labeled block statements

compiler/parser/parser.odin

@@ -1058,14 +1058,16 @@ parse_loop_control :: proc(parser: ^Parser, kind: ast.Stmt_Kind) -> ast.Stmt_Id
 }
 
 // A bare `{ ... }` introduces a nested scope. Locals declared inside are not
-// visible after it, and any `defer`s inside it run at the closing brace.
-parse_block_statement :: proc(parser: ^Parser) -> ast.Stmt_Id {
+// visible after it, and any `defer`s inside it run at the closing brace. A labeled
+// `blk: { ... }` can be exited early with `break :blk`.
+parse_block_statement :: proc(parser: ^Parser, label := symbol.INVALID) -> ast.Stmt_Id {
 	start := current(parser).span // the '{'
 	body := parse_block(parser)
 	id := ast.stmt_id(len(parser.module.statements))
 	append(&parser.module.statements, ast.Stmt{
 		kind=.Block,
 		span=start,
+		label=label,
 		body=body,
 		expr=ast.INVALID_EXPR,
 		update=ast.INVALID_STMT,
@@ -1159,6 +1161,12 @@ parse_statement :: proc(parser: ^Parser) -> ast.Stmt_Id {
 	if current(parser).kind == .Left_Brace {
 		return parse_block_statement(parser)
 	}
+	// `blk: { ... }` is a labeled block statement (exitable via `break :blk`). At
+	// statement start, `Identifier ':'` (a single colon, not `::`) opens one.
+	if current(parser).kind == .Identifier && peek(parser).kind == .Colon {
+		label := parse_optional_loop_label(parser)
+		return parse_block_statement(parser, label)
+	}
 
 	if current(parser).kind == .Identifier || current(parser).kind == .Underscore {
 		start_cursor := parser.cursor