bin/braid in braid-1.0.20 vs bin/braid in braid-1.0.21

@@ -18,10 +18,23 @@
 
     All operations will be executed in the braid/track branch.
     You can then merge back or cherry-pick changes.
   TXT
 
+  # Duplicated from Braid::Command.run. :(
+  def die(msg)
+    puts "Braid: Error: #{msg}"
+    exit(1)
+  end
+
+  # The "main" library doesn't provide a way to do this??
+  def check_no_extra_args!
+    if @argv.length > 0
+      die 'Extra argument(s) passed to command.'
+    end
+  end
+
   mode(:add) {
     description <<-TXT
       Add a new mirror to be tracked.
 
         * adds metadata about the mirror to .braids.json
@@ -41,10 +54,11 @@
     TXT
 
     mixin :argument_url, :optional_local_path, :option_branch, :option_tag, :option_revision, :option_verbose, :option_path
 
     run {
+      check_no_extra_args!
       Braid.verbose = verbose
       Braid::Command.run(:add, url, {'path' => local_path, 'branch' => branch, 'tag' => tag, 'revision' => revision, 'remote_path' => path})
     }
   }
 
@@ -66,10 +80,11 @@
     TXT
 
     mixin :optional_local_path, :option_head, :option_revision, :option_tag, :option_branch, :option_verbose, :option_keep_remote
 
     run {
+      check_no_extra_args!
       options = {
         'branch' => branch,
         'tag' => tag,
         'revision' => revision,
         'head' => head,
@@ -94,10 +109,11 @@
     TXT
 
     mixin :argument_local_path, :option_verbose, :option_keep_remote
 
     run {
+      check_no_extra_args!
       options = {
         :keep => keep
       }
       Braid.verbose = verbose
       Braid::Command.run(:remove, local_path, options)
@@ -105,17 +121,28 @@
   }
 
   mode(:diff) {
     description <<-TXT
       Show diff of local changes to mirror.
+
+      Additional arguments for "git diff" may be passed.  "--" should be used to
+      ensure they are not parsed as Braid options.  File paths to limit the diff are
+      relative to the downstream repository (for more convenient completion), even
+      though file paths in the diff are relative to the mirror.
     TXT
 
     mixin :optional_local_path, :option_verbose, :option_keep_remote
 
+    synopsis (Main::Usage.default_synopsis(self) + ' [-- git_diff_arg*]')
+
     run {
+      if @argv.length > 0 && @argv[0] == '--'
+        @argv.shift
+      end
       options = {
-        'keep' => keep
+        'keep' => keep,
+        'git_diff_args' => @argv
       }
       Braid.verbose = verbose
       Braid::Command.run(:diff, local_path, options)
     }
   }
@@ -126,10 +153,11 @@
     TXT
 
     mixin :argument_local_path, :option_branch, :option_verbose, :option_keep_remote
 
     run {
+      check_no_extra_args!
       options = {
         'keep' => keep,
         'branch' => branch
       }
       Braid.verbose = verbose
@@ -143,29 +171,32 @@
     TXT
 
     mixin :optional_local_path, :option_verbose, :option_force
 
     run {
+      check_no_extra_args!
       Braid.verbose = verbose
       Braid.force = force
       Braid::Command.run(:setup, local_path)
     }
   }
 
   mode(:version) {
     description 'Show braid version.'
 
     run {
+      check_no_extra_args!
       puts "braid #{Braid::VERSION}"
     }
   }
 
   mode(:status) {
     description 'Show the status of all tracked mirrors (and if updates are available).'
 
     mixin :optional_local_path, :option_verbose
 
     run {
+      check_no_extra_args!
       Braid.verbose = verbose
       Braid::Command.run(:status, local_path)
     }
   }