Big compiler Cleanup (#14777)

compiler/commands.nim

@@ -53,11 +53,10 @@ const
       "Copyright (c) 2006-" & copyrightYear & " by Andreas Rumpf\n"
 
 proc genFeatureDesc[T: enum](t: typedesc[T]): string {.compileTime.} =
-  var x = ""
-  for f in low(T)..high(T):
-    if x.len > 0: x.add "|"
-    x.add $f
-  x
+  result = ""
+  for f in T:
+    if result.len > 0: result.add "|"
+    result.add $f
 
 const
   Usage = slurp"../doc/basicopt.txt".replace(" //", " ")
@@ -146,24 +145,24 @@ proc splitSwitch(conf: ConfigRef; switch: string, cmd, arg: var string, pass: TC
 proc processOnOffSwitch(conf: ConfigRef; op: TOptions, arg: string, pass: TCmdLinePass,
                         info: TLineInfo) =
   case arg.normalize
-  of "","on": conf.options = conf.options + op
-  of "off": conf.options = conf.options - op
+  of "","on": conf.options.incl op
+  of "off": conf.options.excl op
   else: localError(conf, info, errOnOrOffExpectedButXFound % arg)
 
 proc processOnOffSwitchOrList(conf: ConfigRef; op: TOptions, arg: string, pass: TCmdLinePass,
                               info: TLineInfo): bool =
   result = false
   case arg.normalize
-  of "on": conf.options = conf.options + op
-  of "off": conf.options = conf.options - op
+  of "on": conf.options.incl op
+  of "off": conf.options.excl op
   of "list": result = true
   else: localError(conf, info, errOnOffOrListExpectedButXFound % arg)
 
 proc processOnOffSwitchG(conf: ConfigRef; op: TGlobalOptions, arg: string, pass: TCmdLinePass,
                          info: TLineInfo) =
   case arg.normalize
-  of "", "on": conf.globalOptions = conf.globalOptions + op
-  of "off": conf.globalOptions = conf.globalOptions - op
+  of "", "on": conf.globalOptions.incl op
+  of "off": conf.globalOptions.excl op
   else: localError(conf, info, errOnOrOffExpectedButXFound % arg)
 
 proc expectArg(conf: ConfigRef; switch, arg: string, pass: TCmdLinePass, info: TLineInfo) =