[jira] [Commented] (GROOVY-10054) STC: Cannot infer lambda parameter types for a Stream Collector in a generic method
[
https://issues.apache.org/jira/browse/GROOVY-10054?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=17332459#comment-17332459
]
Eric Milles commented on GROOVY-10054:
--
The static type checker visits the non-closure method arguments before
selecting the method, because it needs type information to choose the best fit.
So, to work around this, you can assign the collector to a local variable
first, like this:
{code:groovy}
Map> group(Set set) {
Collector>> grouping =
Collectors.groupingBy(named -> named.getName())
set.stream().collect(grouping);
}
{code}
Not ideal, but should pass STC until this issue can be resolved.
> STC: Cannot infer lambda parameter types for a Stream Collector in a generic
> method
> ---
>
> Key: GROOVY-10054
> URL: https://issues.apache.org/jira/browse/GROOVY-10054
> Project: Groovy
> Issue Type: Bug
> Components: Static Type Checker
> Environment: OpenJDK8
>Reporter: Lyuben Atanasov
>Assignee: Eric Milles
>Priority: Major
>
> This is a follow-up to GROOVY-10049. After the issue there had been fixed I
> was able to progress further with a chain of Stream method calls. However,
> the fix doesn't seem to cover the following case:
> {code}
> import java.util.stream.Collectors;
> class Test {
> static interface Named {
> String getName();
> }
>Map> group(Set namedObjects) {
> return namedObjects.stream()
> .collect(Collectors.groupingBy(named ->
> named.getName()));
> }
>
> }
> {code}
> With static type checking enabled, an error is produced:
> {noformat}
> Script_ce61a645759c941d687680111f9bedbd.groovy: 11: [Static type checking] -
> Cannot find matching method java.lang.Object#getName(). Please check if the
> declared type is correct and if the method exists.
> @ line 11, column 44.
>ollectors.groupingBy(named -> named.getN
> {noformat}
> The difference between this issue and GROOVY-10049 is that the lambda passed
> here is not directly assigned to a Stream method. Of course, the issue is
> probably not limited to Collectors, but this is how I am able to reproduce it.
> I've tested this against
> https://github.com/apache/groovy/commit/e07f0112c5eff8d9c6828bd0ddb69e4b7f7cc1d6
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[jira] [Commented] (GROOVY-10054) STC: Cannot infer lambda parameter types for a Stream Collector in a generic method
[
https://issues.apache.org/jira/browse/GROOVY-10054?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=17330861#comment-17330861
]
Lyuben Atanasov commented on GROOVY-10054:
--
I have tried this without the method being generic as well. The following code
still fails static type checking:
{code}
static interface Named {
String getName();
}
Map> group(Set namedObjects) {
return namedObjects.stream()
.collect(Collectors.groupingBy(named ->
named.getName()));
}
}
{code}
> STC: Cannot infer lambda parameter types for a Stream Collector in a generic
> method
> ---
>
> Key: GROOVY-10054
> URL: https://issues.apache.org/jira/browse/GROOVY-10054
> Project: Groovy
> Issue Type: Bug
> Components: Static Type Checker
> Environment: OpenJDK8
>Reporter: Lyuben Atanasov
>Priority: Major
>
> This is a follow-up to GROOVY-10049. After the issue there had been fixed I
> was able to progress further with a chain of Stream method calls. However,
> the fix doesn't seem to cover the following case:
> {code}
> import java.util.stream.Collectors;
> class Test {
> static interface Named {
> String getName();
> }
>Map> group(Set namedObjects) {
> return namedObjects.stream()
> .collect(Collectors.groupingBy(named ->
> named.getName()));
> }
>
> }
> {code}
> With static type checking enabled, an error is produced:
> {noformat}
> Script_ce61a645759c941d687680111f9bedbd.groovy: 11: [Static type checking] -
> Cannot find matching method java.lang.Object#getName(). Please check if the
> declared type is correct and if the method exists.
> @ line 11, column 44.
>ollectors.groupingBy(named -> named.getN
> {noformat}
> The difference between this issue and GROOVY-10049 is that the lambda passed
> here is not directly assigned to a Stream method. Of course, the issue is
> probably not limited to Collectors, but this is how I am able to reproduce it.
> I've tested this against
> https://github.com/apache/groovy/commit/e07f0112c5eff8d9c6828bd0ddb69e4b7f7cc1d6
--
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