Revert "Deprecate `defer`"

This reverts commit 7e3e245f6809946ea06ef1998bcabb7e0902fbd7.

1 files changed, 34 insertions, 0 deletions

diff --git a/src/compile/statements.c b/src/compile/statements.c
index 2c680b3b..37eff680 100644
--- a/src/compile/statements.c
+++ b/src/compile/statements.c
@@ -84,11 +84,40 @@ static Text_t _compile_statement(env_t *env, ast_t *ast) {
     case Skip: return compile_skip(env, ast);
     case Stop: return compile_stop(env, ast);
     case Pass: return Text(";");
+    case Defer: {
+        ast_t *body = Match(ast, Defer)->body;
+        Table_t closed_vars = get_closed_vars(env, NULL, body);
+
+        static int defer_id = 0;
+        env_t *defer_env = fresh_scope(env);
+        Text_t code = EMPTY_TEXT;
+        for (int64_t i = 0; i < closed_vars.entries.length; i++) {
+            struct {
+                const char *name;
+                binding_t *b;
+            } *entry = closed_vars.entries.data + closed_vars.entries.stride * i;
+            if (entry->b->type->tag == ModuleType) continue;
+            if (Text$starts_with(entry->b->code, Text("userdata->"), NULL)) {
+                Table$str_set(defer_env->locals, entry->name, entry->b);
+            } else {
+                Text_t defer_name = Texts("defer$", ++defer_id, "$", entry->name);
+                defer_id += 1;
+                code = Texts(code, compile_declaration(entry->b->type, defer_name), " = ", entry->b->code, ";\n");
+                set_binding(defer_env, entry->name, entry->b->type, defer_name);
+            }
+        }
+        env->deferred = new (deferral_t, .defer_env = defer_env, .block = body, .next = env->deferred);
+        return code;
+    }
     case Return: {
         if (!env->fn) code_err(ast, "This return statement is not inside any function");
         ast_t *ret = Match(ast, Return)->value;
 
         Text_t code = EMPTY_TEXT;
+        for (deferral_t *deferred = env->deferred; deferred; deferred = deferred->next) {
+            code = Texts(code, compile_statement(deferred->defer_env, deferred->block));
+        }
+
         type_t *ret_type = get_function_return_type(env, env->fn);
         if (ret) {
             if (ret_type->tag == VoidType || ret_type->tag == AbortType)
@@ -104,6 +133,11 @@ static Text_t _compile_statement(env_t *env, ast_t *ast) {
                 }
             }
             Text_t value = compile_to_type(env, ret, ret_type);
+            if (env->deferred) {
+                code = Texts(compile_declaration(ret_type, Text("ret")), " = ", value, ";\n", code);
+                value = Text("ret");
+            }
+
             return Texts(code, "return ", value, ";");
         } else {
             if (ret_type->tag != VoidType)