Scott Murphy Heiberg created GROOVY-12684:
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Summary: Attribute access on a closure reads and writes the
private implementation fields of Closure
Key: GROOVY-12684
URL: https://issues.apache.org/jira/browse/GROOVY-12684
Project: Groovy
Issue Type: Improvement
Affects Versions: 6.0.0
Reporter: Scott Murphy Heiberg
Attribute access ({{.@}}) on a closure reaches the private implementation
fields of {{groovy.lang.Closure}}, although the closure is an instance of a
generated subclass and attribute access does not reach a superclass's private
fields for any other class:
{code:groovy}
def c = { -> 1 }
c.@thisType = String // overwrites Closure's private field
assert c.@thisType == String
c.@bcw // reads Closure's private BooleanClosureWrapper cache
class A { private int x = 1 }
class B extends A {}
new B().@x // MissingFieldException
{code}
{{c.@delegate}}, {{c.@owner}}, {{c.@thisObject}}, {{c.@resolveStrategy}} and
{{c.@maximumNumberOfParameters}} reach private fields of {{Closure}} the same
way, and existing code relies on them (for example to read the owner without
going through {{getOwner()}}). So the choice is between leaving attribute
access as it is, and declining the fields that are implementation details
({{thisType}}, {{bcw}}, {{serialVersionUID}} and any later caches) while
keeping the ones code uses today.
GROOVY-12680 (apache/groovy#3201) stops {{ClosureMetaClass}} from exposing the
private fields of {{Closure}} as properties ({{c.thisType}}, {{c.bcw}}); it
leaves attribute access unchanged. Seen on 6.0.0 and master. In 4.0.33 the
{{thisType}} field does not exist.
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