Can't deepCopy inside macros

[def-]

import macros

macro m(x: expr): stmt =
  var y: NimNode
  y.deepCopy(x)

m(10)

I see there is a copyNimNode and copyNimTree, but this should at least throw another error than this:

x.nim(5, 3) Error: internal error: cannot generate code for: mDeepCopy
Traceback (most recent call last)
nim.nim(94)              nim
nim.nim(56)              handleCmdLine
main.nim(251)            mainCommand
main.nim(62)             commandCompileToC
modules.nim(203)         compileProject
modules.nim(151)         compileModule
passes.nim(197)          processModule
passes.nim(137)          processTopLevelStmt
sem.nim(446)             myProcess
sem.nim(420)             semStmtAndGenerateGenerics
semstmts.nim(1343)       semStmt
semexprs.nim(893)        semExprNoType
semexprs.nim(2086)       semExpr
semexprs.nim(877)        semDirectOp
semexprs.nim(860)        afterCallActions
sem.nim(354)             semMacroExpr
vm.nim(1478)             evalMacroCall
vmgen.nim(1776)          genProc
vmgen.nim(239)           gen
vmgen.nim(1613)          gen
vmgen.nim(239)           gen
vmgen.nim(1613)          gen
vmgen.nim(239)           gen
vmgen.nim(1573)          gen
vmgen.nim(1028)          genMagic
msgs.nim(849)            internalError
msgs.nim(826)            liMessage
msgs.nim(728)            handleError
FAILURE

[genotrance]

No longer crashes with #head.

-------- SNIPPET --------
import macros

macro m(x: expr): stmt =
  var y: NimNode
  y.deepCopy(x)

m(10)
-------------------------

-------- OUTPUT --------
Hint: used config file 'c:\Users\gt\Desktop\dl\programming\nimdevel\config\nim.cfg' [Conf]
Hint: system [Processing]
Hint: temp [Processing]
Hint: macros [Processing]
temp.nim(3, 12) Warning: expr is deprecated [Deprecated]
temp.nim(3, 19) Warning: stmt is deprecated [Deprecated]
temp.nim(7, 2) template/generic instantiation from here
temp.nim(5, 4) Error: cannot generate code for: mDeepCopy
------------------------

-------- NIMTEMP --------
Hint: used config file 'c:\Users\gt\Desktop\dl\programming\nimdevel\config\nim.cfg' [Conf]
Hint: system [Processing]
Hint: temp [Processing]
Hint: macros [Processing]
temp.nim(3, 12) Warning: expr is deprecated [Deprecated]
temp.nim(3, 19) Warning: stmt is deprecated [Deprecated]
temp.nim(7, 2) template/generic instantiation from here
temp.nim(5, 4) Error: cannot generate code for: mDeepCopy
Traceback (most recent call last)
nim.nim(121)             nim
nim.nim(77)              handleCmdLine
main.nim(173)            mainCommand
main.nim(77)             commandCompileToC
modules.nim(242)         compileProject
modules.nim(182)         compileModule
passes.nim(250)          processModule
passes.nim(139)          processTopLevelStmt
sem.nim(576)             myProcess
sem.nim(544)             semStmtAndGenerateGenerics
semstmts.nim(1975)       semStmt
semexprs.nim(797)        semExprNoType
semexprs.nim(2285)       semExpr
semexprs.nim(781)        semDirectOp
semexprs.nim(677)        afterCallActions
sem.nim(441)             semMacroExpr
vm.nim(1752)             evalMacroCall
vmgen.nim(2033)          genProc
vmgen.nim(258)           gen
vmgen.nim(1843)          gen
vmgen.nim(258)           gen
vmgen.nim(1793)          gen
vmgen.nim(1180)          genMagic
msgs.nim(1049)           globalError
msgs.nim(1037)           liMessage
msgs.nim(891)            handleError
msgs.nim(876)            quit
-------------------------

-------- VERSION --------
Nim Compiler Version 0.18.1 [Windows: i386]
Copyright (c) 2006-2018 by Andreas Rumpf

git hash: 9d4fd1f1bbc0d8a2327699dd07283260d85a5245
active boot switches: -d:release
-------------------------