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https://issues.apache.org/jira/browse/GROOVY-10960?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Paul King updated GROOVY-10960:
-------------------------------
    Description: 
Following on from GROOVY-10953 we could consider reporting an error where the 
RHS of a range expression has a known size and that size is smaller than the 
number of variables in the multi-assignment, e.g.:

{code}
def (a,b,c) = 1..2
{code}

For static Groovy, after GROOVY-10953, and always for dynamic Groovy, {{c}} 
would be null.
We can exclude this behavior and instead provide an error by adding an 
additional check.


  was:
The following code runs fine without {{TypeChecked}} but fails in static 
checking mode.
{code}
@groovy.transform.TypeChecked
def method() {
    def (x, y, z) = 1..3
    assert "$x $y $z" == '1 2 3'
}

method()
{code}
The error is:
{noformat}
[Static type checking] - Multiple assignments without list or tuple on the 
right-hand side are unsupported in static type checking mode
{noformat}

The workaround is to replace the range on the RHS of the multi-assignment with 
a list:
{code}
  def (x, y, z) = [1, 2, 3]
{code}
But since we know the range expression, we can do further checking.


> For multi-assignment type checking of Range expressions, consider reporting 
> an error for cases which have a known size
> ----------------------------------------------------------------------------------------------------------------------
>
>                 Key: GROOVY-10960
>                 URL: https://issues.apache.org/jira/browse/GROOVY-10960
>             Project: Groovy
>          Issue Type: Improvement
>            Reporter: Paul King
>            Assignee: Paul King
>            Priority: Major
>             Fix For: 5.0.0-alpha-1
>
>
> Following on from GROOVY-10953 we could consider reporting an error where the 
> RHS of a range expression has a known size and that size is smaller than the 
> number of variables in the multi-assignment, e.g.:
> {code}
> def (a,b,c) = 1..2
> {code}
> For static Groovy, after GROOVY-10953, and always for dynamic Groovy, {{c}} 
> would be null.
> We can exclude this behavior and instead provide an error by adding an 
> additional check.



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