wallet: we can assume local_alias field is non-null.

We have a migration which ensures this, but then I discovered that did
*not* address channels without an SCID yet.  So fixed the migration, and
simpligied the code.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Author: rustyrussell

wallet/db.c

@@ -1026,7 +1026,7 @@ static struct migration dbmigrations[] = {
     {SQL("ALTER TABLE channels ADD remote_htlc_maximum_msat BIGINT DEFAULT NULL;"), NULL},
     {SQL("ALTER TABLE channels ADD remote_htlc_minimum_msat BIGINT DEFAULT NULL;"), NULL},
     {SQL("ALTER TABLE channels ADD last_stable_connection BIGINT DEFAULT 0;"), NULL},
-    {NULL, migrate_initialize_alias_local},
+    {NULL, NULL}, /* old migrate_initialize_alias_local */
     {SQL("CREATE TABLE addresses ("
 	 "  keyidx BIGINT,"
 	 "  addrtype INTEGER)"), NULL},
@@ -1044,6 +1044,7 @@ static struct migration dbmigrations[] = {
     {NULL, migrate_initialize_channel_htlcs_wait_indexes_and_fixup_forwards},
     {SQL("ALTER TABLE channel_funding_inflights ADD i_sent_sigs INTEGER DEFAULT 0"), NULL},
     {SQL("ALTER TABLE channels ADD old_scids BLOB DEFAULT NULL;"), NULL},
+    {NULL, migrate_initialize_alias_local},
 };
 
 /**
@@ -2013,8 +2014,7 @@ static void migrate_initialize_alias_local(struct lightningd *ld,
 	u64 *ids = tal_arr(tmpctx, u64, 0);
 
 	stmt = db_prepare_v2(db, SQL("SELECT id FROM channels"
-				     " WHERE scid IS NOT NULL"
-				     " AND alias_local IS NULL;"));
+				     " WHERE alias_local IS NULL;"));
 	db_query_prepared(stmt);
 	while (db_step(stmt))
 		tal_arr_expand(&ids, db_col_u64(stmt, "id"));

wallet/test/run-wallet.c

@@ -1794,6 +1794,7 @@ static bool test_channel_crud(struct lightningd *ld, const tal_t *ctx)
 	struct pubkey pk;
 	struct node_id id;
 	struct changed_htlc *last_commit;
+	struct short_channel_id local_alias;
 	secp256k1_ecdsa_signature *sig = tal(w, secp256k1_ecdsa_signature);
 	u8 *scriptpubkey = tal_arr(ctx, u8, 100);
 	secp256k1_ecdsa_signature *node_sig1 = tal(w, secp256k1_ecdsa_signature);
@@ -1850,6 +1851,8 @@ static bool test_channel_crud(struct lightningd *ld, const tal_t *ctx)
 	/* Init channel inflights */
 	list_head_init(&c1.inflights);
 	c1.type = type;
+	local_alias = random_scid();
+	c1.alias[LOCAL] = &local_alias;
 
 	db_begin_transaction(w->db);
 	CHECK(!wallet_err);

wallet/wallet.c

@@ -1819,7 +1819,8 @@ static struct channel *wallet_stmt2channel(struct wallet *w, struct db_stmt *stm
 
 	scid = db_col_optional_scid(tmpctx, stmt, "scid");
 	old_scids = db_col_short_channel_id_arr(tmpctx, stmt, "old_scids");
-	alias[LOCAL] = db_col_optional_scid(tmpctx, stmt, "alias_local");
+	alias[LOCAL] = tal(tmpctx, struct short_channel_id);
+	*alias[LOCAL] = db_col_short_channel_id(stmt, "alias_local");
 	alias[REMOTE] = db_col_optional_scid(tmpctx, stmt, "alias_remote");
 
  	ok &= wallet_shachain_load(w, db_col_u64(stmt, "shachain_remote_id"),
@@ -2099,7 +2100,8 @@ static struct closed_channel *wallet_stmt2closed_channel(const tal_t *ctx,
 	cc->peer_id = db_col_optional(cc, stmt, "p.node_id", node_id);
 	db_col_channel_id(stmt, "full_channel_id", &cc->cid);
 	cc->scid = db_col_optional_scid(cc, stmt, "scid");
-	cc->alias[LOCAL] = db_col_optional_scid(cc, stmt, "alias_local");
+	cc->alias[LOCAL] = tal(cc, struct short_channel_id);
+	*cc->alias[LOCAL] = db_col_short_channel_id(stmt, "alias_local");
 	cc->alias[REMOTE] = db_col_optional_scid(cc, stmt, "alias_remote");
 	cc->opener = db_col_int(stmt, "funder");
 	cc->closer = db_col_int(stmt, "closer");
@@ -2654,11 +2656,7 @@ void wallet_channel_save(struct wallet *w, struct channel *chan)
 	db_bind_amount_msat(stmt, &chan->htlc_minimum_msat);
 	db_bind_amount_msat(stmt, &chan->htlc_maximum_msat);
 
-	if (chan->alias[LOCAL] != NULL)
-		db_bind_short_channel_id(stmt, *chan->alias[LOCAL]);
-	else
-		db_bind_null(stmt);
-
+	db_bind_short_channel_id(stmt, *chan->alias[LOCAL]);
 	if (chan->alias[REMOTE] != NULL)
 		db_bind_short_channel_id(stmt, *chan->alias[REMOTE]);
 	else