On Sat, Feb 16, 2008 at 05:08:22PM -0800, Junio C Hamano wrote:
> and you say "git checkout next", then after we switch the branch
> we check the upstream (in this case, refs/remotes/linus/next)
> and our branch, and:
>
> (1) if they match, nothing happens;
>
> (2) if you are ahead (i.e. the upstream is a strict ancestor
> of you), one line message tells you so;
>
> (3) otherwise, you are either behind or you and the upstream
> have forked. One line message will tell you which and
> then you will see a "log --pretty=oneline --left-right".
Overall I think this is a sensible idea. For (3), it probably makes
sense to limit the output in some cases. If I checkout a topic branch
that I haven't looked at in a few days or even weeks, I am going to get
spammed with hundreds of commits.
Most of the time what I really want to know is "I am not up to date and
should merge or rebase." Automatically showing _which_ commits diverge
is a convenience that makes sense if there are a handful of them. For
larger cases, the user can easily run "git log upstream...branch".
Of course this is speculation and gut feeling; I'll try running with
this for a few weeks and see if my opinion changes.
-Peff
>
> We could enhance this with an option that tells the command to
> check if there is no local change, and automatically fast
> forward when you are truly behind. But I ripped out that change
> because I was unsure what the right way should be to allow users
> to control it (issues include that checkout should not become
> automatically interactive).
>
> This is hot off the press and I know it tends to be a bit too
> loud. It is based on Daniel's "git checkout in C" with Dscho's
> lock_file fix.
>
> ---
>
> builtin-checkout.c | 136 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 136 insertions(+), 0 deletions(-)
>
> diff --git a/builtin-checkout.c b/builtin-checkout.c
> index 59a0ef4..9370ba0 100644
> --- a/builtin-checkout.c
> +++ b/builtin-checkout.c
> @@ -12,6 +12,7 @@
> #include "branch.h"
> #include "diff.h"
> #include "revision.h"
> +#include "remote.h"
>
> static const char * const checkout_usage[] = {
> "git checkout [options] <branch>",
> @@ -290,6 +291,139 @@ static int merge_working_tree(struct checkout_opts *opts,
> return 0;
> }
>
> +/*
> + * We really should allow cb_data... Yuck
> + */
> +static const char *branch_name;
> +static int branch_name_len;
> +static char *found_remote;
> +static char *found_merge;
> +static int read_branch_config(const char *var, const char *value)
> +{
> + const char *name;
> + if (prefixcmp(var, "branch."))
> + return 0; /* not ours */
> + name = var + strlen("branch.");
> + if (strncmp(name, branch_name, branch_name_len) ||
> + name[branch_name_len] != '.')
> + return 0; /* not ours either */
> + if (!strcmp(name + branch_name_len, ".remote")) {
> + /*
> + * Yeah, I know Christian's clean-up should
> + * be used here, but the topic is based on an
> + * older fork point.
> + */
> + if (!value)
> + return error("'%s' not string", var);
> + found_remote = xstrdup(value);
> + return 0;
> + }
> + if (!strcmp(name + branch_name_len, ".merge")) {
> + if (!value)
> + return error("'%s' not string", var);
> + found_merge = xstrdup(value);
> + return 0;
> + }
> + return 0; /* not ours */
> +}
> +
> +static int find_build_base(const char *ours, char **base)
> +{
> + struct remote *remote;
> + struct refspec spec;
> +
> + *base = NULL;
> +
> + branch_name = ours + strlen("refs/heads/");
> + branch_name_len = strlen(branch_name);
> + found_remote = NULL;
> + found_merge = NULL;
> + git_config(read_branch_config);
> +
> + if (!found_remote || !found_merge) {
> + cleanup:
> + free(found_remote);
> + free(found_merge);
> + return 0;
> + }
> +
> + remote = remote_get(found_remote);
> + memset(&spec, 0, sizeof(spec));
> + spec.src = found_merge;
> + if (remote_find_tracking(remote, &spec))
> + goto cleanup;
> + *base = spec.dst;
> + return 1;
> +}
> +
> +static void adjust_to_tracking(struct branch_info *new, struct checkout_opts *opts)
> +{
> + /*
> + * We have switched to a new branch; is it building on
> + * top of another branch, and if so does that other branch
> + * have changes we do not have yet?
> + */
> + char *base;
> + unsigned char sha1[20];
> + struct commit *ours, *theirs;
> + const char *msgfmt;
> + char symmetric[84];
> + int show_log;
> +
> + if (!resolve_ref(new->path, sha1, 1, NULL))
> + return;
> + ours = lookup_commit(sha1);
> +
> + if (!find_build_base(new->path, &base))
> + return;
> +
> + sprintf(symmetric, "%s", sha1_to_hex(sha1));
> +
> + /*
> + * Ok, it is tracking base; is it ahead of us?
> + */
> + if (!resolve_ref(base, sha1, 1, NULL))
> + return;
> + theirs = lookup_commit(sha1);
> +
> + sprintf(symmetric + 40, "...%s", sha1_to_hex(sha1));
> +
> + if (!hashcmp(sha1, ours->object.sha1))
> + return; /* we are the same */
> +
> + show_log = 1;
> + if (in_merge_bases(theirs, &ours, 1)) {
> + msgfmt = "You are ahead of the tracked branch '%s'\n";
> + show_log = 0;
> + }
> + else if (in_merge_bases(ours, &theirs, 1))
> + msgfmt = "Your branch can be fast-forwarded to the tracked branch '%s'\n";
> + else
> + msgfmt = "Both your branch and the tracked branch '%s' have own changes, you would eventually need to merge\n";
> +
> + if (!prefixcmp(base, "refs/remotes/"))
> + base += strlen("refs/remotes/");
> + fprintf(stderr, msgfmt, base);
> +
> + if (show_log) {
> + const char *args[32];
> + int ac;
> +
> + ac = 0;
> + args[ac++] = "log";
> + args[ac++] = "--pretty=oneline";
> + args[ac++] = "--abbrev-commit";
> + args[ac++] = "--left-right";
> + args[ac++] = "--boundary";
> + args[ac++] = symmetric;
> + args[ac++] = "--";
> + args[ac] = NULL;
> +
> + run_command_v_opt(args, RUN_GIT_CMD);
> + }
> +}
> +
> +
> static void update_refs_for_switch(struct checkout_opts *opts,
> struct branch_info *old,
> struct branch_info *new)
> @@ -332,6 +466,8 @@ static void update_refs_for_switch(struct checkout_opts *opts,
> }
> remove_branch_state();
> strbuf_release(&msg);
> + if (new->path)
> + adjust_to_tracking(new, opts);
> }
>
> static int switch_branches(struct checkout_opts *opts,
-
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