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https://issues.apache.org/jira/browse/GROOVY-12595?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18142711#comment-18142711
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ASF GitHub Bot commented on GROOVY-12595:
-----------------------------------------
paulk-asert opened a new pull request, #3291:
URL: https://github.com/apache/groovy/pull/3291
…ted calls on flow-typed variables
A call on a variable whose stored type is wider than its inferred type is
bound to the stored type without a cast (GROOVY-12469). That is wrong for an
array clone(), e.g. { it.clone() } over a float[][], and for protected methods
called from another package: the verifier requires those receivers to have the
array type, or the calling class, and fails with "Bad access to protected data".
> @CompileStatic: calling clone() on an element of a multi-dimensional array
> fails bytecode verification
> ------------------------------------------------------------------------------------------------------
>
> Key: GROOVY-12595
> URL: https://issues.apache.org/jira/browse/GROOVY-12595
> Project: Groovy
> Issue Type: Bug
> Reporter: Paul King
> Assignee: Paul King
> Priority: Major
> Fix For: 7.0.0-alpha-1, 6.0.1
>
>
> Under {{@CompileStatic}}, calling {{clone()}} directly on an element read
> from an array of arrays generates bytecode that the JVM verifier rejects.
> This happens for both primitive and reference element types.
> {code:groovy}
> import groovy.transform.CompileStatic
> @CompileStatic
> class C {
> static float[] one(float[][] a) { a[0].clone() }
> static String[] two(String[][] a) { a[0].clone() }
> }
> float[][] f = [[1f, 2f] as float[]]
> assert C.one(f) == [1f, 2f] as float[]
> {code}
> Loading {{C}} fails:
> {noformat}
> java.lang.VerifyError: Bad access to protected data in invokevirtual
> Exception Details:
> Location:
> C.one([[F)[F @5: invokevirtual
> Reason:
> Type 'java/lang/Object' (current frame, stack[0]) is not assignable to 'C'
> {noformat}
> h3. Generated bytecode
> {noformat}
> 0: aload_0
> 1: iconst_0
> 2: invokestatic
> org/codehaus/groovy/runtime/BytecodeInterface8.objectArrayGet:([Ljava/lang/Object;I)Ljava/lang/Object;
> 5: invokevirtual java/lang/Object.clone:()Ljava/lang/Object; <-- receiver
> is still typed Object; no checkcast [F
> 8: invokedynamic cast:(Ljava/lang/Object;)[F
> {noformat}
> h3. Cause
> The type checker models array {{clone()}} as {{Object#clone()}} (see
> GROOVY-10319). When it computes the receiver cast,
> {{StaticInvocationWriter.CheckcastReceiverExpression#getType()}} skips the
> {{checkcast}} whenever the target is declared on {{Object}}. But
> {{Object#clone()}} is protected, so the verifier only accepts the
> {{invokevirtual}} if the receiver is the calling class or an array type. An
> element read with {{objectArrayGet}} is typed {{Object}} on the stack, so the
> call is rejected.
> These forms are unaffected because the receiver is already typed as the array:
> * {{a.clone()}} where {{a}} is a {{float[]}} or {{float[][]}} parameter or
> local
> * {{float[] b = a[0]; b.clone()}}
> * {{def b = a[0]; b.clone()}}
> h3. Workaround
> Assign the element to a local variable before calling {{clone()}}.
> h3. Affects
> 6.0.0, and current master (7.0.0-SNAPSHOT) and GROOVY_6_0_X.
> h3. Proposed fix
> In {{CheckcastReceiverExpression#getType()}}, keep the array receiver type
> (and so emit {{checkcast}}) when the target is a no-arg {{clone()}} on an
> array, instead of falling back to {{Object}}. Regression test:
> {{ArraysAndCollectionsSTCTest#testArrayCloneOfArrayElement}}, which also runs
> under static compilation via {{ArraysAndCollectionsStaticCompileTest}}.
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