IDEA-135846 Dfa should warn about qualifiers in method references

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

@@ -690,6 +690,21 @@ public class ControlFlowAnalyzer extends JavaElementVisitor {
     finishElement(switchStmt);
   }
 
+  @Override
+  public void visitMethodReferenceExpression(PsiMethodReferenceExpression expression) {
+    startElement(expression);
+
+    PsiExpression qualifier = expression.getQualifierExpression();
+    if (qualifier != null) {
+      qualifier.accept(this);
+      addInstruction(new FieldReferenceInstruction(qualifier, "Method reference qualifier"));
+    }
+
+    addInstruction(new PushInstruction(myFactory.createTypeValue(expression.getFunctionalInterfaceType(), Nullness.NOT_NULL), expression));
+
+    finishElement(expression);
+  }
+
   @Override public void visitSynchronizedStatement(PsiSynchronizedStatement statement) {
     startElement(statement);