VM: cannot use generated proc with split declaration / definition

[flyx]

import macros

proc genProcDeclAndDef(name: var NimNode): NimNode {.compileTime.} =
  result = newStmtList()
  name = genSym(nskProc, "myProc")

  # generate proc declaration without implementation and add {.noconv.} pragma
  result.add(newProc(name, [newIdentNode("int")], newEmptyNode()))
  result[0][4] = newTree(nnkPragma, newIdentNode("noconv"))

  # generate proc implementation, remove {.noconv.} pragma
  result.add(copyNimTree(result[0]))
  result[1][4] = newEmptyNode()

  # proc implementation
  result[1][6] = newStmtList(newLit(42))

type MyProcType = proc(): int {.noconv.}

macro setProcVar(varName: MyProcType): typed =
  var procName: NimNode
  result = genProcDeclAndDef(procName)
  result.add(newAssignment(varName, procName))

var myProcVar: MyProcType
setProcVar(myProcVar)

This yields:

test1.nim(26, 11) template/generic instantiation from here                                                                                                                            
test1.nim(5, 16) Error: type mismatch: got (proc (): int) but expected 'MyProcType = proc (): int{.noconv.}'

Apparently, Nim fails to fetch the pragma from the declaration when doing this check. Also interesting what happens if I remove result[1][4] = newEmptyNode() (which deletes the pragma from the definition):

test1.nim(5, 16) Error: internal error: still forwarded: myProc                                                                                                                       
Traceback (most recent call last)                                                                                                                                                     
nim.nim(120)             nim                                                                                                                                                          
nim.nim(76)              handleCmdLine                                                                                                                                                
main.nim(252)            mainCommand                                                                                                                                                  
main.nim(66)             commandCompileToC                                                                                                                                            
cgen.nim(1328)           cgenWriteModules                                                                                                                                             
cgen.nim(1232)           finishModule                                                                                                                                                 
msgs.nim(994)            internalError                                                                                                                                                
msgs.nim(968)            liMessage                                                                                                                                                    
msgs.nim(840)            handleError                                                                                                                                                  
msgs.nim(824)            quit                                                                                                                                                         
FAILURE

It compiles if I do not split declaration and implementation:

  result.add(newProc(name, [newIdentNode("int")], newStmtList(newLit(42))))
  result[0][4] = newTree(nnkPragma, newIdentNode("noconv"))

The problem also vanishes if I do not genSym the proc:

  name = newIdentNode("myProc")