fixes #2470, fixes #1354

tests/types/temptyseqs.nim

@@ -1,5 +1,13 @@
 discard """
-  output: "1"
+  output: '''1
+foo
+bar
+baz
+foo
+bar
+baz
+yes
+no'''
 """
 
 # bug #1708
@@ -24,3 +32,59 @@ when true:
 const foo2: seq[string] = @[]
 
 echo foo[0][0][0]
+
+proc takeEmpty(x: openArray[string] = []) = discard
+takeEmpty()
+takeEmpty([])
+
+proc takeEmpty2(x: openArray[string] = @[]) = discard
+takeEmpty2()
+takeEmpty2([])
+takeEmpty2(@[])
+
+#takeEmpty2([nil])
+
+#rawMessage(errExecutionOfProgramFailed, [])
+
+# bug #2470
+const
+  stuff: seq[string] = @[]
+
+for str in stuff:
+  echo "str=", str
+
+# bug #1354
+proc foo4[T](more: seq[T] = @[]) =
+  var more2 = more
+
+foo4[int]()
+
+proc maino: int =
+  var wd: cstring = nil
+  inc result
+
+discard maino()
+
+proc varargso(a: varargs[string]) =
+  for x in a:
+    echo x
+
+varargso(["foo", "bar", "baz"])
+varargso("foo", "bar", "baz")
+
+
+type
+  Flago = enum
+    tfNeedsInit, tfNotNil
+
+var s: set[Flago] = {tfNeedsInit}
+
+if {tfNeedsInit, tfNotNil} * s != {}:
+  echo "yes"
+else:
+  echo "no"
+
+if {tfNeedsInit, tfNotNil} * s <= {tfNotNil}:
+  echo "yes"
+else:
+  echo "no"