Macro helper for wrapping a C macro that declares a new C variable.

It handles emitting the appropriate C code for calling the macro. Additionally it defines a new Nim variable using importc which imports the declared variable.

Example:

import macros
import cdecl 

{.emit: """/*TYPESECTION*/
    /* define example C Macro for testing */
    #define C_DEFINE_VAR(NM, SZ) int NM[SZ]
    #define C_DEFINE_VAR_DUO(NM, SZ, NM2) int NM[SZ]
    """.}

proc CDefineVar*(name: CToken, size: static[int]): array[size, int] {.
  cdeclmacro: "C_DEFINE_VAR".}

# Then it's possible to invoke CDefineVar to call the C macro and
# generate a variable:
const cVarSz = 4
CDefineVar(myVar, cVarSz)

static:
  discard """`CDefineVar` generates code that looks like:"""
  discard quote do:
    template CDefineVar*(name: untyped, size: static[int]) =
      var name* {.inject, importc, nodecl.}: array[size, int]
    {.emit: "/*VARSECTION*/\nC_DEFINE_VAR($1, $2); " % [ symbolName(name), $size, ] .}