don't blink with pure contract on gutter when starting to write a method

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/PurityInference.java

@@ -58,6 +58,7 @@ public class PurityInference {
     if (body == null) return false;
 
     final Ref<Boolean> impureFound = Ref.create(false);
+    final Ref<Boolean> hasReturns = Ref.create(false);
     final List<PsiMethodCallExpression> calls = ContainerUtil.newArrayList();
     body.accept(new JavaRecursiveElementWalkingVisitor() {
       @Override
@@ -68,6 +69,14 @@ public class PurityInference {
         super.visitAssignmentExpression(expression);
       }
 
+      @Override
+      public void visitReturnStatement(PsiReturnStatement statement) {
+        if (statement.getReturnValue() != null) {
+          hasReturns.set(true);
+        }
+        super.visitReturnStatement(statement);
+      }
+
       @Override
       public void visitPrefixExpression(PsiPrefixExpression expression) {
         if (isMutatingOperation(expression.getOperationTokenType()) && !isLocalVarReference(expression.getOperand())) {
@@ -95,7 +104,7 @@ public class PurityInference {
       }
     });
 
-    if (impureFound.get() || calls.size() > 1) return false;
+    if (impureFound.get() || calls.size() > 1 || !hasReturns.get()) return false;
     if (calls.isEmpty()) return true;
 
     final PsiMethod called = calls.get(0).resolveMethod();

java/java-tests/testSrc/com/intellij/codeInspection/PurityInferenceFromSourceTest.groovy

@@ -120,6 +120,15 @@ int smthPure() { return 3; }
 """
   }
 
+  public void "test don't analyze methods without returns"() {
+    assertPure false, """
+Object method() {
+    smthPure();
+}
+int smthPure() { return 3; }
+"""
+  }
+
   private void assertPure(boolean expected, String classBody) {
     def clazz = myFixture.addClass("final class Foo { $classBody }")
     assert expected == PurityInference.inferPurity(clazz.methods[0])