remove {.this.} pragma, deprecated since 0.19 (#20201)

Co-authored-by: Andreas Rumpf <rumpf_a@web.de>

tests/misc/tcsharpusingstatement.nim

@@ -0,0 +1,88 @@
+discard """
+  output: "Using test.Closing test."
+"""
+
+import
+  macros
+
+# This macro mimics the using statement from C#
+#
+# It's kept only as a test for the macro system
+# Nim's destructors offer a mechanism for automatic
+# disposal of resources.
+#
+macro autoClose(args: varargs[untyped]): untyped =
+  let e = callsite()
+  if e.len != 3:
+    error "Using statement: unexpected number of arguments. Got " &
+      $e.len & ", expected: 1 or more variable assignments and a block"
+
+  var args = e
+  var body = e[2]
+
+  var
+    variables : seq[NimNode]
+    closingCalls : seq[NimNode]
+
+  newSeq(variables, 0)
+  newSeq(closingCalls, 0)
+
+  for i in countup(1, args.len-2):
+    if args[i].kind == nnkExprEqExpr:
+      var varName = args[i][0]
+      var varValue = args[i][1]
+
+      var varAssignment = newNimNode(nnkIdentDefs)
+      varAssignment.add(varName)
+      varAssignment.add(newNimNode(nnkEmpty)) # empty means no type
+      varAssignment.add(varValue)
+      variables.add(varAssignment)
+
+      closingCalls.add(newCall(newIdentNode("close"), varName))
+    else:
+      error "Using statement: Unexpected expression. Got " &
+        $args[i].kind & " instead of assignment."
+
+  var varSection = newNimNode(nnkVarSection)
+  varSection.add(variables)
+
+  var finallyBlock = newNimNode(nnkStmtList)
+  finallyBlock.add(closingCalls)
+
+  # XXX: Use a template here once getAst is working properly
+  var targetAst = parseStmt"""block:
+    var
+      x = foo()
+      y = bar()
+
+    try:
+      body()
+
+    finally:
+      close x
+      close y
+  """
+
+  targetAst[0][1][0] = varSection
+  targetAst[0][1][1][0] = body
+  targetAst[0][1][1][1][0] = finallyBlock
+
+  result = targetAst
+
+type
+  TResource* = object
+    field*: string
+
+proc openResource(param: string): TResource =
+  result.field = param
+
+proc close(r: var TResource) =
+  write(stdout, "Closing " & r.field & ".")
+
+proc use(r: var TResource) =
+  write(stdout, "Using " & r.field & ".")
+
+autoClose(r = openResource("test")):
+  use r
+
+write stdout, "\n"