(Hot) Fix issue 608 by disable migration of variables that are initialized by static methods

Author: MBoegers

src/main/java/org/openrewrite/java/migrate/lang/var/DeclarationCheck.java

@@ -18,6 +18,8 @@
 import org.openrewrite.Cursor;
 import org.openrewrite.java.tree.*;
 
+import javax.annotation.Nullable;
+
 import static java.util.Objects.requireNonNull;
 
 final class DeclarationCheck {
@@ -198,4 +200,30 @@ private static boolean isInsideInitializer(Cursor cursor, int nestedBlockLevel)
 
         return isInsideInitializer(requireNonNull(cursor.getParent()), nestedBlockLevel);
     }
+
+    /**
+     * Checks whether the initializer {@linkplain Expression} is a {@linkplain J.MethodInvocation} targeting a static method.
+     *
+     * @param initializer {@linkplain J.VariableDeclarations.NamedVariable#getInitializer()} value
+     * @return true iff is initialized by static method
+     */
+    public static boolean initializedByStaticMethod(@Nullable Expression initializer) {
+        if (initializer == null) {
+            return false;
+        }
+        initializer = initializer.unwrap();
+
+        if (!(initializer instanceof J.MethodInvocation)) {
+            // no MethodInvocation -> false
+            return false;
+        }
+
+        J.MethodInvocation invocation = (J.MethodInvocation) initializer;
+        if (invocation.getMethodType() == null) {
+            // not a static method -> false
+            return false;
+        }
+
+        return invocation.getMethodType().getFlags().contains(Flag.Static);
+    }
 }

src/main/java/org/openrewrite/java/migrate/lang/var/UseVarForObject.java

@@ -75,8 +75,10 @@ public J.VariableDeclarations visitVariableDeclarations(J.VariableDeclarations v
             boolean isPrimitive = DeclarationCheck.isPrimitive(vd);
             boolean usesGenerics = DeclarationCheck.useGenerics(vd);
             boolean usesTernary = DeclarationCheck.initializedByTernary(vd);
-            boolean usesArrayInitializer = vd.getVariables().get(0).getInitializer() instanceof J.NewArray;
-            if (isPrimitive || usesGenerics || usesTernary || usesArrayInitializer) {
+            Expression initializer = vd.getVariables().get(0).getInitializer();
+            boolean usesArrayInitializer = initializer instanceof J.NewArray;
+            boolean initializedByStaticMethod = DeclarationCheck.initializedByStaticMethod(initializer);
+            if (isPrimitive || usesGenerics || usesTernary || usesArrayInitializer || initializedByStaticMethod) {
                 return vd;
             }
 

src/test/java/org/openrewrite/java/migrate/lang/var/UseVarForObjectsTest.java

@@ -270,6 +270,7 @@ void m() {
             }
 
             @Test
+            @Disabled("in favor to https://github.com/openrewrite/rewrite-migrate-java/issues/608 we skip all static methods ATM")
             void staticMethods() {
                 //language=java
                 rewriteRun(
@@ -345,10 +346,7 @@ class NotApplicable {
         @Test
         @Issue("https://github.com/openrewrite/rewrite-migrate-java/issues/608")
         void genericTypeInStaticMethod() {
-            /*
-                         * This can be migrated from `String string = Global.cast(o)` to `var string = Global.<String>cast(o)`.
-                         * But we decided to not migrate, because it is very unconventional Java.
-            */
+            // ATM the recipe skips all static method initialized variables
             rewriteRun(
               java(
                 """