parse: make multi-line structure parsing more robust

bshell/parse/syntax/arith.c

@@ -848,6 +848,7 @@ bool parse_arith_expr(
 			case SYM_DOLLAR_LEFT_PAREN:
 			case SYM_AT_LEFT_PAREN:
 			case SYM_AT_LEFT_BRACE:
+			case SYM_LEFT_BRACE:
 				expr.expr_fail = !parse_operand(ctx, &expr);
 				break;
 			default: {

bshell/parse/syntax/block.c

@@ -6,23 +6,44 @@ bool parse_block(struct parse_ctx *ctx, struct ast_node **out)
 		return false;
 	}
 
+	parse_linefeed(ctx);
+
 	struct block_ast_node *block
 		= (struct block_ast_node *)ast_node_create(AST_BLOCK);
 
+	bool ok = true;
 	while (1) {
+		if (parse_symbol(ctx, SYM_RIGHT_BRACE)) {
+			break;
+		}
+
 		parse_linefeed(ctx);
 
+		struct ast_node *stmt = NULL;
+		if (!parse_statement(ctx, &stmt)) {
+			ok = false;
+			break;
+		}
+
+		fx_queue_push_back(&block->n_statements, &stmt->n_entry);
+
 		if (parse_symbol(ctx, SYM_RIGHT_BRACE)) {
 			break;
 		}
 
-		struct ast_node *stmt = NULL;
+		if (!parse_linefeed(ctx) && !parse_symbol(ctx, SYM_SEMICOLON)) {
-		if (!parse_statement(ctx, &stmt)) {
+			report_error(
-			ast_node_destroy((struct ast_node *)block);
+				ctx,
-			return false;
+				"expected `;`, `}`, or linefeed after "
+				"statement");
+			ok = false;
+			break;
+		}
 	}
 
-		fx_queue_push_back(&block->n_statements, &stmt->n_entry);
+	if (!ok) {
+		ast_node_destroy((struct ast_node *)block);
+		block = NULL;
 	}
 
 	*out = (struct ast_node *)block;

bshell/parse/syntax/if-else.c

@@ -5,8 +5,8 @@ static bool add_branch(
 	struct ast_node *cond,
 	struct ast_node *body)
 {
-	struct if_branch_ast_node *branch
+	struct if_branch_ast_node *branch = (struct if_branch_ast_node *)
-		= (struct if_branch_ast_node *)ast_node_create(AST_IF_BRANCH);
+		ast_node_create(AST_IF_BRANCH);
 	if (!branch) {
 		return false;
 	}
@@ -47,8 +47,8 @@ bool parse_if(struct parse_ctx *ctx, struct ast_node **out)
 		return false;
 	}
 
-	struct if_ast_node *if_group
+	struct if_ast_node *if_group = (struct if_ast_node *)ast_node_create(
-		= (struct if_ast_node *)ast_node_create(AST_IF);
+		AST_IF);
 	if (!if_group) {
 		ctx->p_status = BSHELL_ERR_NO_MEMORY;
 		ast_node_destroy(if_cond);
@@ -70,6 +70,13 @@ bool parse_if(struct parse_ctx *ctx, struct ast_node **out)
 		if (parse_keyword(ctx, KW_ELSE)) {
 			done = true;
 		} else if (parse_keyword(ctx, KW_ELSEIF)) {
+			if (!parse_symbol(ctx, SYM_LEFT_PAREN)) {
+				report_error(
+					ctx,
+					"expected `(` after `elseif`");
+				return false;
+			}
+
 			if (!parse_expr(ctx, &cond)) {
 				report_error(
 					ctx,
@@ -77,6 +84,14 @@ bool parse_if(struct parse_ctx *ctx, struct ast_node **out)
 				ast_node_destroy((struct ast_node *)if_group);
 				return false;
 			}
+
+			if (!parse_symbol(ctx, SYM_RIGHT_PAREN)) {
+				report_error(
+					ctx,
+					"expected `)` after elseif-condition");
+				ast_node_destroy(if_cond);
+				return false;
+			}
 		} else {
 			done = true;
 			break;