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https://issues.apache.org/jira/browse/GROOVY-11967?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Paul King resolved GROOVY-11967.
--------------------------------
    Fix Version/s: 6.0.0-alpha-1
       Resolution: Fixed

> VerifyError in @CompileStatic constructor with default-valued list parameter
> ----------------------------------------------------------------------------
>
>                 Key: GROOVY-11967
>                 URL: https://issues.apache.org/jira/browse/GROOVY-11967
>             Project: Groovy
>          Issue Type: Bug
>            Reporter: Paul King
>            Assignee: Paul King
>            Priority: Major
>             Fix For: 6.0.0-alpha-1
>
>
> h3. Summary
> A {{@CompileStatic}} class with a constructor that has a default-valued 
> list-literal parameter triggers {{VerifyError}} when the synthesised 
> lower-arity bridge constructor is loaded.
> h3. Repro
> {code:java}
> @CompileStatic
> class Foo {
>     Foo(Class<?> a, MessageSource b, List<Class> targetTypes = [Object]) {
>     }
> }
> new Foo(String, ms) // boom
> {code}
> h3. Symptom
> {noformat}
> java.lang.VerifyError: Bad type on operand stack
>   Location: Foo.<init>(Ljava/lang/Class;LMessageSource;)V @20: invokevirtual
>   Reason:   Type 'java/lang/Object' (current frame, stack[4]) is not 
> assignable to 'java/util/ArrayList'
> {noformat}
> h3. Root cause
> Introduced by GROOVY-8699 (commit {{7b18440c4f}}, master only). That change 
> replaced the {{ScriptBytecodeAdapter.createList(Object[])}} call (returns 
> {{List}}) with direct {{new ArrayList\(n) + .add(...)}} bytecode, generated 
> by {{ListExpressionTransformer$NewListExpression.visit()}}.
> In indy mode the constructor call lowers to {{invokedynamic 
> init:(Class;I)Object}} -- the JVM stack value is typed as {{Object}}, so the 
> subsequent {{INVOKEVIRTUAL java/util/ArrayList.add(Object)Z}} fails 
> verification because its receiver is not an {{ArrayList}}. The {{CHECKCAST}} 
> to {{List}} added later by the transformer happens after the {{add}} call, 
> too late.
> h3. Scope
> Not specific to {{List<Class>}} -- any default {{[...]}} literal in a 
> {{@CompileStatic}} constructor is affected ({{List<String>}}, 
> {{List<Integer>}}, {{List<List<String>>}}, etc.). Map defaults go through a 
> different transformer and are not affected.
> h3. Fix
> Insert {{CHECKCAST java/util/ArrayList}} immediately after the constructor 
> call in {{ListExpressionTransformer$NewListExpression.visit()}}, before the 
> loop that emits the per-element {{DUP / add / pop}}.
> h3. Affects
> Master only. Groovy 5.0.x and earlier are fine (used the 
> {{createList(Object[])}} helper).



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