fix: use robocopy in copy_file#is_directory and copy_to_directory (#26)

so we don't hit the file path length limit of xcopy

lib/private/copy_file.bzl

@@ -50,23 +50,24 @@ def copy_cmd(ctx, src, dst):
 
     # Flags are documented at
     # https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/copy
-    # https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/xcopy
+    # https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/robocopy
+    # NB: robocopy return non-zero exit codes on success so we must exit 0 after calling it
     if dst.is_directory:
-        cmd_tmpl = "@xcopy \"%s\" \"%s\\\" /V /E /H /Y /Q >NUL"
+        cmd_tmpl = "@robocopy \"{src}\" \"{dst}\" /E >NUL & @exit 0"
         mnemonic = "CopyDirectory"
-        progress_message = "Copying directory"
+        progress_message = "Copying directory %s" % src.path
     else:
-        cmd_tmpl = "@copy /Y \"%s\" \"%s\" >NUL"
+        cmd_tmpl = "@copy /Y \"{src}\" \"{dst}\" >NUL"
         mnemonic = "CopyFile"
-        progress_message = "Copying file"
+        progress_message = "Copying file %s" % src.path
 
     ctx.actions.write(
         output = bat,
         # Do not use lib/shell.bzl's shell.quote() method, because that uses
         # Bash quoting syntax, which is different from cmd.exe's syntax.
-        content = cmd_tmpl % (
-            src.path.replace("/", "\\"),
-            dst.path.replace("/", "\\"),
+        content = cmd_tmpl.format(
+            src = src.path.replace("/", "\\"),
+            dst = dst.path.replace("/", "\\"),
         ),
         is_executable = True,
     )

lib/private/copy_to_directory.bzl

@@ -197,7 +197,7 @@ mkdir "%s" >NUL 2>NUL
 
         # copy & xcopy flags are documented at
         # https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/copy
-        # https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/xcopy
+        # https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/robocopy
         cmds.append("""
 if not exist "{src}" (
     echo file "{src}" does not exist
@@ -205,7 +205,7 @@ if not exist "{src}" (
 )
 if exist "{src}\\*" (
     mkdir "{dst}" >NUL 2>NUL
-    xcopy "{src}\\*" "{dst}" /V /E /H /Y /Q >NUL
+    robocopy "{src}" "{dst}" /E >NUL
 ) else (
     mkdir "{dst_dir}" >NUL 2>NUL
     copy /Y "{src}" "{dst}" >NUL
@@ -216,6 +216,9 @@ if exist "{src}\\*" (
             dst = dst_path.replace("/", "\\"),
         ))
 
+    # robocopy return non-zero exit codes on success so we must exit 0 when we are done
+    cmds.append("exit 0")
+
     ctx.actions.write(
         output = bat,
         # Do not use lib/shell.bzl's shell.quote() method, because that uses