Fix Nim's issue #13899 using #14723 and add tests. (#104)

chronos.nimble

@@ -1,5 +1,5 @@
 packageName   = "chronos"
-version       = "2.4.0"
+version       = "2.4.1"
 author        = "Status Research & Development GmbH"
 description   = "Chronos"
 license       = "Apache License 2.0 or MIT"

chronos/asyncmacro2.nim

@@ -203,6 +203,9 @@ proc asyncSingleProc(prc: NimNode): NimNode {.compileTime.} =
                                     futureVarIdents)
   # don't do anything with forward bodies (empty)
   if procBody.kind != nnkEmpty:
+    # fix #13899, `defer` should not escape its original scope
+    procBody = newStmtList(newTree(nnkBlockStmt, newEmptyNode(), procBody))
+
     procBody.add(createFutureVarCompletions(futureVarIdents, nil))
 
     if not subtypeIsVoid:

tests/testbugs.nim

@@ -73,6 +73,31 @@ suite "Asynchronous issues test suite":
     await sleepAsync(100.milliseconds)
     result = (checkstr == "FooBarBaz")
 
+  proc testDefer(): Future[bool] {.async.} =
+    proc someConnect() {.async.} =
+      await sleepAsync(100.milliseconds)
+
+    proc someClose() {.async.} =
+      await sleepAsync(100.milliseconds)
+
+    proc testFooFails(): Future[bool] {.async.} =
+      await someConnect()
+      defer:
+        await someClose()
+        result = true
+
+    proc testFooSucceed(): Future[bool] {.async.} =
+      try:
+        await someConnect()
+      finally:
+        await someClose()
+        result = true
+
+    let r1 = await testFooFails()
+    let r2 = await testFooSucceed()
+
+    result = r1 and r2
+
   test "Issue #6":
     check waitFor(issue6()) == true
 
@@ -84,3 +109,6 @@ suite "Asynchronous issues test suite":
 
   test "Multiple await on single future test [Nim's issue #13889]":
     check waitFor(testMultipleAwait()) == true
+
+  test "Defer for asynchronous procedures test [Nim's issue #13899]":
+    check waitFor(testDefer()) == true