ref #14873 (#17644)

* ref #14873

* comment

* Update lib/core/locks.nim

tests/stdlib/tlocks.nim

@@ -1,10 +1,10 @@
 discard """
-  output: '''3'''
-  cmd: "nim $target --threads:on $options $file"
+  targets: "c cpp js"
+  matrix: "--threads:on"
 """
 
 #bug #6049
 import uselocks
 
 var m = createMyType[int]()
-echo $m.use()
+doAssert m.use() == 3

tests/stdlib/uselocks.nim

@@ -9,3 +9,7 @@ proc createMyType*[T]: MyType[T] =
 proc use* (m: var MyType): int =
   withLock m.lock:
     result = 3
+
+block:
+  var l: Lock
+  doAssert $l == "()"