fix #17812 (repr fails to compile with ARC/ORC) (#17816)

tests/arc/t17812.nim

@@ -0,0 +1,29 @@
+discard """
+  targets: "c js"
+  matrix: "--gc:refc; --gc:arc"
+"""
+
+import std/times
+
+block: # bug #17812
+  block:
+    type
+      Task = object
+        cb: proc ()
+
+    proc hello() = discard
+
+
+    let t = Task(cb: hello)
+
+    doAssert t.repr.len > 0
+
+
+  block:
+    type MyObj = object
+      field: DateTime
+
+
+    proc `$`(o: MyObj): string = o.repr
+
+    doAssert ($MyObj()).len > 0