findExe finds cmd and bat files; refs #5049

lib/pure/ospaths.nim

@@ -562,24 +562,33 @@ when declared(getEnv) or defined(nimscript):
       if lstat(path, rawInfo) < 0'i32: result = false
       else: result = S_ISLNK(rawInfo.st_mode)
 
-  proc findExe*(exe: string, followSymlinks: bool = true): string {.
+  const
+    ExeExts* = when defined(windows): ["exe", "cmd", "bat"] else: [""] ## \
+      ## platform specific file extension for executables. On Windows
+      ## ``["exe", "cmd", "bat"]``, on Posix ``[""]``.
+
+  proc findExe*(exe: string, followSymlinks: bool = true;
+                extensions=ExeExts): string {.
     tags: [ReadDirEffect, ReadEnvEffect, ReadIOEffect].} =
     ## Searches for `exe` in the current working directory and then
     ## in directories listed in the ``PATH`` environment variable.
-    ## Returns "" if the `exe` cannot be found. On DOS-like platforms, `exe`
+    ## Returns "" if the `exe` cannot be found. `exe`
-    ## is added the `ExeExt <#ExeExt>`_ file extension if it has none.
+    ## is added the `ExeExts <#ExeExts>`_ file extensions if it has none.
     ## If the system supports symlinks it also resolves them until it
     ## meets the actual file. This behavior can be disabled if desired.
-    result = addFileExt(exe, ExeExt)
+    for ext in extensions:
+      result = addFileExt(exe, ext)
       if existsFile(result): return
     var path = string(getEnv("PATH"))
     for candidate in split(path, PathSep):
       when defined(windows):
         var x = (if candidate[0] == '"' and candidate[^1] == '"':
                   substr(candidate, 1, candidate.len-2) else: candidate) /
-               result
+               exe
       else:
-        var x = expandTilde(candidate) / result
+        var x = expandTilde(candidate) / exe
+      for ext in extensions:
+        let x = addFileExt(x, ext)
         if existsFile(x):
           when not defined(windows) and declared(os):
             while followSymlinks: # doubles as if here