solver: corner case fixes

- try harder to not change anything during self-upgrade
- also honor locking to packages that where earlier used in
  merging common dependencies
- clarify upgrade applet help messages

src/apk_solver_data.h

@@ -45,6 +45,8 @@ struct apk_solver_package_state {
 	unsigned tag_ok : 1;
 	unsigned tag_preferred : 1;
 	unsigned available : 1;
+	unsigned dependencies_used : 1;
+	unsigned dependencies_merged : 1;
 	unsigned in_changeset : 1;
 	unsigned iif_triggered : 1;
 };

src/solver.c

@@ -329,6 +329,7 @@ static void reconsider_name(struct apk_solver_state *ss, struct apk_name *name)
 		struct apk_package *pkg = p0->pkg;
 
 		/* check if this pkg's dependencies have become unsatisfiable */
+		pkg->ss.dependencies_merged = 0;
 		if (reevaluate_deps) {
 			if (!pkg->ss.available)
 				continue;
@@ -360,6 +361,7 @@ static void reconsider_name(struct apk_solver_state *ss, struct apk_name *name)
 		num_tag_not_ok += !pkg->ss.tag_ok;
 
 		/* merge common dependencies */
+		pkg->ss.dependencies_merged = 1;
 		if (first_candidate == -1)
 			first_candidate = i;
 		for (j = 0; j < pkg->depends->num; j++) {
@@ -377,6 +379,10 @@ static void reconsider_name(struct apk_solver_state *ss, struct apk_name *name)
 	queue_unresolved(ss, name);
 
 	if (first_candidate != -1) {
+		for (i = 0; i < name->providers->num; i++) {
+			struct apk_package *pkg = name->providers->item[i].pkg;
+			pkg->ss.dependencies_used = pkg->ss.dependencies_merged;
+		}
 		/* TODO: could merge versioning bits too */
 		/* propagate down common dependencies */
 		pkg = name->providers->item[first_candidate].pkg;
@@ -418,13 +424,25 @@ static int compare_providers(struct apk_solver_state *ss,
 	if (r)
 		return r;
 
+	/* Prefer those that were in last dependency merging group */
+	r = (int)pkgA->ss.dependencies_used - (int)pkgB->ss.dependencies_used;
+	if (r)
+		return r;
+
+	/* Prefer installed on self-upgrade */
+	solver_flags = pkgA->ss.solver_flags | pkgB->ss.solver_flags;
+	if (db->performing_self_update && !(solver_flags & APK_SOLVERF_UPGRADE)) {
+		r = (pkgA->ipkg != NULL) - (pkgB->ipkg != NULL);
+		if (r)
+			return r;
+	}
+
 	/* Prefer allowed pinning */
 	r = (int)pkgA->ss.tag_ok - (int)pkgB->ss.tag_ok;
 	if (r)
 		return r;
 
 	/* Prefer available */
-	solver_flags = pkgA->ss.solver_flags | pkgB->ss.solver_flags;
 	if (solver_flags & APK_SOLVERF_AVAILABLE) {
 		r = !!(pkgA->repos & db->available_repos) -
 		    !!(pkgB->repos & db->available_repos);
@@ -712,8 +730,6 @@ int apk_solver_solve(struct apk_database *db,
 
 	foreach_dependency(ss, world, discover_names);
 
-	/* FIXME: If filename specified, force to use it */
-
 	dbg_printf("applying world\n");
 	ss->prefer_pinning = 1;
 	ss->solver_flags_inherit = solver_flags;

src/upgrade.c

@@ -60,7 +60,7 @@ int apk_do_self_upgrade(struct apk_database *db, unsigned short solver_flags)
 		goto ret;
 	}
 
-	if (changeset.num_install + changeset.num_remove + changeset.num_adjust == 0)
+	if (changeset.num_total_changes == 0)
 		goto ret;
 
 	if (apk_flags & APK_SIMULATE) {
@@ -130,16 +130,17 @@ static int upgrade_main(void *ctx, struct apk_database *db, int argc, char **arg
 
 static struct apk_option upgrade_options[] = {
 	{ 'a', "available",
-	  "Re-install or downgrade if currently installed package is not "
-	  "currently available from any repository" },
+	  "Resets versioned world dependencies, and changes to prefer "
+	  "replacing or downgrading packages (instead of holding them) "
+	  "if the currently installed package is no longer available "
+	  "from any repository" },
 	{ 0x10000, "no-self-upgrade",
 	  "Do not do early upgrade of 'apk-tools' package" },
 };
 
 static struct apk_applet apk_upgrade = {
 	.name = "upgrade",
-	.help = "Upgrade (or downgrade with -a) the currently installed "
-		"packages to versions available in repositories.",
+	.help = "Upgrade currently installed packages to match repositories.",
 	.open_flags = APK_OPENF_WRITE,
 	.context_size = sizeof(struct upgrade_ctx),
 	.num_options = ARRAY_SIZE(upgrade_options),