Paul King created GROOVY-7865:
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Summary: 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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