Error: internal error: expr: var not init sevColor_994035

[copygirl]

The following code produces the compiler error:

util/log.nim(24, 24) Error: internal error: expr: var not init sevColor_994035

import
  macros,
  strutils,
  terminal

type LogSeverity* = enum
  sevError = "Error"
  sevWarn  = "Warn"
  sevInfo  = "Info"
  sevDebug = "Debug"

macro log*(severity: static[LogSeverity], group: static[string], m: varargs[typed]): untyped =
  let sevStr   = align("[" & toUpperAscii($severity) & "] ", 8)
  let sevColor = case severity
    of sevError: fgRed
    of sevWarn:  fgYellow
    of sevInfo:  fgWhite
    of sevDebug: fgBlack
  
  let groupStr = "[" & $group & "] "
  
  result = quote do:
    setStyle({ styleBright })
    setForegroundColor(sevColor) # <==
    write(stdout, sevStr)
    
    setStyle({ styleDim })
    setForegroundColor(fgWhite)
    write(stdout, groupStr)
  
  let wl = newCall(bindSym"styledWriteLine", bindSym"stdout")
  for arg in m: wl.add(arg)
  result.add(wl)

[copygirl]

I suppose it's just lacking a proper error message and I didn't understand the power of quote correctly. If I write the following, it compiles fine:

  result = quote do:
    setStyle({ styleBright })
    setForegroundColor(ForegroundColor(`sevColor`))
    write(stdout, `sevStr`)
    
    setStyle({ styleDim })
    setForegroundColor(fgWhite)
    write(stdout, `groupStr`)

[LemonBoy]

See #8574

[copygirl]

Though, I wonder... Wouldn't it be nice if this was how quote worked in the first place? Or is there a reason why we have to use the backticks?

[mratsim]

Yes, to show intentional interpolation. The compile-time scope shouldn't leak into the run-time scope.
For example, the result variable of the macro shouldn't leak in the result variable of a proc you are building like #7791.