while loops

compiler/ast/ast.odin

@@ -120,6 +120,7 @@ Stmt_Kind :: enum u8 {
 	Return,
 	Expression,
 	If,
+	While,
 }
 
 Stmt :: struct {
@@ -133,8 +134,11 @@ Stmt :: struct {
 	// `If` statements use `expr` as the condition, `body` as the then-block, and
 	// `else_body` as the else-block. An `else if` chain is represented as an
 	// `else_body` holding a single nested `If` statement.
+	// `While` statements use `expr` as the condition, `body` as the loop body,
+	// and `update` as the optional post-iteration statement.
 	body:       []Stmt_Id,
 	else_body:  []Stmt_Id,
+	update:     Stmt_Id,
 	diagnostic: source.Diagnostic_Id,
 }