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https://issues.apache.org/jira/browse/GROOVY-7865?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15346164#comment-15346164
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ASF GitHub Bot commented on GROOVY-7865:
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GitHub user paulk-asert opened a pull request:
https://github.com/apache/groovy/pull/353
GROOVY-7865: Better error message and earlier detection of Generics errors
reworked version
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/paulk-asert/groovy groovy7865b
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/groovy/pull/353.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #353
----
commit 2b8d488f0519add9aef73f59d998769f8808cbfe
Author: paulk <pa...@asert.com.au>
Date: 2016-06-17T08:38:25Z
GROOVY-7865: Better error message in the presence of Generics arity errors
(spike)
----
> Better error message in the presence of Generics arity errors
> -------------------------------------------------------------
>
> Key: GROOVY-7865
> URL: https://issues.apache.org/jira/browse/GROOVY-7865
> Project: Groovy
> Issue Type: Bug
> Affects Versions: 2.4.7
> Reporter: Paul King
>
> Currently there are many places in the codebase which make assumptions that
> they are working with valid generics information. Generics information is
> checked but not until the classgen phase. Consequently, we get a very
> uninformative ArrayIndexOutOfBoundsException from the compiler - either along
> with or instead of the subsequent generics checking. These are all examples
> which should fail compilation since I have intentionally tried to instantiate
> the generics type with an incorrect number of parameters. It is just the
> error message which is not currently useful and masking the subsequent
> message that would occur had not the exception got in the way.
> Example with TraitComposer:
> {code}
> class MyNames implements Queue<Integer, String> { }
> // java.lang.ArrayIndexOutOfBoundsException: 1
> // TraitComposer calls GenericsUtils.parameterizeType()
> // which calls GenericsUtils.createGenericsSpec()
> {code}
> Example with StaticTypeCheckingVisitor:
> {code}
> @CompileStatic
> def foo() {
> List<String> ss = new LinkedList<Integer, String>()
> }
> // => java.lang.ArrayIndexOutOfBoundsException: 1
> {code}
> Example with Verifier:
> {code}
> class MyNames extends Queue<Integer, String> { }
> {code}
> which gives
> {noformat}
> 2 compilation errors:
> The class java.util.Queue refers to the class java.util.Queue and uses 2
> parameters, but the referred class needs 1
> at line: 5, column: 23
> Exception thrown
> java.lang.ArrayIndexOutOfBoundsException: 1
> at
> org.codehaus.groovy.ast.tools.GenericsUtils.createGenericsSpec(GenericsUtils.java:410)
> {noformat}
> So we get one error from the generics checking but then continue on to the
> Verifier.
> I suspect the fix for this is to move just the arity checking part of that
> visitor to an earlier phase.
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