add test case about explicitly capturing variable

Author: zhaohuiw42

clang/test/SemaCXX/uninitialized.cpp

@@ -892,10 +892,11 @@ namespace lambdas {
       return a1.x;
     });
     A a2([&] { return a2.x; }); // ok
-    A a3([=]{ return a3.x; }()); // expected-warning{{variable 'a3' is uninitialized when used within its own initialization}}
-    A a4([&]{ return a4.x; }()); // expected-warning{{variable 'a4' is uninitialized when used within its own initialization}}
-    A a5([&]{ return a5; }()); // expected-warning{{variable 'a5' is uninitialized when used within its own initialization}}
-    A a6([&]{ return a5.x; }()); // ok
+    A a3([=] { return a3.x; }()); // expected-warning{{variable 'a3' is uninitialized when used within its own initialization}}
+    A a4([&] { return a4.x; }()); // expected-warning{{variable 'a4' is uninitialized when used within its own initialization}}
+    A a5([&] { return a5; }()); // expected-warning{{variable 'a5' is uninitialized when used within its own initialization}}
+    A a6([&] { return a5.x; }()); // ok
+    A a7 = [&a7] { return a7; }(); // expected-warning{{variable 'a7' is uninitialized when used within its own initialization}}
   }
 }