revisions API: extend the nascent REV_INFO_INIT macro

Have the REV_INFO_INIT macro added in [1] declare more members of
"struct rev_info" that we can initialize statically, and have
repo_init_revisions() do so with the memcpy(..., &blank) idiom
introduced in [2].

As the comment for the "REV_INFO_INIT" macro notes this still isn't
sufficient to initialize a "struct rev_info" for use yet. But we are
getting closer to that eventual goal.

Even though we can't fully initialize a "struct rev_info" with
REV_INFO_INIT it's useful for readability to clearly separate those
things that we can statically initialize, and those that we can't.

This change could replace the:

	list_objects_filter_init(&revs->filter);

In the repo_init_revisions() with this line, at the end of the
REV_INFO_INIT deceleration in revisions.h:

	.filter = LIST_OBJECTS_FILTER_INIT, \

But doing so would produce a minor conflict with an outstanding
topic[3]. Let's skip that for now. I have follow-ups to initialize
more of this statically, e.g. changes to get rid of grep_init(). We
can initialize more members with the macro in a future series.

1. f196c1e (revisions API users: use release_revisions() needing
   REV_INFO_INIT, 2022-04-13)
2. 5726a6b (*.c *_init(): define in terms of corresponding *_INIT
   macro, 2021-07-01)
3. https://lore.kernel.org/git/265b292ed5c2de19b7118dfe046d3d9d932e2e89.1667901510.git.ps@pks.im/

Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]>
Signed-off-by: Taylor Blau <[email protected]>

Author: avar

revision.c

@@ -1865,30 +1865,15 @@ void repo_init_revisions(struct repository *r,
 			 struct rev_info *revs,
 			 const char *prefix)
 {
-	memset(revs, 0, sizeof(*revs));
+	struct rev_info blank = REV_INFO_INIT;
+	memcpy(revs, &blank, sizeof(*revs));
 
 	revs->repo = r;
-	revs->abbrev = DEFAULT_ABBREV;
-	revs->simplify_history = 1;
 	revs->pruning.repo = r;
-	revs->pruning.flags.recursive = 1;
-	revs->pruning.flags.quick = 1;
 	revs->pruning.add_remove = file_add_remove;
 	revs->pruning.change = file_change;
 	revs->pruning.change_fn_data = revs;
-	revs->sort_order = REV_SORT_IN_GRAPH_ORDER;
-	revs->dense = 1;
 	revs->prefix = prefix;
-	revs->max_age = -1;
-	revs->max_age_as_filter = -1;
-	revs->min_age = -1;
-	revs->skip_count = -1;
-	revs->max_count = -1;
-	revs->max_parents = -1;
-	revs->expand_tabs_in_log = -1;
-
-	revs->commit_format = CMIT_FMT_DEFAULT;
-	revs->expand_tabs_in_log_default = 8;
 
 	grep_init(&revs->grep_filter, revs->repo);
 	revs->grep_filter.status_only = 1;

revision.h

@@ -357,7 +357,23 @@ struct rev_info {
  * called before release_revisions() the "struct rev_info" can be left
  * uninitialized.
  */
-#define REV_INFO_INIT { 0 }
+#define REV_INFO_INIT { \
+	.abbrev = DEFAULT_ABBREV, \
+	.simplify_history = 1, \
+	.pruning.flags.recursive = 1, \
+	.pruning.flags.quick = 1, \
+	.sort_order = REV_SORT_IN_GRAPH_ORDER, \
+	.dense = 1, \
+	.max_age = -1, \
+	.max_age_as_filter = -1, \
+	.min_age = -1, \
+	.skip_count = -1, \
+	.max_count = -1, \
+	.max_parents = -1, \
+	.expand_tabs_in_log = -1, \
+	.commit_format = CMIT_FMT_DEFAULT, \
+	.expand_tabs_in_log_default = 8, \
+}
 
 /**
  * Initialize a rev_info structure with default values. The third parameter may