rebase: make the backend configurable via config setting

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/config/rebase.txt b/Documentation/config/rebase.txt
index d98e32d812e76f24f6eca49e32af910b1ddd0967..e6ae30c9999b67d8bbadf03566d768b1bf7c7232 100644 (file)
--- a/Documentation/config/rebase.txt
+++ b/Documentation/config/rebase.txt
@@ -5,6 +5,14 @@ rebase.useBuiltin::
        is always used. Setting this will emit a warning, to alert any
        remaining users that setting this now does nothing.
 
+rebase.backend::
+       Default backend to use for rebasing.  Possible choices are
+       'am' or 'merge' (note that the merge backend is sometimes also
+       refered to as the interactive backend or the interactive
+       machinery elsewhere in the docs).  Also, in the future, if the
+       merge backend gains all remaining capabilities of the am
+       backend, this setting may become unused.
+
 rebase.stat::
        Whether to show a diffstat of what changed upstream since the last
        rebase. False by default.

diff --git a/builtin/rebase.c b/builtin/rebase.c
index ffaa7935240980557bc589d555beec30a006769d..f0a862f41b5c4c3500a7282219fdc6ae7f2bf1b7 100644 (file)
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -60,6 +60,7 @@ enum empty_type {
 struct rebase_options {
        enum rebase_type type;
        enum empty_type empty;
+       const char *default_backend;
        const char *state_dir;
        struct commit *upstream;
        const char *upstream_name;
@@ -100,6 +101,7 @@ struct rebase_options {
 #define REBASE_OPTIONS_INIT {                          \
                .type = REBASE_UNSPECIFIED,             \
                .empty = EMPTY_UNSPECIFIED,             \
+               .default_backend = "am",                \
                .flags = REBASE_NO_QUIET,               \
                .git_am_opts = ARGV_ARRAY_INIT,         \
                .git_format_patch_opt = STRBUF_INIT     \
@@ -1272,6 +1274,10 @@ static int rebase_config(const char *var, const char *value, void *data)
                return 0;
        }
 
+       if (!strcmp(var, "rebase.backend")) {
+               return git_config_string(&opts->default_backend, var, value);
+       }
+
        return git_default_config(var, value, data);
 }
 
@@ -1900,9 +1906,23 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
                        if (strcmp(options.git_am_opts.argv[i], "-q"))
                                break;
 
-               if (is_interactive(&options) && i >= 0)
-                       die(_("cannot combine am options with either "
-                             "interactive or merge options"));
+               if (i >= 0) {
+                       if (is_interactive(&options))
+                               die(_("cannot combine am options with either "
+                                     "interactive or merge options"));
+                       else
+                               options.type = REBASE_AM;
+               }
+       }
+
+       if (options.type == REBASE_UNSPECIFIED) {
+               if (!strcmp(options.default_backend, "merge"))
+                       options.type = REBASE_MERGE;
+               else if (!strcmp(options.default_backend, "am"))
+                       options.type = REBASE_AM;
+               else
+                       die(_("Unknown rebase backend: %s"),
+                           options.default_backend);
        }
 
        switch (options.type) {
@@ -1915,10 +1935,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
                options.state_dir = apply_dir();
                break;
        default:
-               /* the default rebase backend is `--am` */
-               options.type = REBASE_AM;
-               options.state_dir = apply_dir();
-               break;
+               BUG("options.type was just set above; should be unreachable.");
        }
 
        if (options.empty == EMPTY_UNSPECIFIED) {