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https://issues.apache.org/jira/browse/GROOVY-7597?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14947412#comment-14947412
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ASF GitHub Bot commented on GROOVY-7597:
----------------------------------------
Github user asfgit closed the pull request at:
https://github.com/apache/incubator-groovy/pull/126
> Static Compiler tries to cast delegate to target type of property accessor
> --------------------------------------------------------------------------
>
> Key: GROOVY-7597
> URL: https://issues.apache.org/jira/browse/GROOVY-7597
> Project: Groovy
> Issue Type: Bug
> Components: Static compilation, Static Type Checker
> Affects Versions: 2.4.3, 2.4.4
> Reporter: Jason Winnebeck
> Assignee: Cédric Champeau
>
> I've been able to finally isolate a static compiler issue with accessing
> properties on delegates that occur within our projects:
> {code}
> class Calculation {
> boolean isValid() { true }
> }
> class Entity {
> Calculation getCalculation(String name) { new Calculation() }
> }
> class Feature extends Entity {
> }
> void DoWithFeature(@DelegatesTo(Feature) Closure c) {
> new Feature().with(c)
> }
> @groovy.transform.CompileStatic
> void doIt() {
> DoWithFeature() {
> println getCalculation("whatever").valid
> }
> }
> doIt()
> {code}
> The result is {{java.lang.ClassCastException: Feature cannot be cast to
> Calculation}}
> Workarounds:
> * change the property access into a method access "valid" -> "isValid()"
> * Remove CompileStatic annotation
> As seen in the following bytecode, the static compiler tries to cast the
> delegate to Calculation (which always fails), then tries to call
> ScriptBytecodeAdapter.castToType to try to cast the "Calculation" back to an
> Entity to properly call getCalculation("").isValid() on it.
> {code}
> // access flags 0x1
> public doCall(Ljava/lang/Object;)Ljava/lang/Object;
> L0
> LINENUMBER 19 L0
> ALOAD 0
> CHECKCAST script1442861431462$_doIt_closure1
> INVOKEVIRTUAL script1442861431462$_doIt_closure1.getThisObject
> ()Ljava/lang/Object;
> LDC Lgroovy/lang/Script;.class
> INVOKESTATIC org/codehaus/groovy/runtime/ScriptBytecodeAdapter.castToType
> (Ljava/lang/Object;Ljava/lang/Class;)Ljava/lang/Object;
> CHECKCAST groovy/lang/Script
> ALOAD 0
> CHECKCAST script1442861431462$_doIt_closure1
> INVOKEVIRTUAL script1442861431462$_doIt_closure1.getDelegate
> ()Ljava/lang/Object;
> CHECKCAST Calculation
> LDC LEntity;.class
> INVOKESTATIC org/codehaus/groovy/runtime/ScriptBytecodeAdapter.castToType
> (Ljava/lang/Object;Ljava/lang/Class;)Ljava/lang/Object;
> CHECKCAST Entity
> LDC "whatever"
> INVOKEVIRTUAL Entity.getCalculation (Ljava/lang/String;)LCalculation;
> INVOKEVIRTUAL Calculation.isValid ()Z
> INVOKESTATIC java/lang/Boolean.valueOf (Z)Ljava/lang/Boolean;
> INVOKEVIRTUAL groovy/lang/Script.println (Ljava/lang/Object;)V
> ACONST_NULL
> ARETURN
> L1
> ACONST_NULL
> ARETURN
> LOCALVARIABLE this Lscript1442861431462$_doIt_closure1; L0 L1 0
> LOCALVARIABLE it Ljava/lang/Object; L0 L1 1
> MAXSTACK = 3
> MAXLOCALS = 2
> {code}
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