On Thu, Feb 3, 2022 at 9:38 AM Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> wrote:
>
> On Thu, Feb 03 2022, Elijah Newren wrote:
>
[...]
> > But that makes --write-tree a mandatory argument when trying to use
> > that mode, right? If so, that is not a simpler way to do what I'm
> > trying to do at all; it breaks my intended usage.
> >
> > --write-tree is a documentation-only construct that users should never
> > have to pass.
> >
> > Also, what happens if we remove the --trivial-merge flag and its whole
> > mode after a sufficient deprecation period? Would the --write-tree
> > parameter remain required in your model to select the only existing
> > mode, simply due to us having gone through a transition period?
>
> You can have your cake and eat it too by running parse_optionss() N
> number of times. Although perhaps in this case the end result isn't
> worth it.
>
> I was hoping this could be a simpler case of a subcommand dispatch, and
> perhaps it can still be generalized to that.
>
> If the "trivial" mode never takes options and always 3 argv elements, we
> could just run parse_options() for it with no options, after checking
> that we have 3 arguments, and none start with '-'.
>
> But the below is a generalization of this I tried out just now, it
> passes all your tests, and means that whenever you add new options you
> don't need to keep saying "no, not with the trivial mode" for each one.
>
> Basically we run parse_options() once with the full set of options, and
> save away argc/argv (note the lack of strvec_clear() there, that's a
> TODO memory leak).
>
> Then we've got a o.mode, which along with argc is the *only* thing we
> pay attention to at that point.
>
> Then we dispatch to the "trivial" or "write" functions, which do
> parse_options() again, this time with only their options.
>
> It means that e.g. this now works as expected:
>
> ./git merge-tree --trivial-merge -z origin/{master,next,seen}
> error: unknown switch `z'
> usage: git merge-tree [--trivial-merge] <base-tree> <branch1> <branch2>
>
> --trivial-merge do a trivial merge only
>
> I.e. we error out, with your verison we'll just ignore the -z.
>
> Your "--trivial-merge is incompatible with all other options" doesn't
> work as you expect, and is buggy whether you want to go this route or
> not, as the added tests show.
>
> Basically it does nothing at all. Because if you add --foo we'll die
> before we get there, parse_options() will die for us.
>
> But if you do --trivial-merge -z your argc/argv will be trimmed, because
> -z is a known option. So your check is doing nothing.
Gah, good catch. How did I get the check reversed?? I know I tested
it at one point. Anyway, this fixes it:
diff --git a/builtin/merge-tree.c b/builtin/merge-tree.c
index 58c0ddc5a3..fb25e3d10d 100644
--- a/builtin/merge-tree.c
+++ b/builtin/merge-tree.c
@@ -505,19 +505,22 @@ int cmd_merge_tree(int argc, const char **argv, const cha
r *prefix)
};
/* Parse arguments */
- original_argc = argc;
+ original_argc = argc - 1; /* ignoring program name, i.e. argv[0] */
argc = parse_options(argc, argv, prefix, mt_options,
merge_tree_usage, PARSE_OPT_STOP_AT_NON_OPTION);
if (o.mode) {
expected_remaining_argc = (o.mode == 'w' ? 2 : 3);
if (argc != expected_remaining_argc)
usage_with_options(merge_tree_usage, mt_options);
+ if (o.mode == 't')
+ /* Removal of `--trivial-merge` is expected */
+ original_argc_options--;
} else {
if (argc < 2 || argc > 3)
usage_with_options(merge_tree_usage, mt_options);
o.mode = (argc == 2 ? 'w' : 't');
}
- if (o.mode == 't' && original_argc < argc)
+ if (o.mode == 't' && argc < original_argc)
die(_("--trivial-merge is incompatible with all other
options"));
/* Do the relevant type of merge */
and results in this error being shown when any other option is listed
with --trivial-merge.
> So, here it is in all its glory :) A bit nasty for sure, but IMO
> preferrable to an ever expanding list of "X isn't compatible with A".
