report 'Missing return' for closure if there is explicit generic in expected type

plugins/groovy/src/org/jetbrains/plugins/groovy/codeInspection/noReturnMethod/MissingReturnInspection.java

@@ -18,9 +18,7 @@ package org.jetbrains.plugins.groovy.codeInspection.noReturnMethod;
 import com.intellij.codeInspection.ProblemsHolder;
 import com.intellij.openapi.util.Ref;
 import com.intellij.openapi.util.TextRange;
-import com.intellij.psi.PsiElement;
-import com.intellij.psi.PsiElementVisitor;
-import com.intellij.psi.PsiType;
+import com.intellij.psi.*;
 import org.jetbrains.annotations.Nls;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
@@ -71,6 +69,10 @@ public class MissingReturnInspection extends GroovySuppressableInspectionTool {
     public static ReturnStatus getReturnStatus(PsiElement subject) {
       if (subject instanceof GrClosableBlock) {
         final PsiType inferredReturnType = GroovyExpectedTypesProvider.getExpectedClosureReturnType((GrClosableBlock)subject);
+        if (inferredReturnType instanceof PsiClassType) {
+          PsiClass resolved = ((PsiClassType)inferredReturnType).resolve();
+          if (resolved != null && !(resolved instanceof PsiTypeParameter)) return mustReturnValue;
+        }
         return inferredReturnType != null && inferredReturnType != PsiType.VOID ? shouldReturnValue : shouldNotReturnValue;
       }
       else if (subject instanceof GrMethod) {

plugins/groovy/test/org/jetbrains/plugins/groovy/lang/MissingReturnTest.groovy

@@ -41,6 +41,7 @@ public class MissingReturnTest extends LightCodeInsightFixtureTestCase {
   public void testImplicitReturnNull() throws Throwable {doTest();}
   public void testMissingReturnInClosure() {doTest();}
   public void testFinally() {doTest();}
+  public void testClosureWithExplicitExpectedType() {doTest()}
 
   private void doTest() {
     myFixture.enableInspections(new MissingReturnInspection());

plugins/groovy/testdata/highlighting/missingReturn/ClosureWithExplicitExpectedType.groovy

@@ -0,0 +1,19 @@
+def foo(Closure<String> c) {
+  return c().substring(1)
+}
+
+foo {
+  print 2
+<warning descr="Not all execution paths return a value">}</warning>
+
+foo {
+  's'
+}
+
+foo {
+  if (a) 's'
+<warning descr="Not all execution paths return a value">}</warning>
+
+foo {
+  if (a) 'a' else 'b'
+}