From 04ff511e27cf5af69a851a9345412f190c59ad1b Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Wed, 10 Jul 2024 06:42:08 -0300
Subject: [PATCH] cgen, checker: fix wrong receiver generic resolution with
 embed types (#21833)

---
 vlib/v/checker/fn.v                        |  10 ++-
 vlib/v/gen/c/fn.v                          |  13 ++-
 vlib/v/tests/generic_receiver_embed_test.v | 100 +++++++++++++++++++++
 3 files changed, 120 insertions(+), 3 deletions(-)
 create mode 100644 vlib/v/tests/generic_receiver_embed_test.v

diff --git a/vlib/v/checker/fn.v b/vlib/v/checker/fn.v
index 60241a3218..03d91353d1 100644
--- a/vlib/v/checker/fn.v
+++ b/vlib/v/checker/fn.v
@@ -1589,15 +1589,23 @@ fn (mut c Checker) register_trace_call(node ast.CallExpr, func ast.Fn) {
 fn (mut c Checker) is_generic_expr(node ast.Expr) bool {
 	return match node {
 		ast.Ident {
+			// variable declared as generic type
 			c.comptime.is_generic_param_var(node)
 		}
 		ast.IndexExpr {
+			// generic_var[N]
 			c.comptime.is_generic_param_var(node.left)
 		}
 		ast.CallExpr {
-			node.args.any(c.comptime.is_generic_param_var(it.expr))
+			// fn which has any generic dependent expr
+			if node.args.any(c.comptime.is_generic_param_var(it.expr)) {
+				return true
+			}
+			// fn[T]() or generic_var.fn[T]()
+			node.concrete_types.any(it.has_flag(.generic))
 		}
 		ast.SelectorExpr {
+			// generic_var.property
 			c.comptime.is_generic_param_var(node.expr)
 		}
 		else {
diff --git a/vlib/v/gen/c/fn.v b/vlib/v/gen/c/fn.v
index 352ec4d86a..a579375b11 100644
--- a/vlib/v/gen/c/fn.v
+++ b/vlib/v/gen/c/fn.v
@@ -1804,13 +1804,22 @@ fn (mut g Gen) method_call(node ast.CallExpr) {
 			g.expr(node.left)
 		}
 		if !is_interface || node.from_embed_types.len == 0 {
-			for i, embed in node.from_embed_types {
+			mut node_embed_types := node.from_embed_types.clone()
+			if node.left is ast.Ident && g.comptime.get_ct_type_var(node.left) == .generic_var {
+				_, embed_types := g.table.find_method_from_embeds(final_left_sym, node.name) or {
+					ast.Fn{}, []ast.Type{}
+				}
+				if embed_types.len > 0 {
+					node_embed_types = embed_types.clone()
+				}
+			}
+			for i, embed in node_embed_types {
 				embed_sym := g.table.sym(embed)
 				embed_name := embed_sym.embed_name()
 				is_left_ptr := if i == 0 {
 					left_type.is_ptr()
 				} else {
-					node.from_embed_types[i - 1].is_ptr()
+					node_embed_types[i - 1].is_ptr()
 				}
 				if is_left_ptr {
 					g.write('->')
diff --git a/vlib/v/tests/generic_receiver_embed_test.v b/vlib/v/tests/generic_receiver_embed_test.v
new file mode 100644
index 0000000000..c3da9a260a
--- /dev/null
+++ b/vlib/v/tests/generic_receiver_embed_test.v
@@ -0,0 +1,100 @@
+pub type Entity = u64
+type ComponentType = u16
+
+pub struct Context {
+pub mut:
+	ecs &Ecs
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+pub struct EntityManager {
+mut:
+	living_entity_count u64
+}
+
+fn (mut self EntityManager) create_entity() Entity {
+	entity := self.living_entity_count
+	self.living_entity_count++
+	return entity
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+
+pub interface ISystem {
+	ecs &Ecs
+mut:
+	init()
+}
+
+pub struct System {
+pub mut:
+	ecs &Ecs
+}
+
+pub fn (mut self System) init() {
+}
+
+pub struct SystemManager {
+mut:
+	system_array map[string]ISystem = {}
+}
+
+fn (mut self SystemManager) add_system[T]() &T {
+	mut t := T{}
+	self.system_array[typeof[T]().name] = t
+	return &t
+}
+
+////////////////////////////////////////////////////////////////////////////
+
+@[heap]
+pub struct Ecs {
+mut:
+	entity_manager EntityManager
+	system_manager SystemManager
+pub mut:
+	root_entity Entity
+}
+
+pub fn Ecs.new() &Ecs {
+	mut ecs := &Ecs{}
+	ecs.root_entity = ecs.create_entity()
+	return ecs
+}
+
+pub fn (mut self Ecs) create_entity() Entity {
+	return self.entity_manager.create_entity()
+}
+
+pub fn (mut self Ecs) add_system[T]() {
+	mut system := self.system_manager.add_system[T]()
+	system.ecs = &self
+	system.init()
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct NetworkUdpServerComponent {
+}
+
+struct NetworkServerSystemUdp {
+	System
+}
+
+pub struct ConfigSystem {
+	System
+}
+
+struct NetworkServerSystemUdpExt {
+	NetworkServerSystemUdp
+}
+
+fn test_main() {
+	mut ecs := Ecs.new()
+	mut root_entity := ecs.create_entity()
+
+	ecs.add_system[ConfigSystem]()
+	ecs.add_system[NetworkServerSystemUdpExt]()
+
+	assert true
+}