Agreed...on both counts. :-)
> diff --git a/builtin/merge-tree.c b/builtin/merge-tree.c
> index 58c0ddc5a32..1d47912816d 100644
> --- a/builtin/merge-tree.c
> +++ b/builtin/merge-tree.c
> @@ -12,6 +12,7 @@
> #include "exec-cmd.h"
> #include "merge-blobs.h"
> #include "quote.h"
> +#include "strvec.h"
>
> static int line_termination = '\n';
>
> @@ -371,13 +372,66 @@ static void *get_tree_descriptor(struct repository *r,
> return buf;
> }
>
> -static int trivial_merge(const char *base,
> - const char *branch1,
> - const char *branch2)
> +struct merge_tree_options {
> + int mode;
> + int allow_unrelated_histories;
> + int show_messages;
> + int exclude_modes_oids_stages;
> +};
> +
> +#define BUILTIN_MERGE_TREE_USAGE_WRITE \
> + N_("git merge-tree [--write-tree] [<options>] <branch1> <branch2>")
> +#define BUILTIN_MERGE_TREE_USAGE_TRIVIAL \
> + N_("git merge-tree [--trivial-merge] <base-tree> <branch1> <branch2>")
> +
> +#define BUILTIN_MERGE_TREE_OPT_CMDMODE_TRIVIAL \
> + OPT_CMDMODE(0, "trivial-merge", &o.mode, \
> + N_("do a trivial merge only"), 't')
> +
> +#define BUILTIN_MERGE_TREE_OPT_CMDMODE_WRITE \
> + OPT_CMDMODE(0, "write-tree", &o.mode, \
> + N_("do a real merge instead of a trivial merge"), \
> + 'w')
> +
> +#define BUILTIN_MERGE_TREE_OPT_WRITE \
> + BUILTIN_MERGE_TREE_OPT_CMDMODE_WRITE, \
> + OPT_BOOL(0, "messages", &o.show_messages, \
> + N_("also show informational/conflict messages")), \
> + OPT_SET_INT('z', NULL, &line_termination, \
> + N_("separate paths with the NUL character"), '\0'), \
> + OPT_BOOL_F('l', "exclude-modes-oids-stages", \
> + &o.exclude_modes_oids_stages, \
> + N_("list conflicted files without modes/oids/stages"), \
> + PARSE_OPT_NONEG), \
> + OPT_BOOL_F(0, "allow-unrelated-histories", \
> + &o.allow_unrelated_histories, \
> + N_("allow merging unrelated histories"), \
> + PARSE_OPT_NONEG)
> +
> +static int trivial_merge(int argc, const char **argv, const char *prefix)
> {
> struct repository *r = the_repository;
> struct tree_desc t[3];
> void *buf1, *buf2, *buf3;
> + struct merge_tree_options o = { 0 };
> + const char * const usage[] = {
> + BUILTIN_MERGE_TREE_USAGE_TRIVIAL,
> + NULL,
> + };
> + struct option options[] = {
> + BUILTIN_MERGE_TREE_OPT_CMDMODE_TRIVIAL,
> + OPT_END()
> + };
> + const char *base, *branch1, *branch2;
> +
> + argc = parse_options(argc, argv, prefix, options, usage,
> + PARSE_OPT_STOP_AT_NON_OPTION);
> + if (argc != 3)
> + BUG("should have ensured remaining argc == 3 already! Got %d", argc);
> +
> + base = argv[0];
> + branch1 = argv[1];
> + branch2 = argv[2];;
>
> buf1 = get_tree_descriptor(r, t+0, base);
> buf2 = get_tree_descriptor(r, t+1, branch1);
> @@ -391,24 +445,34 @@ static int trivial_merge(const char *base,
> return 0;
> }
>
> -struct merge_tree_options {
> - int mode;
> - int allow_unrelated_histories;
> - int show_messages;
> - int exclude_modes_oids_stages;
> -};
> -
> -static int real_merge(struct merge_tree_options *o,
> - const char *branch1, const char *branch2,
> - const char *prefix)
> +static int real_merge(int argc, const char **argv, const char *prefix)
> {
