fixes #2355

compiler/semexprs.nim

@@ -1904,7 +1904,8 @@ proc checkInitialized(n: PNode, ids: IntSet, info: TLineInfo) =
         of nkOfBranch, nkElse: checkInitialized(lastSon(n.sons[i]), ids, info)
         else: internalError(info, "checkInitialized")
   of nkSym:
-    if tfNeedsInit in n.sym.typ.flags and n.sym.name.id notin ids:
+    if {tfNotNil, tfNeedsInit} * n.sym.typ.flags != {} and
+        n.sym.name.id notin ids:
       message(info, errGenerated, "field not initialized: " & n.sym.name.s)
   else: internalError(info, "checkInitialized")
 

tests/notnil/tnotnil_in_objconstr.nim

@@ -0,0 +1,14 @@
+discard """
+  errormsg: "field not initialized: bar"
+  line: "13"
+"""
+
+# bug #2355
+type
+  Foo = object
+    foo: string not nil
+    bar: string not nil
+
+# Create instance without initializaing the `bar` field
+var f = Foo(foo: "foo")
+echo f.bar.isNil # true