Var Recipes error on Unbounded or Generic Type Parameter

[MBoegers]

What version of OpenRewrite are you using?

I am using Moderne.io, current.

How are you running OpenRewrite?

I am using Moderne.io and triggered UseVar Recipe.
And discovered the problem in various Spring Projects like spring-shell

What is the smallest, simplest way to reproduce the problem?

class A {
    static <T> void generic() {
        List<T> lst = new ArrayList<>();
    }
    void unbound() {
        List<?> lst = new ArrayList<>();
    }
    void inception() {
        List<List<Object>> lst = new ArrayList<>();
    }
}

What did you expect to see?

class A {
  static <T> void generic() {
      var lst = new ArrayList<T>();
  }
  void unbound() {
      var lst = new ArrayList<>();
  }
  void inception() {
      var lst = new ArrayList<List<Object>>();
  }
}

What did you see instead?

Generic

class org.openrewrite.java.tree.JavaType$GenericTypeVariable cannot be cast to class org.openrewrite.java.tree.JavaType$Class (org.openrewrite.java.tree.JavaType$GenericTypeVariable and org.openrewrite.java.tree.JavaType$Class are in unnamed module of loader 'app')

Unbound

class org.openrewrite.java.tree.JavaType$GenericTypeVariable cannot be cast to class org.openrewrite.java.tree.JavaType$Class (org.openrewrite.java.tree.JavaType$GenericTypeVariable and org.openrewrite.java.tree.JavaType$Class are in unnamed module of loader 'app')

Inception

class org.openrewrite.java.tree.JavaType$Parameterized cannot be cast to class org.openrewrite.java.tree.JavaType$Class (org.openrewrite.java.tree.JavaType$Parameterized and org.openrewrite.java.tree.JavaType$Class are in unnamed module of loader 'app')

What is the full stack trace of any errors you encountered?

Generic

java.lang.ClassCastException: class org.openrewrite.java.tree.JavaType$GenericTypeVariable cannot be cast to class org.openrewrite.java.tree.JavaType$Class (org.openrewrite.java.tree.JavaType$GenericTypeVariable and org.openrewrite.java.tree.JavaType$Class are in unnamed module of loader 'app')
org.openrewrite.java.migrate.lang.var.UseVarForGenericsConstructors$UseVarForGenericsVisitor.lambda$transformToVar$0(UseVarForGenericsConstructors.java:121)
java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
java.base/java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:992)
java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
...

Unbound

java.lang.ClassCastException: class org.openrewrite.java.tree.JavaType$GenericTypeVariable cannot be cast to class org.openrewrite.java.tree.JavaType$Class (org.openrewrite.java.tree.JavaType$GenericTypeVariable and org.openrewrite.java.tree.JavaType$Class are in unnamed module of loader 'app')
org.openrewrite.java.migrate.lang.var.UseVarForGenericsConstructors$UseVarForGenericsVisitor.lambda$transformToVar$0(UseVarForGenericsConstructors.java:121)
java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
java.base/java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:992)
java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
...

Inception

java.lang.ClassCastException: class org.openrewrite.java.tree.JavaType$Parameterized cannot be cast to class org.openrewrite.java.tree.JavaType$Class (org.openrewrite.java.tree.JavaType$Parameterized and org.openrewrite.java.tree.JavaType$Class are in unnamed module of loader 'app')
org.openrewrite.java.migrate.lang.var.UseVarForGenericsConstructors$UseVarForGenericsVisitor.lambda$transformToVar$0(UseVarForGenericsConstructors.java:121)
java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
java.base/java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:992)
java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
...

Are you interested in contributing a fix to OpenRewrite?

yup.

[MBoegers]

It is fixed in #259, bounded generics e.q. List<? extends String> are skipped because I am unable to parse Bounds as Expressions.

[joanvr]

Thank you very much for your contribution @MBoegers! Let's follow the conversation in the PR