Make use of used in unittest (#5410)

tests/pragmas/tused.nim

@@ -1,13 +1,35 @@
 discard """
-  output: '''8'''
+  nimout: '''
+compile start
+tused.nim(15, 8) Hint: 'tused.echoSub(a: int, b: int)' is declared but not used [XDeclaredButNotUsed]
+compile end'''
+  output: "8\n8"
 """
 
-template implementArithOps(T) =
+static:
+  echo "compile start"
+
+template implementArithOpsOld(T) =
+  proc echoAdd(a, b: T) =
+    echo a + b
+  proc echoSub(a, b: T) =
+    echo a - b
+
+template implementArithOpsNew(T) =
   proc echoAdd(a, b: T) {.used.} =
     echo a + b
   proc echoSub(a, b: T) {.used.} =
     echo a - b
 
-# no warning produced for the unused 'echoSub'
-implementArithOps(int)
-echoAdd 3, 5
+block:
+  # should produce warning for the unused 'echoSub'
+  implementArithOpsOld(int)
+  echoAdd 3, 5
+
+block:
+  # no warning produced for the unused 'echoSub'
+  implementArithOpsNew(int)
+  echoAdd 3, 5
+
+static:
+  echo "compile end"