rebase: factor out command line option processing

diff --git a/builtin/read-tree.c b/builtin/read-tree.c
index 8bdcab11389e8b4facab355f27f0e1926134b86f..73c89ed15ba2fb0c470141499c3390b77cf1d81c 100644 (file)
--- a/builtin/read-tree.c
+++ b/builtin/read-tree.c
@@ -16,6 +16,7 @@
 #include "resolve-undo.h"
 
 static int nr_trees;
+static int read_empty;
 static struct tree *trees[MAX_UNPACK_TREES];
 
 static int list_tree(unsigned char *sha1)
@@ -32,7 +33,7 @@ static int list_tree(unsigned char *sha1)
 }
 
 static const char * const read_tree_usage[] = {
-       "git read-tree [[-m [--trivial] [--aggressive] | --reset | --prefix=<prefix>] [-u [--exclude-per-directory=<gitignore>] | -i]] [--no-sparse-checkout] [--index-output=<file>] <tree-ish1> [<tree-ish2> [<tree-ish3>]]",
+       "git read-tree [[-m [--trivial] [--aggressive] | --reset | --prefix=<prefix>] [-u [--exclude-per-directory=<gitignore>] | -i]] [--no-sparse-checkout] [--index-output=<file>] (--empty | <tree-ish1> [<tree-ish2> [<tree-ish3>]])",
        NULL
 };
 
@@ -106,7 +107,9 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
                { OPTION_CALLBACK, 0, "index-output", NULL, "FILE",
                  "write resulting index to <FILE>",
                  PARSE_OPT_NONEG, index_output_cb },
-               OPT__VERBOSE(&opts.verbose_update),
+               OPT_SET_INT(0, "empty", &read_empty,
+                           "only empty the index", 1),
+               OPT__VERBOSE(&opts.verbose_update, "be verbose"),
                OPT_GROUP("Merging"),
                OPT_SET_INT('m', NULL, &opts.merge,
                            "perform a merge in addition to a read", 1),
@@ -166,6 +169,11 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
                        die("failed to unpack tree object %s", arg);
                stage++;
        }
+       if (nr_trees == 0 && !read_empty)
+               warning("read-tree: emptying the index with no arguments is deprecated; use --empty");
+       else if (nr_trees > 0 && read_empty)
+               die("passing trees as arguments contradicts --empty");
+
        if (1 < opts.index_only + opts.update)
                die("-u and -i at the same time makes no sense");
        if ((opts.update||opts.index_only) && !opts.merge)
@@ -219,14 +227,9 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
         * "-m ent" or "--reset ent" form), we can obtain a fully
         * valid cache-tree because the index must match exactly
         * what came from the tree.
-        *
-        * The same holds true if we are switching between two trees
-        * using read-tree -m A B.  The index must match B after that.
         */
        if (nr_trees == 1 && !opts.prefix)
                prime_cache_tree(&active_cache_tree, trees[0]);
-       else if (nr_trees == 2 && opts.merge)
-               prime_cache_tree(&active_cache_tree, trees[1]);
 
        if (write_cache(newfd, active_cache, active_nr) ||
            commit_locked_index(&lock_file))