cgen: fix generic with multi-nested generic method call ref argument (#15421)

vlib/v/gen/c/cgen.v

@@ -2247,8 +2247,7 @@ fn (mut g Gen) expr_with_cast(expr ast.Expr, got_type_raw ast.Type, expected_typ
 		deref_sym := g.table.sym(got_deref_type)
 		deref_will_match := expected_type in [got_type, got_deref_type, deref_sym.parent_idx]
 		got_is_opt := got_type.has_flag(.optional)
-		if deref_will_match || got_is_opt || expr.is_auto_deref_var()
-			|| expected_type.has_flag(.generic) {
+		if deref_will_match || got_is_opt || expr.is_auto_deref_var() {
 			g.write('*')
 		}
 	}

vlib/v/gen/c/fn.v

@@ -980,7 +980,8 @@ fn (mut g Gen) method_call(node ast.CallExpr) {
 			}
 		}
 	}
-	name = g.generic_fn_name(node.concrete_types, name, false)
+	concrete_types := node.concrete_types.map(g.unwrap_generic(it))
+	name = g.generic_fn_name(concrete_types, name, false)
 	// TODO2
 	// g.generate_tmp_autofree_arg_vars(node, name)
 	if !node.receiver_type.is_ptr() && left_type.is_ptr() && node.name == 'str' {

vlib/v/tests/generics_with_multi_nested_generic_method_call_ref_arg_test.v

@@ -0,0 +1,109 @@
+struct Wrapper<S> {
+mut:
+	calc Calc<S>
+}
+
+fn (mut w Wrapper<S>) next<T>(input T) f64 {
+	$if S is TypeA || S is TypeB {
+		$if T is f64 {
+			return w.calc.next(input)
+		} $else $if T is SecretCase {
+			return w.calc.next(input)
+		} $else {
+			panic('"$T.name" is not supported')
+			return -1
+		}
+		return -1
+	} $else {
+		panic('"$S.name" is not supported')
+		return -1
+	}
+}
+
+struct Calc<S> {
+mut:
+	typ   S
+	inner InnerCalc
+}
+
+struct InnerCalc {}
+
+fn (mut c InnerCalc) next<T>(input T) f64 {
+	$if T is f64 {
+		return 64.2
+	} $else {
+		return 100.0
+	}
+}
+
+struct TypeA {}
+
+struct TypeB {}
+
+interface SecretCase {
+	secret() f64
+}
+
+interface SpecialCase {
+	SecretCase
+}
+
+struct SecretSkill {}
+
+fn (s &SecretSkill) secret() f64 {
+	return 101.0
+}
+
+fn (mut c Calc<S>) next<T>(input T) f64 {
+	$if S is TypeA || S is TypeB {
+		$if T is f64 {
+			return c.typ.next(input)
+		} $else $if T is SpecialCase {
+			return c.typ.next(input)
+		} $else {
+			panic('Unsupported type $T.name')
+		}
+	} $else {
+		panic('Unsupported type $S.name')
+	}
+}
+
+fn (mut t TypeA) next<T>(input T) f64 {
+	return 10
+}
+
+fn (mut t TypeB) next<T>(input T) f64 {
+	return 11
+}
+
+fn new<S>() Wrapper<S> {
+	$if S is TypeA {
+		return Wrapper<TypeA>{
+			calc: Calc<TypeA>{
+				typ: TypeA{}
+			}
+		}
+	} $else $if S is TypeB {
+		return Wrapper<TypeB>{
+			calc: Calc<TypeB>{
+				typ: TypeB{}
+			}
+		}
+	} $else {
+		panic('unknown type $S.name')
+	}
+}
+
+fn test_generics_with_multi_nested_generic_method_call_ref_arg() {
+	{
+		mut c := new<TypeA>()
+		s := SecretSkill{}
+		assert c.next(&s) == 10.0
+	}
+	{
+		mut c := new<TypeB>()
+		s := SecretSkill{}
+		assert c.next(&s) == 11.0
+	}
+	println('OK!!')
+}