From 583579c548a175dc02a81d98ae5531668474e297 Mon Sep 17 00:00:00 2001
From: Brendan Hansen <brendan.f.hansen@gmail.com>
Date: Fri, 21 Apr 2023 20:27:17 -0500
Subject: [PATCH] added: closure by reference (very succeptible to dangling
 pointers)

---
 compiler/include/astnodes.h |  1 +
 compiler/src/checker.c      | 15 +++++++++++++--
 compiler/src/parser.c       |  3 +++
 compiler/src/wasm_emit.c    | 10 ++++++++--
 4 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/compiler/include/astnodes.h b/compiler/include/astnodes.h
index ef896aa6..2f2f7488 100644
--- a/compiler/include/astnodes.h
+++ b/compiler/include/astnodes.h
@@ -1362,6 +1362,7 @@ struct AstCaptureLocal {
     AstTyped *captured_value;
 
     u32 offset;
+    b32 by_reference: 1;
 };
 
 struct AstPolyQuery {
diff --git a/compiler/src/checker.c b/compiler/src/checker.c
index b1ccbed3..1011e8a0 100644
--- a/compiler/src/checker.c
+++ b/compiler/src/checker.c
@@ -2225,9 +2225,20 @@ CheckStatus check_expression(AstTyped** pexpr) {
             YIELD(expr->token->pos, "Waiting to resolve #this_package.");
             break;
 
-        case Ast_Kind_Capture_Local:
-            expr->type = ((AstCaptureLocal *) expr)->captured_value->type;
+        case Ast_Kind_Capture_Local: {
+            AstCaptureLocal *cl = (AstCaptureLocal *) expr;
+            if (cl->by_reference) {
+                if (!is_lval((AstNode *) cl->captured_value)) {
+                    ERROR_(cl->token->pos, "Cannot pass '%b' by pointer because it is not an l-value.", cl->token->text, cl->token->length);
+                }
+
+                expr->type = type_make_pointer(context.ast_alloc, cl->captured_value->type);
+
+            } else {
+                expr->type = cl->captured_value->type;
+            }
             break;
+        }
 
         case Ast_Kind_File_Contents: break;
         case Ast_Kind_Overloaded_Function: break;
diff --git a/compiler/src/parser.c b/compiler/src/parser.c
index f74622be..7f4e5a5f 100644
--- a/compiler/src/parser.c
+++ b/compiler/src/parser.c
@@ -2400,6 +2400,9 @@ static AstCaptureBlock *parse_capture_list(OnyxParser* parser, TokenType end_tok
         if (parser->hit_unexpected_token) break;
 
         AstCaptureLocal *capture = make_node(AstCaptureLocal, Ast_Kind_Capture_Local);
+
+        if (consume_token_if_next(parser, '&')) capture->by_reference = 1;
+
         capture->token = expect_token(parser, Token_Type_Symbol);
 
         bh_arr_push(captures->captures, capture);
diff --git a/compiler/src/wasm_emit.c b/compiler/src/wasm_emit.c
index 4a5273d9..f1d18d9b 100644
--- a/compiler/src/wasm_emit.c
+++ b/compiler/src/wasm_emit.c
@@ -3418,8 +3418,14 @@ EMIT_FUNC(expression, AstTyped* expr) {
             // Populate the block
             bh_arr_each(AstCaptureLocal *, capture, func->captures->captures) {
                 WIL(NULL, WI_LOCAL_GET, capture_block_ptr);
-                emit_expression(mod, &code, (*capture)->captured_value);
-                emit_store_instruction(mod, &code, (*capture)->captured_value->type, (*capture)->offset);
+
+                if ((*capture)->by_reference) {
+                    emit_location(mod, &code, (*capture)->captured_value);
+                } else {
+                    emit_expression(mod, &code, (*capture)->captured_value);
+                }
+
+                emit_store_instruction(mod, &code, (*capture)->type, (*capture)->offset);
             }
             
             local_raw_free(mod->local_alloc, WASM_TYPE_PTR);
-- 
2.25.1