diff.[ch]: have diff_free() call clear_pathspec(opts.pathspec)

Have the diff_free() function call clear_pathspec(). Since the
diff_flush() function calls this all its callers can be simplified to
rely on it instead.

When I added the diff_free() function in e900d494dcf (diff: add an API
for deferred freeing, 2021-02-11) I simply missed this, or wasn't
interested in it. Let's consolidate this now. This means that any
future callers (and I've got revision.c in mind) that embed a "struct
diff_options" can simply call diff_free() instead of needing know that
it has an embedded pathspec.

This does fix a bunch of leaks, but I can't mark any test here as
passing under the SANITIZE=leak testing mode because in
886e1084d78 (builtin/: add UNLEAKs, 2017-10-01) an UNLEAK(rev) was
added, which plasters over the memory
leak. E.g. "t4011-diff-symlink.sh" would report fewer leaks with this
fix, but because of the UNLEAK() reports none.

I'll eventually loop around to removing that UNLEAK(rev) annotation as
I'll fix deeper issues with the revisions API leaking. This is one
small step on the way there, a new freeing function in revisions.c
will want to call this diff_free().

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

5 files changed, 4 insertions, 9 deletions

diff --git a/add-interactive.c b/add-interactive.c
index 6498ae196f..e1ab39cce3 100644
--- a/add-interactive.c
+++ b/add-interactive.c
@@ -797,14 +797,14 @@ static int run_revert(struct add_i_state *s, const struct pathspec *ps,
 	diffopt.flags.override_submodule_config = 1;
 	diffopt.repo = s->r;
 
-	if (do_diff_cache(&oid, &diffopt))
+	if (do_diff_cache(&oid, &diffopt)) {
+		diff_free(&diffopt);
 		res = -1;
-	else {
+	} else {
 		diffcore_std(&diffopt);
 		diff_flush(&diffopt);
 	}
 	free(paths);
-	clear_pathspec(&diffopt.pathspec);
 
 	if (!res && write_locked_index(s->r->index, &index_lock,
 				       COMMIT_LOCK) < 0)
diff --git a/blame.c b/blame.c
index 206c295660..401990726e 100644
--- a/blame.c
+++ b/blame.c
@@ -1403,7 +1403,6 @@ static struct blame_origin *find_origin(struct repository *r,
 		}
 	}
 	diff_flush(&diff_opts);
-	clear_pathspec(&diff_opts.pathspec);
 	return porigin;
 }
 
@@ -1447,7 +1446,6 @@ static struct blame_origin *find_rename(struct repository *r,
 		}
 	}
 	diff_flush(&diff_opts);
-	clear_pathspec(&diff_opts.pathspec);
 	return porigin;
 }
 
@@ -2328,7 +2326,6 @@ static void find_copy_in_parent(struct blame_scoreboard *sb,
 	} while (unblamed);
 	target->suspects = reverse_blame(leftover, NULL);
 	diff_flush(&diff_opts);
-	clear_pathspec(&diff_opts.pathspec);
 }
 
 /*
diff --git a/builtin/reset.c b/builtin/reset.c
index b97745ee94..24968dd628 100644
--- a/builtin/reset.c
+++ b/builtin/reset.c
@@ -274,7 +274,6 @@ static int read_from_tree(const struct pathspec *pathspec,
 		return 1;
 	diffcore_std(&opt);
 	diff_flush(&opt);
-	clear_pathspec(&opt.pathspec);
 
 	return 0;
 }
diff --git a/diff.c b/diff.c
index c862771a58..0aef3db6e1 100644
--- a/diff.c
+++ b/diff.c
@@ -6345,6 +6345,7 @@ void diff_free(struct diff_options *options)
 
 	diff_free_file(options);
 	diff_free_ignore_regex(options);
+	clear_pathspec(&options->pathspec);
 }
 
 void diff_flush(struct diff_options *options)
diff --git a/notes-merge.c b/notes-merge.c
index b4a3a903e8..7ba40cfb08 100644
--- a/notes-merge.c
+++ b/notes-merge.c
@@ -175,7 +175,6 @@ static struct notes_merge_pair *diff_tree_remote(struct notes_merge_options *o,
 		       oid_to_hex(&mp->remote));
 	}
 	diff_flush(&opt);
-	clear_pathspec(&opt.pathspec);
 
 	*num_changes = len;
 	return changes;
@@ -261,7 +260,6 @@ static void diff_tree_local(struct notes_merge_options *o,
 		       oid_to_hex(&mp->local));
 	}
 	diff_flush(&opt);
-	clear_pathspec(&opt.pathspec);
 }
 
 static void check_notes_merge_worktree(struct notes_merge_options *o)