the new blocks without 'do' produce compatible AST with 'do blocks'

compiler/parser.nim

@@ -1172,7 +1172,7 @@ proc parseMacroColon(p: var TParser, x: PNode): PNode =
     result = makeCall(result)
     getTok(p)
     skipComment(p, result)
-    let stmtList = newNodeP(nkStmtList, p)
+    var stmtList = newNodeP(nkStmtList, p)
     if p.tok.tokType notin {tkOf, tkElif, tkElse, tkExcept}:
       let body = parseStmt(p)
       stmtList.add body
@@ -1202,9 +1202,9 @@ proc parseMacroColon(p: var TParser, x: PNode): PNode =
       if b.kind == nkElse: break
     if stmtList.len == 1 and stmtList[0].kind == nkStmtList:
       # to keep backwards compatibility (see tests/vm/tstringnil)
-      result.add stmtList[0]
-    else:
-      result.add stmtList
+      stmtList = stmtList[0]
+    result.add newProcNode(nkDo, stmtList.info, stmtList,
+                           params = emptyNode, pragmas = emptyNode)
 
 proc parseExprStmt(p: var TParser): PNode =
   #| exprStmt = simpleExpr

tests/closure/tdonotation.nim

@@ -1,8 +1,10 @@
 discard """
 output: '''
 click at 10,20
+lost focus 1
 lost focus 2
 registered handler for UserEvent 1
+registered handler for UserEvent 2
 registered handler for UserEvent 3'''
 """
 
@@ -27,10 +29,8 @@ var b = Button()
 b.onClick do (e: Event):
   echo "click at ", e.x, ",", e.y
 
-when false:
-  # this syntax doesn't work yet
-  b.onFocusLost:
-    echo "lost focus 1"
+b.onFocusLost:
+  echo "lost focus 1"
 
 b.onFocusLost do:
   echo "lost focus 2"
@@ -38,10 +38,8 @@ b.onFocusLost do:
 b.onUserEvent("UserEvent 1") do:
   discard
 
-when false:
-  # this syntax doesn't work yet
-  b.onUserEvent("UserEvent 2"):
-    discard
+b.onUserEvent("UserEvent 2"):
+  discard
 
 b.onUserEvent("UserEvent 3", () => echo "event 2")