Re: [RFC/PATCH] add: warn when -u or -A is used without filepattern

@@ -107,9 +107,10 @@ apply to the index. See EDITING PATCHES below.
 	from the index if the corresponding files in the working tree
 	have been removed.
 +
-If no <filepattern> is given, default to "."; in other words,
-update all tracked files in the current directory and its
-subdirectories.
+If no <filepattern> is given, the current version of Git defaults to
+"."; in other words, update all tracked files in the current directory
+and its subdirectories. This default will change in a future version
+of Git, hence the form without <filepattern> should not be used.
 
 -A::
 --all::

@@ -363,6 +363,33 @@ static int add_files(struct dir_struct *dir, int flags)
 	return exit_status;
 }
 
+static void warn_pathless_add(const char *option_name) {
+	/*
+	 * To be consistant with "git add -p" and most Git
+	 * commands, we should default to being tree-wide, but
+	 * this is not the original behavior and can't be
+	 * changed until users trained themselves not to type
+	 * "git add -u" or "git add -A". For now, we warn and
+	 * keep the old behavior. Later, this warning can be
+	 * turned into a die(...), and eventually we may
+	 * reallow the command with a new behavior.
+	 */
+	warning(_("The behavior of 'git add %s' with no path argument from a subdirectory of the\n"
+		  "tree will change in Git 2.0 and shouldn't be used anymore.\n"
+		  "To add content for the whole tree, run:\n"
+		  "\n"
+		  "  git add %s :/\n"
+		  "\n"
+		  "To restrict the command to the current directory, run:\n"
+		  "\n"
+		  "  git add %s .\n"
+		  "\n"
+		  "With the current Git version, the command is restricted to the current directory."),
+		option_name,
+		option_name,
+		option_name);
+}
+
 int cmd_add(int argc, const char **argv, const char *prefix)
 {
 	int exit_status = 0;

@@ -373,6 +400,7 @@ int cmd_add(int argc, const char **argv, const char *prefix)
 	int add_new_files;
 	int require_pathspec;
 	char *seen = NULL;
+	const char *option_with_implicit_dot = NULL;
 
 	git_config(add_config, NULL);
 

@@ -392,8 +420,14 @@ int cmd_add(int argc, const char **argv, const char *prefix)
 		die(_("-A and -u are mutually incompatible"));
 	if (!show_only && ignore_missing)
 		die(_("Option --ignore-missing can only be used together with --dry-run"));
-	if ((addremove || take_worktree_changes) && !argc) {
+	if (addremove)
+		option_with_implicit_dot = "--all";
+	if (take_worktree_changes)
+		option_with_implicit_dot = "--update";
+	if (option_with_implicit_dot && !argc) {
 		static const char *here[2] = { ".", NULL };
+		if (prefix)
+			warn_pathless_add(option_with_implicit_dot);
 		argc = 1;
 		argv = here;
 	}