UseVarForGenericMethodInvocations fails with nested generics

[jagodevreede]

What version of OpenRewrite are you using?

I am using

• Maven plugin v6.18.0
• rewrite-migrate-java 3.18.0

How are you running OpenRewrite?

I am using the Maven plugin, and my project is a mutli module project.

<project>
  <build>
    <plugins>
      <plugin>
        <groupId>org.openrewrite.maven</groupId>
        <artifactId>rewrite-maven-plugin</artifactId>
        <version>6.18.0</version>
        <configuration>
          <exportDatatables>true</exportDatatables>
          <activeRecipes>
            <recipe>org.openrewrite.java.migrate.lang.var.UseVarForGenericMethodInvocations</recipe>
          </activeRecipes>
        </configuration>
        <dependencies>
          <dependency>
            <groupId>org.openrewrite.recipe</groupId>
            <artifactId>rewrite-migrate-java</artifactId>
            <version>3.18.0</version>
          </dependency>
        </dependencies>
      </plugin>
    </plugins>
  </build>
</project>

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

class A {
    private void dostuff() {
        List<String> strs = Collections.synchronizedList(new ArrayList<>());
        strs.forEach(this::soString);
    }

    public void soString(String s) {
        System.out.println(s);
    }
}

What did you expect to see?

class A {
    private void dostuff() {
        var strs = Collections.synchronizedList(new ArrayList<String>());
        strs.forEach(this::soString);
    }

    public void soString(String s) {
        System.out.println(s);
    }
}

What did you see instead?

class A {
    private void dostuff() {
        var strs = Collections.synchronizedList(new ArrayList<>());
        strs.forEach(this::soString);
    }

    public void soString(String s) {
        System.out.println(s);
    }
}

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

Compiler error: incompatible types: invalid method reference
[ERROR] incompatible types: java.lang.Object cannot be converted to java.lang.String

Are you interested in contributing a fix to OpenRewrite?

Sure, I'll try and create a unit test for this as a starter and see from there on

[timtebeek]

Hey thanks for the clear report and offer to help! Good to see this logged here.

[timtebeek]

Here's a quick attempt at fixing this issue:

• Fix UseVarForGenericMethodInvocations for nested generics with diamond operators #863

@MBoegers was involved with the original recipe, so I'll let him review