UseForEachLoop - not to change in case of array assignment (#661)

* Test case

* insideInvalidAccess logic

Author: greg-at-moderne

src/main/java/org/openrewrite/staticanalysis/UseForEachLoop.java

@@ -258,6 +258,7 @@ private class ValidationVisitor extends JavaVisitor<Object> {
                 private final J collection;
                 private boolean valid = true;
                 private boolean insideValidAccess;
+                private boolean insideInvalidAccess;
 
                 public ValidationVisitor(String indexVarName, J collection) {
                     this.indexVarName = indexVarName;
@@ -308,6 +309,9 @@ public J visitArrayAccess(J.ArrayAccess arrayAccess, Object o) {
                         } else {
                             valid = false;
                         }
+                        if (insideInvalidAccess) {
+                            valid = false;
+                        }
 
                         J result = super.visitArrayAccess(arrayAccess, o);
                         insideValidAccess = wasInsideValidAccess;
@@ -316,6 +320,13 @@ public J visitArrayAccess(J.ArrayAccess arrayAccess, Object o) {
                     return super.visitArrayAccess(arrayAccess, o);
                 }
 
+                @Override
+                public J visitAssignment(J.Assignment assignment, Object o) {
+                    this.insideInvalidAccess = true;
+                    this.visit(assignment.getVariable(), o);
+                    this.insideInvalidAccess = false;
+                    return super.visitAssignment(assignment, o);
+                }
             }
 
             private class BodyTransformer extends JavaVisitor<Object> {

src/test/java/org/openrewrite/staticanalysis/UseForEachLoopTest.java

@@ -331,4 +331,22 @@ void test(CustomContainer container) {
           )
         );
     }
+
+    @Test
+    void noChangeWhenArrayAccessOnLeftSideOfAssignment() {
+        rewriteRun(
+          //language=java
+          java(
+            """
+            class Test {
+                void test(String[] names) {
+                    for (int i = 0; i < names.length; i++) {
+                        names[i] = "modified";
+                    }
+                }
+            }
+            """
+          )
+        );
+    }
 }