the method below
   will allow the groovy compiler to succeed but is annoying that it has to be explicitly
   defined in code.

   public Foo getBad() { return bad }
   */

}

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
CovariantReturns.groovy: 8: Can't have an abstract method in a non-abstract class. The class 'CovariantReturns
Impl' must be declared abstract or the method 'java.lang.Object getBad()' must be implemented.
 @ line 8, column 1.
   class CovariantReturnsImpl implements CovariantReturns {
   ^

1 error 		When attempting to compile the following groovy code I get the compiler error under groovy 1.7.6 and 1.8.3-beta-3. This has to do with defining an interface (or class) with getters and then defining properties (or final members variables) on a subclass using covariant returns. I can work around this issue by explicitly defining the required getter in the subclass which is rather annoying b/c I like groovy getter generation and in our codebase we are running into this a lot. This is also a problem when using "def" types. I would be glad to assist in any way if I can. Thanks.


For example:
{code}
interface CovariantReturns {
  Foo getGood()
  Object getBad()
}

class Foo {}

class CovariantReturnsImpl implements CovariantReturns {
  //getter is generated by groovy as required by the interface
  final Foo good

  //this variable is defined as the subtype of Object
  final Foo bad

  /*
   I would expect that the following method would be generated by groovy
   which is using Java's covariant returns feature. Including the method below
   will allow the groovy compiler to succeed but is annoying that it has to be explicitly
   defined in code.

   public Foo getBad() { return bad }
   */
}
{code}

{noformat}
org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
CovariantReturns.groovy: 8: Can't have an abstract method in a non-abstract class. The class 'CovariantReturns
Impl' must be declared abstract or the method 'java.lang.Object getBad()' must be implemented.
 @ line 8, column 1.
   class CovariantReturnsImpl implements CovariantReturns {
   ^

1 error
{noformat}
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Paul King added a comment -

Possibly overlaps with GROOVY-4415?

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Paul King added a comment - Possibly overlaps with GROOVY-4415 ?
Cedric Champeau made changes -
Link This issue relates to GROOVY-4415 [ GROOVY-4415 ]
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Cedric Champeau added a comment -

Same issue, two different ways of demonstrating.

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Cedric Champeau added a comment - Same issue, two different ways of demonstrating.
Cedric Champeau made changes -
Status Open [ 1 ] Resolved [ 5 ]
Assignee Cedric Champeau [ melix ]
Fix Version/s 2.0-beta-2 [ 18072 ]
Fix Version/s 1.7.11 [ 17244 ]
Fix Version/s 1.8.5 [ 18071 ]
Resolution Fixed [ 1 ]
Paul King made changes -
Status Resolved [ 5 ] Closed [ 6 ]

People

  • Assignee:
    Cedric Champeau
    Reporter:
    Travis
Vote (4)
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Dates

  • Created:
    Updated:
    Resolved: