IDEA-177330 @CompileStatic multiple assignment in variable definition should be red

plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/lang/psi/impl/statements/typedef/members/GrMethodBaseImpl.java

@@ -230,7 +230,7 @@ public abstract class GrMethodBaseImpl extends GrStubElementBase<GrMethodStub> i
       if (block != null) {
         PsiType inferred = GroovyPsiManager.inferType(method, new MethodTypeInferencer(block));
         if (inferred != null) {
-          if (nominal == null || nominal.isAssignableFrom(inferred)) {
+          if (nominal == null || (nominal.isAssignableFrom(inferred) && !inferred.equals(PsiType.NULL))) {
             return inferred;
           }
         }

plugins/groovy/test/org/jetbrains/plugins/groovy/lang/resolve/TypeInferenceTest.groovy

@@ -709,6 +709,24 @@ def foo(List list) {
 ''', 'java.util.List<java.util.List>')
   }
 
+  void testReturnNullWithGeneric() {
+    doTest('''
+     import groovy.transform.CompileStatic
+
+    @CompileStatic
+    class SomeClass {
+      protected List foo(String text) {
+        return null
+      }
+
+      def bar() {
+        fo<caret>o("")
+      }
+    }
+  }
+''', 'java.util.List')
+  }
+
 
   void testClassExpressions() {
     doExprTest 'String[]', 'java.lang.Class<java.lang.String[]>'