From 9a31744255057495d7c46bc332a027fab918eca5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20D=C3=A4schle?= <daniel.daeschle@gmail.com>
Date: Wed, 30 Dec 2020 23:49:02 +0100
Subject: [PATCH] cgen: fix embed generic field access & method call (#7725)

---
 vlib/v/checker/checker.v         |  7 +++++--
 vlib/v/gen/cgen.v                |  2 +-
 vlib/v/tests/struct_embed_test.v | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 9257b0939e..8418195ef4 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -1258,6 +1258,7 @@ pub fn (mut c Checker) call_method(mut call_expr ast.CallExpr) table.Type {
 	}
 	mut method := table.Fn{}
 	mut has_method := false
+	mut is_method_from_embed := false
 	if m := c.table.type_find_method(left_type_sym, method_name) {
 		method = m
 		has_method = true
@@ -1275,6 +1276,7 @@ pub fn (mut c Checker) call_method(mut call_expr ast.CallExpr) table.Type {
 			if found_methods.len == 1 {
 				method = found_methods[0]
 				has_method = true
+				is_method_from_embed = true
 				call_expr.from_embed_type = embed_of_found_methods[0]
 			} else if found_methods.len > 1 {
 				c.error('ambiguous method `$method_name`', call_expr.pos)
@@ -1374,12 +1376,13 @@ pub fn (mut c Checker) call_method(mut call_expr ast.CallExpr) table.Type {
 				call_expr.expected_arg_types << method.params[i].typ
 			}
 		}
-		if is_generic {
+		if is_method_from_embed {
+			call_expr.receiver_type = call_expr.from_embed_type.derive(method.params[0].typ)
+		} else if is_generic {
 			// We need the receiver to be T in cgen.
 			// TODO: cant we just set all these to the concrete type in checker? then no need in gen
 			call_expr.receiver_type = left_type.derive(method.params[0].typ).set_flag(.generic)
 		} else {
-			// note: correct receiver type is automatically set here on struct embed calls
 			call_expr.receiver_type = method.params[0].typ
 		}
 		call_expr.return_type = method.return_type
diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index 892fd531c2..dd7e6573dc 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -2768,7 +2768,7 @@ fn (mut g Gen) selector_expr(node ast.SelectorExpr) {
 	if node.expr_type == 0 {
 		g.checker_bug('unexpected SelectorExpr.expr_type = 0', node.pos)
 	}
-	sym := g.table.get_type_symbol(node.expr_type)
+	sym := g.table.get_type_symbol(g.unwrap_generic(node.expr_type))
 	// if node expr is a root ident and an optional
 	mut is_optional := node.expr is ast.Ident && node.expr_type.has_flag(.optional)
 	if is_optional {
diff --git a/vlib/v/tests/struct_embed_test.v b/vlib/v/tests/struct_embed_test.v
index ac0165165f..44892d4bb5 100644
--- a/vlib/v/tests/struct_embed_test.v
+++ b/vlib/v/tests/struct_embed_test.v
@@ -116,3 +116,35 @@ fn test_embed_mutable() {
 	mut a := field_publicity.App{}
 	a.Context = field_publicity.Context{}
 }
+
+struct Context {
+	static_files string
+}
+
+fn (c Context) test() bool {
+	return true
+}
+
+struct App {
+	Context
+}
+
+fn embed_field_access_generic<T>(mut app T) {
+	app.Context = Context{
+		static_files: app.static_files
+	}
+}
+
+fn test_embed_field_access_generic() {
+	mut app := App{}
+	embed_field_access_generic(mut app)
+}
+
+fn embed_method_generic<T>(app T) bool {
+	return app.test()
+}
+
+fn test_embed_method_generic() {
+	mut app := App{}
+	assert embed_method_generic(app)
+}