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https://issues.apache.org/jira/browse/GROOVY-11967?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18076320#comment-18076320
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ASF GitHub Bot commented on GROOVY-11967:
-----------------------------------------
paulk-asert opened a new pull request, #2493:
URL: https://github.com/apache/groovy/pull/2493
…valued list parameter
> 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
> Priority: Major
>
> 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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