no warning for assignment to dereferenced receiver (#2809)

Author: stuartcarnie

src/com/goide/inspections/GoAssignmentToReceiverInspection.java

@@ -19,6 +19,7 @@
 import com.goide.psi.GoPointerType;
 import com.goide.psi.GoReceiver;
 import com.goide.psi.GoReferenceExpression;
+import com.goide.psi.GoUnaryExpr;
 import com.goide.psi.GoVisitor;
 import com.intellij.codeInsight.highlighting.ReadWriteAccessDetector;
 import com.intellij.codeInspection.LocalInspectionToolSession;
@@ -41,6 +42,13 @@ public void visitReferenceExpression(@NotNull GoReferenceExpression o) {
           if (resolve instanceof GoReceiver) {
             String message = "Assignment to method receiver doesn't propagate to other calls";
             if (((GoReceiver)resolve).getType() instanceof GoPointerType) {
+              if (o.getParent() instanceof GoUnaryExpr) {
+                GoUnaryExpr p = (GoUnaryExpr)o.getParent();
+                if (p.getMul() != null) {
+                  // pointer dereference
+                  return;
+                }
+              }
               message = "Assignment to method receiver propagates only to callees but not to callers";
             }
             holder.registerProblem(o, message, WEAK_WARNING);

tests/com/goide/inspections/GoAssignmentToReceiverInspectionTest.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2013-2016 Sergey Ignatov, Alexander Zolotov, Florin Patan
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.goide.inspections;
+
+import com.goide.GoCodeInsightFixtureTestCase;
+
+public class GoAssignmentToReceiverInspectionTest extends GoCodeInsightFixtureTestCase {
+
+  @Override
+  public void setUp() throws Exception {
+    super.setUp();
+    myFixture.enableInspections(GoAssignmentToReceiverInspection.class);
+  }
+
+  public void testDoesNotPropagateToOtherCallsForNonPointerReceiver() {
+    doTest("func (r MyType) foo() { <weak_warning descr=\"Assignment to method receiver doesn't propagate to other calls\">r<caret></weak_warning> = 0 }");
+  }
+
+  public void testDoesNotPropagateToOtherCallsForPointerReceiver() {
+    doTest("func (r *MyType) foo() { <weak_warning descr=\"Assignment to method receiver propagates only to callees but not to callers\">r<caret></weak_warning> = 0 }");
+  }
+
+  public void testNoFixForDereferencedPointerReceiver() {
+    doTest("func (r *MyType) foo() { *r<caret> = 0 }");
+  }
+
+  private void doTest(String code) {
+    myFixture.configureByText("a.go", "package main; type MyType int; " + code);
+    myFixture.checkHighlighting();
+  }
+}