closes #14216; add testcase (#20733)

tests/effects/teffectsmisc.nim

@@ -0,0 +1,39 @@
+discard """
+  output: '''
+printing from adder
+'''
+"""
+
+import std/sugar
+
+block:
+  proc makeAdder(a: int): (int) -> void =
+    proc discard_adder(x: int) {.closure.} =
+      discard a + x
+
+    proc echo_adder(x: int) {.closure.} =
+      echo("printing from adder")
+
+    if a > 0:
+      discard_adder
+    else:
+      echo_adder
+
+  let newAdder = makeAdder(0)
+  newAdder(5)
+
+block:
+  proc makeAdder(a: int): (int) -> void =
+    proc discard_adder(x: int) {.closure.} =
+      discard a + x
+
+    proc echo_adder(x: int) {.closure.} =
+      echo("printing from adder")
+
+    if a > 0:
+      echo_adder
+    else:
+      discard_adder
+
+  let newAdder = makeAdder(0)
+  newAdder(5)