read-cache API & users: make discard_index() return void

The discard_index() function has not returned non-zero since
7a51ed66f6 (Make on-disk index representation separate from in-core
one, 2008-01-14), but we've had various code in-tree still acting as
though that might be the case.

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

add-interactive.c

@@ -530,8 +530,8 @@ static int get_modified_files(struct repository *r,
 	struct collection_status s = { 0 };
 	int i;
 
-	if (discard_index(r->index) < 0 ||
-	    repo_read_index_preload(r, ps, 0) < 0)
+	discard_index(r->index);
+	if (repo_read_index_preload(r, ps, 0) < 0)
 		return error(_("could not read index"));
 
 	prefix_item_list_clear(files);
@@ -1156,8 +1156,8 @@ int run_add_i(struct repository *r, const struct pathspec *ps)
 		    _("staged"), _("unstaged"), _("path"));
 	opts.list_opts.header = header.buf;
 
-	if (discard_index(r->index) < 0 ||
-	    repo_read_index(r) < 0 ||
+	discard_index(r->index);
+	if (repo_read_index(r) < 0 ||
 	    repo_refresh_and_write_index(r, REFRESH_QUIET, 0, 1,
 					 NULL, NULL, NULL) < 0)
 		warning(_("could not refresh index"));

add-patch.c

@@ -1750,7 +1750,8 @@ int run_add_p(struct repository *r, enum add_p_mode mode,
 		s.mode = &patch_mode_add;
 	s.revision = revision;
 
-	if (discard_index(r->index) < 0 || repo_read_index(r) < 0 ||
+	discard_index(r->index);
+	if (repo_read_index(r) < 0 ||
 	    (!s.mode->index_only &&
 	     repo_refresh_and_write_index(r, REFRESH_QUIET, 0, 1,
 					  NULL, NULL, NULL) < 0) ||

builtin/merge.c

@@ -390,7 +390,8 @@ static void restore_state(const struct object_id *head,
 	run_command(&cmd);
 
 refresh_cache:
-	if (discard_cache() < 0 || read_cache() < 0)
+	discard_cache();
+	if (read_cache() < 0)
 		die(_("could not read index"));
 }
 

cache.h

@@ -774,7 +774,7 @@ void ensure_full_index(struct index_state *istate);
  */
 int write_locked_index(struct index_state *, struct lock_file *lock, unsigned flags);
 
-int discard_index(struct index_state *);
+void discard_index(struct index_state *);
 void move_index_extensions(struct index_state *dst, struct index_state *src);
 int unmerged_index(const struct index_state *);
 

read-cache.c

@@ -2531,7 +2531,7 @@ int is_index_unborn(struct index_state *istate)
 	return (!istate->cache_nr && !istate->timestamp.sec);
 }
 
-int discard_index(struct index_state *istate)
+void discard_index(struct index_state *istate)
 {
 	/*
 	 * Cache entries in istate->cache[] should have been allocated
@@ -2562,8 +2562,6 @@ int discard_index(struct index_state *istate)
 		mem_pool_discard(istate->ce_mem_pool, should_validate_cache_entries());
 		FREE_AND_NULL(istate->ce_mem_pool);
 	}
-
-	return 0;
 }
 
 /*

sequencer.c

@@ -3564,7 +3564,8 @@ static int do_exec(struct repository *r, const char *command_line)
 	status = run_command(&cmd);
 
 	/* force re-reading of the cache */
-	if (discard_index(r->index) < 0 || repo_read_index(r) < 0)
+	discard_index(r->index);
+	if (repo_read_index(r) < 0)
 		return error(_("could not read index"));
 
 	dirty = require_clean_work_tree(r, "rebase", NULL, 1, 1);
@@ -4029,9 +4030,11 @@ static int do_merge(struct repository *r,
 		ret = run_command(&cmd);
 
 		/* force re-reading of the cache */
-		if (!ret && (discard_index(r->index) < 0 ||
-			     repo_read_index(r) < 0))
-			ret = error(_("could not read index"));
+		if (!ret) {
+			discard_index(r->index);
+			if (repo_read_index(r) < 0)
+				ret = error(_("could not read index"));
+		}
 		goto leave_merge;
 	}
 
@@ -4404,8 +4407,8 @@ void create_autostash(struct repository *r, const char *path)
 		printf(_("Created autostash: %s\n"), buf.buf);
 		if (reset_head(r, &ropts) < 0)
 			die(_("could not reset --hard"));
-		if (discard_index(r->index) < 0 ||
-			repo_read_index(r) < 0)
+		discard_index(r->index);
+		if (repo_read_index(r) < 0)
 			die(_("could not read index"));
 	}
 	strbuf_release(&buf);