feat(os): expandTilde supports "~bob". closes nim-lang#24655

lib/pure/os.nim

@@ -127,14 +127,38 @@ proc expandTilde*(path: string): string {.
     assert expandTilde("~/foo/bar") == getHomeDir() / "foo/bar"
     assert expandTilde("/foo/bar") == "/foo/bar"
 
+  template tryGetHomeOrRet =
+    result = getHomeDir()
+    if result == "":
+      result = path
+      return
+
   if len(path) == 0 or path[0] != '~':
     result = path
   elif len(path) == 1:
-    result = getHomeDir()
+    tryGetHomeOrRet
   elif (path[1] in {DirSep, AltSep}):
-    result = getHomeDir() / path.substr(2)
+    tryGetHomeOrRet
+    result = result / path.substr(2)
+  elif compiles(getHomeDir("bob")):
+    # handle path beginning with `~bob` and `~bob/`
+    # which means home of bob
+    var i = path.find(DirSep, 1)
+    if i < 0:
+      i = len(path)
+
+    let
+      name = path[1..<i]
+      userhome = getHomeDir(name)
+
+    if userhome == "" and hostOS == "vsworks":
+      # XXX: As of the moment this line is written,
+      #  hostOS won't be "vsworks" yet.
+      return path
+
+    result = userhome & path.substr(i)
+
   else:
-    # TODO: handle `~bob` and `~bob/` which means home of bob
     result = path
 
 proc quoteShellWindows*(s: string): string {.noSideEffect, rtl, extern: "nosp$1".} =