> struct commit *parent1, *parent2;
> struct commit_list *common;
> struct commit_list *merge_bases = NULL;
> struct commit_list *j;
> + struct merge_tree_options o = { .show_messages = 1 };
> struct merge_options opt;
> struct merge_result result = { 0 };
>
> + const char * const usage[] = {
> + BUILTIN_MERGE_TREE_USAGE_WRITE,
> + NULL,
> + };
> + struct option options[] = {
> + BUILTIN_MERGE_TREE_OPT_CMDMODE_WRITE,
> + BUILTIN_MERGE_TREE_OPT_WRITE,
> + OPT_END()
> + };
> + const char *branch1, *branch2;
> +
> + argc = parse_options(argc, argv, prefix, options, usage,
> + PARSE_OPT_STOP_AT_NON_OPTION);
> + if (argc != 2)
> + BUG("should have ensured remaining argc == 2 already! Got %d", argc);
> + branch1 = argv[0];
> + branch2 = argv[1];
> +
> parent1 = get_merge_parent(branch1);
> if (!parent1)
> help_unknown_ref(branch1, "merge-tree",
> @@ -431,7 +495,7 @@ static int real_merge(struct merge_tree_options *o,
> * merge_incore_recursive in merge-ort.h
> */
> common = get_merge_bases(parent1, parent2);
> - if (!common && !o->allow_unrelated_histories)
> + if (!common && !o.allow_unrelated_histories)
> die(_("refusing to merge unrelated histories"));
> for (j = common; j; j = j->next)
> commit_list_insert(j->item, &merge_bases);
> @@ -440,8 +504,8 @@ static int real_merge(struct merge_tree_options *o,
> if (result.clean < 0)
> die(_("failure to merge"));
>
> - if (o->show_messages == -1)
> - o->show_messages = !result.clean;
> + if (o.show_messages == -1)
> + o.show_messages = !result.clean;
>
> puts(oid_to_hex(&result.tree->object.oid));
> if (!result.clean) {
> @@ -453,7 +517,7 @@ static int real_merge(struct merge_tree_options *o,
> for (i = 0; i < conflicted_files.nr; i++) {
> const char *name = conflicted_files.items[i].string;
> struct stage_info *c = conflicted_files.items[i].util;
> - if (!o->exclude_modes_oids_stages)
> + if (!o.exclude_modes_oids_stages)
> printf("%06o %s %d\t",
> c->mode, oid_to_hex(&c->oid), c->stage);
> else if (last && !strcmp(last, name))
> @@ -464,7 +528,7 @@ static int real_merge(struct merge_tree_options *o,
> }
> string_list_clear(&conflicted_files, 1);
> }
> - if (o->show_messages) {
> + if (o.show_messages) {
> putchar(line_termination);
> merge_display_update_messages(&opt, &result, stdout);
> }
> @@ -474,40 +538,32 @@ static int real_merge(struct merge_tree_options *o,
>
> int cmd_merge_tree(int argc, const char **argv, const char *prefix)
> {
> - struct merge_tree_options o = { .show_messages = -1 };
> + struct merge_tree_options o;
> int expected_remaining_argc;
> - int original_argc;
> -
> + int original_argc = argc;
> + struct strvec original_args = STRVEC_INIT;
> const char * const merge_tree_usage[] = {
> - N_("git merge-tree [--write-tree] [<options>] <branch1> <branch2>"),
> - N_("git merge-tree [--trivial-merge] <base-tree> <branch1> <branch2>"),
> + BUILTIN_MERGE_TREE_USAGE_WRITE,
> + BUILTIN_MERGE_TREE_USAGE_TRIVIAL,
> NULL
> };
> struct option mt_options[] = {
> - OPT_CMDMODE(0, "write-tree", &o.mode,
> - N_("do a real merge instead of a trivial merge"),
> - 'w'),
> - OPT_CMDMODE(0, "trivial-merge", &o.mode,
