src/Pure/Admin/component_polyml.scala

           setup = MinGW.env_prefix,
           libs = Set("libgcc_s_seh", "libgmp", "libstdc++", "libwinpthread"))
       }
       else error("Bad platform: " + quote(platform.toString))
 
-    def standard_path(path: Path): String = mingw.standard_path(path)
+    def standard_path(path: Path): String =
+      mingw.standard_path(File.standard_path(path))
 
     def polyml(arch_64: Boolean): String =
       (if (arch_64) platform.arch_64 else platform.arch_64_32) + "-" + platform.os_name
 
     def sha1: String = platform.arch_64 + "-" + platform.os_name

 
     /* configure and make */
 
     val configure_options = {
       val options1 =
-        if (gmp_root.nonEmpty || platform.is_windows) List("--with-gmp")
-        else List("--without-gmp")
+        if (gmp_root.nonEmpty) List("--with-gmp") else List("--without-gmp")
 
       def detect_CFLAGS(s: String): Boolean = s.startsWith("CFLAGS=")
 
       val info_options =
         if (info.options.exists(detect_CFLAGS)) info.options

 
 
 
   /** skeleton for component **/
 
-  def default_gmp_url: String =
-    if (Platform.is_windows) ""
-    else "https://gmplib.org/download/gmp/gmp-6.3.0.tar.bz2"
+  val default_gmp_url = "https://gmplib.org/download/gmp/gmp-6.3.0.tar.bz2"
 
   val default_polyml_url = "https://github.com/polyml/polyml/archive"
   val default_polyml_version = "90c0dbb2514e"
   val default_polyml_name = "polyml-5.9.1"
 

     Isabelle_System.with_tmp_dir("build") { build_dir =>
       /* GMP library */
 
       val gmp_root1: Option[Path] =
         if (gmp_url.isEmpty) gmp_root
-        else if (platform.is_windows) error("Bad GMP source for Windows: use MinGW version instead")
         else {
           val gmp_dir = Isabelle_System.make_directory(build_dir + Path.basic("gmp"))
 
           val archive_name =
             Url.get_base_name(gmp_url).getOrElse(error("No base name in " + quote(gmp_url)))