Async function causes internal error during compilation.

[FasterSpeeding]

Async function causes Error: internal error: genTypeInfo(tyNil) during compilation to C.

Example

import asyncdispatch
import json

type
    NilType = type(nil)

    Unspecified = ref object

var
    unspecified: Unspecified = Unspecified()

proc `%`(opt: NilType): typeof json.newJNull() =
    return json.newJNull() 

proc modifyChannel*(
        channelID: string,
        name: string | NilType | Unspecified = unspecified,
    ): Future[json.JsonNode] {.async.} =
    var node: json.JsonNode = %*{"id": channelID}
    if name != unspecified:
        node.add("name", %name)
    return node

echo waitFor modifyChannel("9292929", name=nil)
echo waitFor modifyChannel("9292929")

Current Output

Error: internal error: genTypeInfo(tyNil)
No stack traceback available
To create a stacktrace, rerun compilation with ./koch temp c <file>

With the traceback being

Error: internal error: genTypeInfo(tyNil)
Traceback (most recent call last)
C:\Users\Lukec\Documents\VSC\Nim\compiler\nim.nim(118) nim
C:\Users\Lukec\Documents\VSC\Nim\compiler\nim.nim(95) handleCmdLine
C:\Users\Lukec\Documents\VSC\Nim\compiler\cmdlinehelper.nim(105) loadConfigsAndRunMainCommand
C:\Users\Lukec\Documents\VSC\Nim\compiler\main.nim(190) mainCommand
C:\Users\Lukec\Documents\VSC\Nim\compiler\main.nim(92) commandCompileToC
C:\Users\Lukec\Documents\VSC\Nim\compiler\modules.nim(143) compileProject
C:\Users\Lukec\Documents\VSC\Nim\compiler\modules.nim(84) compileModule
C:\Users\Lukec\Documents\VSC\Nim\compiler\passes.nim(210) processModule
C:\Users\Lukec\Documents\VSC\Nim\compiler\passes.nim(86) processTopLevelStmt
C:\Users\Lukec\Documents\VSC\Nim\compiler\cgen.nim(1891) myProcess
C:\Users\Lukec\Documents\VSC\Nim\compiler\cgen.nim(974) genProcBody
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgstmts.nim(1417) genStmts
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(2610) expr
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(2272) genMagicExpr
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(1055) genEcho
C:\Users\Lukec\Documents\VSC\Nim\compiler\cgen.nim(602) initLocExpr
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(2630) expr
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(2409) genArrayConstr
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(2618) expr
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgcalls.nim(568) genCall
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgcalls.nim(194) genPrefixCall
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgcalls.nim(177) genArg
C:\Users\Lukec\Documents\VSC\Nim\compiler\cgen.nim(615) initLocExprSingleUse
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(2618) expr
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgcalls.nim(568) genCall
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgcalls.nim(194) genPrefixCall
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgcalls.nim(177) genArg
C:\Users\Lukec\Documents\VSC\Nim\compiler\cgen.nim(615) initLocExprSingleUse
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(2618) expr
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgcalls.nim(568) genCall
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgcalls.nim(207) genPrefixCall
C:\Users\Lukec\Documents\VSC\Nim\compiler\cgen.nim(602) initLocExpr
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(2548) expr
C:\Users\Lukec\Documents\VSC\Nim\compiler\cgen.nim(1199) genProc
C:\Users\Lukec\Documents\VSC\Nim\compiler\cgen.nim(1164) genProcNoForward
C:\Users\Lukec\Documents\VSC\Nim\compiler\cgen.nim(1030) genProcAux
C:\Users\Lukec\Documents\VSC\Nim\compiler\cgen.nim(974) genProcBody
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgstmts.nim(1417) genStmts
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(2648) expr
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(2433) genStmtList
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgstmts.nim(1417) genStmts
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(2648) expr
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(2433) genStmtList
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgstmts.nim(1417) genStmts
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(2610) expr
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(2182) genMagicExpr
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(1263) genNew
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgexprs.nim(1220) rawGenNew
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgtypes.nim(1378) genTypeInfo
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgtypes.nim(1040) genTypeInfoAux
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgtypes.nim(1387) genTypeInfo
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgtypes.nim(1149) genObjectInfo
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgtypes.nim(1081) genObjectFields
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgtypes.nim(1136) genObjectFields
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgtypes.nim(1343) genTypeInfo
C:\Users\Lukec\Documents\VSC\Nim\compiler\ccgtypes.nim(1394) genTypeInfo
C:\Users\Lukec\Documents\VSC\Nim\compiler\msgs.nim(565) internalError
C:\Users\Lukec\Documents\VSC\Nim\compiler\msgs.nim(443) rawMessage
C:\Users\Lukec\Documents\VSC\Nim\compiler\msgs.nim(440) rawMessage
C:\Users\Lukec\Documents\VSC\Nim\compiler\msgs.nim(356) handleError
C:\Users\Lukec\Documents\VSC\Nim\compiler\msgs.nim(346) quit
FAILURE

Expected Output

{"id":"9292929","name":null}
{"id":"9292929"}

Possible Solution

• This code seems to compile and run as expected when modifyChannel isn't async (and isn't being waited for or returning a Future).

Additional Information

• This is also an issue on the stable release 1.0.6 (git hash: 89b39ee8fe271d0e1b75c15a4c6cf82eb9c13aea)
• This issue is blocking my project Tuxedo (a pet project discord api wrapper).

  
  Nim Compiler Version 1.1.1 [Windows: amd64]
  Compiled at 2020-02-07
  Copyright (c) 2006-2019 by Andreas Rumpf

git hash: 79ec8c257183e01c01811a34e3930de7814756fb

[shirleyquirk]

Using TinyRtti (calls genTypeInfoV2 instead) this compiles and runs, i.e. --gc:arc --gc:destructors --gc:orc all work