> - N_("do a trivial merge only"), 't'),
> - OPT_BOOL(0, "messages", &o.show_messages,
> - N_("also show informational/conflict messages")),
> - OPT_SET_INT('z', NULL, &line_termination,
> - N_("separate paths with the NUL character"), '\0'),
> - OPT_BOOL_F('l', "exclude-modes-oids-stages",
> - &o.exclude_modes_oids_stages,
> - N_("list conflicted files without modes/oids/stages"),
> - PARSE_OPT_NONEG),
> - OPT_BOOL_F(0, "allow-unrelated-histories",
> - &o.allow_unrelated_histories,
> - N_("allow merging unrelated histories"),
> - PARSE_OPT_NONEG),
> + BUILTIN_MERGE_TREE_OPT_CMDMODE_TRIVIAL,
> + BUILTIN_MERGE_TREE_OPT_CMDMODE_WRITE,
> + BUILTIN_MERGE_TREE_OPT_WRITE,
> OPT_END()
> };
>
> + /* We only care about deciding "o.mode" here */
> + o.mode = 0;
> + /*
> + * We need our original argv, and
> + * PARSE_OPT_KEEP_{ARGV0,UNKNOWN} would do the wrong thing
> + */
> + strvec_pushv(&original_args, argv);
> /* Parse arguments */
> - original_argc = argc;
> argc = parse_options(argc, argv, prefix, mt_options,
> - merge_tree_usage, PARSE_OPT_STOP_AT_NON_OPTION);
> + merge_tree_usage, 0);
> if (o.mode) {
> expected_remaining_argc = (o.mode == 'w' ? 2 : 3);
> if (argc != expected_remaining_argc)
> @@ -517,12 +573,10 @@ int cmd_merge_tree(int argc, const char **argv, const char *prefix)
> usage_with_options(merge_tree_usage, mt_options);
> o.mode = (argc == 2 ? 'w' : 't');
> }
> - if (o.mode == 't' && original_argc < argc)
> - die(_("--trivial-merge is incompatible with all other options"));
>
> /* Do the relevant type of merge */
> if (o.mode == 'w')
> - return real_merge(&o, argv[0], argv[1], prefix);
> + return real_merge(original_argc, original_args.v, prefix);
> else
> - return trivial_merge(argv[0], argv[1], argv[2]);
> + return trivial_merge(original_argc, original_args.v, prefix);
> }
Yeah, that's waaay more complex than my code which basically just
needs 6 lines to check the incompatibility; the basic patch for that
part (going back to before this patch we're commenting on) was just:
+ original_argc = argc - 1; /* ignore program name, i.e. argv[0] */
...
+ if (o.mode == 't')
+ /* Removal of `--trivial-merge` is expected */
+ original_argc_options--;
...
+ if (o.mode == 't' && argc < original_argc)
+ die(_("--trivial-merge is incompatible with all other options"));
> diff --git a/t/t4301-merge-tree-write-tree.sh b/t/t4301-merge-tree-write-tree.sh
> index 4de089d976d..749bdb6862d 100755
> --- a/t/t4301-merge-tree-write-tree.sh
> +++ b/t/t4301-merge-tree-write-tree.sh
> @@ -92,6 +92,18 @@ test_expect_success 'Barf on too many arguments' '
> grep "^usage: git merge-tree" expect
> '
>
> +for opt in $(git merge-tree --git-completion-helper-all)
> +do
> + if test $opt = "--trivial-merge" || test $opt = "--write-tree"
> + then
> + continue
> + fi
> +
> + test_expect_success "usage: --trivial-merge is incompatible with $opt" '
> + test_expect_code 129 git merge-tree --trivial-merge $opt side1 side2 side3
> + '
> +done
Yep, I was clearly missing an important testcase. Thanks for
providing one and for pointing out the error in my patch! Very cool.
