work around Nim 2.0.10 issue

json_rpc/private/server_handler_wrapper.nim

@@ -41,7 +41,7 @@ template rpc_isOptional[T](_: options.Option[T]): bool = true
 # Run time helpers
 # ------------------------------------------------------------------------------
 
-proc unpackArg(args: JsonString, argName: string, argType: type): argType
+func unpackArg(args: JsonString, argName: string, argType: type): argType
                 {.gcsafe, raises: [JsonRpcError].} =
   ## This where input parameters are decoded from JSON into
   ## Nim data types
@@ -89,12 +89,25 @@ template expectOptionalParamsLen(params: RequestParamsRx,
 
 template expectParamsLen(params: RequestParamsRx, length: static[int]) =
   ## Make sure positional params meets the handler expectation
-  let
-    expected = "Expected " & $length & " Json parameter(s) but got "
 
-  if params.positional.len != length:
-    raise newException(RequestDecodeError,
-      expected & $params.positional.len)
+  when (NimMajor, NimMinor) < (2, 2):
+    # https://github.com/nim-lang/Nim/issues/24228 in Nim 2.0.10 (not 2.0.8 and
+    # not 2.2.x) means that `expectParamsLen` in a Chronos async context, along
+    # with `{.compileTime.}` `$` overloads for `int`, `uint64`, and `int64`, at
+    # https://github.com/nim-lang/Nim/blob/v2.0.10/lib/system/dollars.nim#L28-L34
+    # can fail to compile. Explicitly choose the non-CTFE overloads which don't
+    # trigger this bug.
+    #
+    # This can be removed once Nim v2.0.10 isn't supported by nim-json-rpc.
+    let nonConstLength = length
+
+    let expected = "Expected " & $nonConstLength & " JSON parameter(s) but got "
+
+    if params.positional.len != length:
+      raise newException(RequestDecodeError,
+        expected & $params.positional.len)
+  else:
+    let expected = "Expected " & $length & " JSON parameter(s) but got "
 
 template setupPositional(setup: static[RpcSetup], params: RequestParamsRx) =
   ## Generate code to check positional params length
@@ -141,11 +154,11 @@ template unpackPositional(params: RequestParamsRx,
   else:
     # mandatory args
     # A and C fall into this category
-    # unpack Nim type and assign from json
+    # unpack Nim type and assign from JSON
     if params.notNull(pos):
       innerNode()
 
-proc makeType(typeName, params: NimNode): NimNode =
+func makeType(typeName, params: NimNode): NimNode =
   ## Generate type section contains an object definition
   ## with fields of handler params
   let typeSec = quote do:
@@ -159,14 +172,14 @@ proc makeType(typeName, params: NimNode): NimNode =
     obj[2] = recList
   typeSec
 
-proc makeParams(retType: NimNode, params: NimNode): seq[NimNode] =
+func makeParams(retType: NimNode, params: NimNode): seq[NimNode] =
   ## Convert rpc params into handler params
   result.add retType
   if params.len > 1:
     for i in 1..<params.len:
       result.add params[i]
 
-proc makeHandler(procName, params, procBody, returnInner: NimNode): NimNode =
+func makeHandler(procName, params, procBody, returnInner: NimNode): NimNode =
   ## Generate rpc handler proc
   let
     returnType = quote do: Future[`returnInner`]
@@ -180,15 +193,15 @@ proc makeHandler(procName, params, procBody, returnInner: NimNode): NimNode =
     pragmas = pragmas
   )
 
-proc ofStmt(x, paramsObj, paramName, paramType: NimNode): NimNode =
+func ofStmt(x, paramsObj, paramName, paramType: NimNode): NimNode =
   let caseStr = $paramName
   result = nnkOfBranch.newTree(
     quote do: `caseStr`,
     quote do:
       `paramsObj`.`paramName` = unpackArg(`x`.value, `caseStr`, `paramType`)
   )
 
-proc setupNamed(paramsObj, paramsIdent, params: NimNode): NimNode =
+func setupNamed(paramsObj, paramsIdent, params: NimNode): NimNode =
   let x = ident"x"
 
   var caseStmt = nnkCaseStmt.newTree(
@@ -206,7 +219,7 @@ proc setupNamed(paramsObj, paramsIdent, params: NimNode): NimNode =
     for `x` in `paramsIdent`.named:
       `caseStmt`
 
-proc wrapServerHandler*(methName: string, params, procBody, procWrapper: NimNode): NimNode =
+func wrapServerHandler*(methName: string, params, procBody, procWrapper: NimNode): NimNode =
   ## This proc generate something like this:
   ##
   ## proc rpcHandler(paramA: ParamAType, paramB: ParamBType): Future[ReturnType] =