From feb9b6159ef0c9b41c0dcefe319fc68fe645a8e7 Mon Sep 17 00:00:00 2001
From: gingerBill <gingerBill@users.noreply.github.com>
Date: Mon, 29 Jun 2026 11:06:34 +0100
Subject: [PATCH] Fix `pkg.Constant.field` union access

---
 src/exact_value.cpp        | 16 ++++++++++++++++
 src/llvm_backend_const.cpp | 18 ++++++++++++++++--
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/src/exact_value.cpp b/src/exact_value.cpp
index f232f95e0..184a8f2e4 100644
--- a/src/exact_value.cpp
+++ b/src/exact_value.cpp
@@ -32,6 +32,22 @@ enum ExactValueKind {
 	ExactValue_Count,
 };
 
+gb_global char const *exact_value_kind_string[ExactValue_Count] = {
+	"Invalid",
+
+	"Bool",
+	"String",
+	"Integer",
+	"Float",
+	"Complex",
+	"Quaternion",
+	"Pointer",
+	"Compound",
+	"Procedure",
+	"Typeid",
+	"String16",
+};
+
 struct ExactValue {
 	ExactValueKind kind;
 	union {
diff --git a/src/llvm_backend_const.cpp b/src/llvm_backend_const.cpp
index be036f553..0973d49d5 100644
--- a/src/llvm_backend_const.cpp
+++ b/src/llvm_backend_const.cpp
@@ -972,6 +972,7 @@ gb_internal lbValue lb_const_value(lbModule *m, Type *type, ExactValue value, Ty
 					if (cl->elems.count == 0) {
 						return lb_const_nil(m, original_type);
 					}
+					value_type = type_of_expr(value.value_compound);
 				} else if (value.kind == ExactValue_Invalid) {
 					return lb_const_nil(m, original_type);
 				}
@@ -983,18 +984,31 @@ gb_internal lbValue lb_const_value(lbModule *m, Type *type, ExactValue value, Ty
 
 			i64 block_size = bt->Union.variant_block_size;
 
-			if (are_types_identical(value_type, original_type)) {
+			while (are_types_identical(value_type, original_type)) {
 				if (value.kind == ExactValue_Compound) {
 					ast_node(cl, CompoundLit, value.value_compound);
 					if (cl->elems.count == 0) {
 						return lb_const_nil(m, original_type);
 					}
+
+					value_type = type_of_expr(value.value_compound);
+					if (!are_types_identical(value_type, original_type)) {
+						break;
+					}
+
+					GB_PANIC("%s --> %s vs %s",
+					         expr_to_string(value.value_compound),
+					         temp_canonical_string(value_type), temp_canonical_string(original_type));
+
 				} else if (value.kind == ExactValue_Invalid) {
 					return lb_const_nil(m, original_type);
 				}
 
-				GB_PANIC("%s vs %s", type_to_string(value_type), type_to_string(original_type));
+				GB_PANIC("(value.kind=%s) %s vs %s",
+				         exact_value_kind_string[value.kind],
+				         temp_canonical_string(value_type), temp_canonical_string(original_type));
 			}
+		// union_multiple_allow_compound:;
 
 			lbValue cv = lb_const_value(m, value_type, value, value_type, cc);
 			Type *variant_type = cv.type;