From 59933b244ded0ab2476535b18875de95cd9f47bc Mon Sep 17 00:00:00 2001
From: gingerBill <bill@gingerbill.org>
Date: Thu, 8 Feb 2024 13:41:02 +0000
Subject: [PATCH] Allow polymorphic checking with
 `intrinsics.type_is_subtype_of(Derived_Type, Poly_Type)`

---
 src/check_builtin.cpp |  2 +-
 src/check_type.cpp    | 14 ++++++++++++--
 src/types.cpp         | 19 +++++++++++++++++--
 3 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/src/check_builtin.cpp b/src/check_builtin.cpp
index e1cb43ec1..4e374add6 100644
--- a/src/check_builtin.cpp
+++ b/src/check_builtin.cpp
@@ -5686,7 +5686,7 @@ gb_internal bool check_builtin_procedure(CheckerContext *c, Operand *operand, As
 				return false;
 			}
 
-			operand->value = exact_value_bool(is_type_subtype_of(op_src.type, op_dst.type));
+			operand->value = exact_value_bool(is_type_subtype_of_and_allow_polymorphic(op_src.type, op_dst.type));
 			operand->mode = Addressing_Constant;
 			operand->type = t_untyped_bool;
 		} break;
diff --git a/src/check_type.cpp b/src/check_type.cpp
index 4d0901605..15bba5319 100644
--- a/src/check_type.cpp
+++ b/src/check_type.cpp
@@ -1,5 +1,6 @@
 gb_internal ParameterValue handle_parameter_value(CheckerContext *ctx, Type *in_type, Type **out_type_, Ast *expr, bool allow_caller_location);
 gb_internal Type *determine_type_from_polymorphic(CheckerContext *ctx, Type *poly_type, Operand const &operand);
+gb_internal Type *check_get_params(CheckerContext *ctx, Scope *scope, Ast *_params, bool *is_variadic_, isize *variadic_index_, bool *success_, isize *specialization_count_, Array<Operand> const *operands);
 
 gb_internal void populate_using_array_index(CheckerContext *ctx, Ast *node, AstField *field, Type *t, String name, i32 idx) {
 	t = base_type(t);
@@ -394,7 +395,6 @@ gb_internal Type *check_record_polymorphic_params(CheckerContext *ctx, Ast *poly
                                                   bool *is_polymorphic_,
                                                   Ast *node, Array<Operand> *poly_operands) {
 	Type *polymorphic_params_type = nullptr;
-	bool can_check_fields = true;
 	GB_ASSERT(is_polymorphic_ != nullptr);
 
 	if (polymorphic_params == nullptr) {
@@ -404,6 +404,17 @@ gb_internal Type *check_record_polymorphic_params(CheckerContext *ctx, Ast *poly
 		return polymorphic_params_type;
 	}
 
+
+	// bool is_variadic = false;
+	// isize variadic_index = 0;
+	// bool success = false;
+	// isize specialization_count = 0;
+	// polymorphic_params_type = check_get_params(ctx, ctx->scope, polymorphic_params, &is_variadic, &variadic_index, &success, &specialization_count, poly_operands);
+	// if (success) {
+	// 	return nullptr;
+	// }
+
+	bool can_check_fields = true;
 	ast_node(field_list, FieldList, polymorphic_params);
 	Slice<Ast *> params = field_list->list;
 	if (params.count != 0) {
@@ -565,7 +576,6 @@ gb_internal Type *check_record_polymorphic_params(CheckerContext *ctx, Ast *poly
 	if (!*is_polymorphic_) {
 		*is_polymorphic_ = polymorphic_params != nullptr && poly_operands == nullptr;
 	}
-
 	return polymorphic_params_type;
 }
 
diff --git a/src/types.cpp b/src/types.cpp
index b99d469e4..c4b03c967 100644
--- a/src/types.cpp
+++ b/src/types.cpp
@@ -4093,7 +4093,7 @@ gb_internal i64 type_offset_of_from_selection(Type *type, Selection sel) {
 	return offset;
 }
 
-gb_internal isize check_is_assignable_to_using_subtype(Type *src, Type *dst, isize level = 0, bool src_is_ptr = false) {
+gb_internal isize check_is_assignable_to_using_subtype(Type *src, Type *dst, isize level = 0, bool src_is_ptr = false, bool allow_polymorphic=false) {
 	Type *prev_src = src;
 	src = type_deref(src);
 	if (!src_is_ptr) {
@@ -4105,11 +4105,19 @@ gb_internal isize check_is_assignable_to_using_subtype(Type *src, Type *dst, isi
 		return 0;
 	}
 
+	bool dst_is_polymorphic = is_type_polymorphic(dst);
+
 	for_array(i, src->Struct.fields) {
 		Entity *f = src->Struct.fields[i];
 		if (f->kind != Entity_Variable || (f->flags&EntityFlags_IsSubtype) == 0) {
 			continue;
 		}
+		if (allow_polymorphic && dst_is_polymorphic) {
+			Type *fb = base_type(type_deref(f->type));
+			if (fb->kind == Type_Struct && fb->Struct.polymorphic_parent == dst) {
+				return true;
+			}
+		}
 
 		if (are_types_identical(f->type, dst)) {
 			return level+1;
@@ -4119,7 +4127,7 @@ gb_internal isize check_is_assignable_to_using_subtype(Type *src, Type *dst, isi
 				return level+1;
 			}
 		}
-		isize nested_level = check_is_assignable_to_using_subtype(f->type, dst, level+1, src_is_ptr);
+		isize nested_level = check_is_assignable_to_using_subtype(f->type, dst, level+1, src_is_ptr, allow_polymorphic);
 		if (nested_level > 0) {
 			return nested_level;
 		}
@@ -4135,6 +4143,13 @@ gb_internal bool is_type_subtype_of(Type *src, Type *dst) {
 
 	return 0 < check_is_assignable_to_using_subtype(src, dst, 0, is_type_pointer(src));
 }
+gb_internal bool is_type_subtype_of_and_allow_polymorphic(Type *src, Type *dst) {
+	if (are_types_identical(src, dst)) {
+		return true;
+	}
+
+	return 0 < check_is_assignable_to_using_subtype(src, dst, 0, is_type_pointer(src), true);
+}
 
 
 gb_internal bool has_type_got_objc_class_attribute(Type *t) {