Path substitution for --out and --outdir (#12796)

* Enable pathSubs for --out and --outDir
* Cleanup

compiler/commands.nim

@@ -392,15 +392,15 @@ proc processSwitch*(switch, arg: string, pass: TCmdLinePass, info: TLineInfo;
     conf.lazyPaths.keepItIf(it != path)
   of "nimcache":
     expectArg(conf, switch, arg, pass, info)
-    conf.nimcacheDir = processPath(conf, arg, info, true)
+    conf.nimcacheDir = processPath(conf, arg, info, notRelativeToProj=true)
   of "out", "o":
     expectArg(conf, switch, arg, pass, info)
-    let f = splitFile(arg.expandTilde)
+    let f = splitFile(processPath(conf, arg, info, notRelativeToProj=true).string)
     conf.outFile = RelativeFile f.name & f.ext
     conf.outDir = toAbsoluteDir f.dir
   of "outdir":
     expectArg(conf, switch, arg, pass, info)
-    conf.outDir = toAbsoluteDir arg.expandTilde
+    conf.outDir = processPath(conf, arg, info, notRelativeToProj=true)
   of "docseesrcurl":
     expectArg(conf, switch, arg, pass, info)
     conf.docSeeSrcUrl = arg

compiler/options.nim

@@ -586,9 +586,7 @@ proc pathSubs*(conf: ConfigRef; p, config: string): string =
     "projectname", conf.projectName,
     "projectpath", conf.projectPath.string,
     "projectdir", conf.projectPath.string,
-    "nimcache", getNimcacheDir(conf).string])
-  if "~/" in result:
-    result = result.replace("~/", home & '/')
+    "nimcache", getNimcacheDir(conf).string]).expandTilde
 
 iterator nimbleSubs*(conf: ConfigRef; p: string): string =
   let pl = p.toLowerAscii