cgen: fix code generation for generic channels (#19993)

vlib/v/ast/table.v

@@ -922,7 +922,12 @@ pub fn (t &Table) chan_cname(elem_type Type, is_mut bool) string {
 	} else if elem_type.is_ptr() {
 		suffix = '_ptr'
 	}
-	return 'chan_${elem_type_sym.cname}' + suffix
+	type_name := if elem_type_sym.cname.contains('[') {
+		elem_type_sym.cname.replace_each(ast.map_cname_escape_seq)
+	} else {
+		elem_type_sym.cname
+	}
+	return 'chan_${type_name}' + suffix
 }
 
 @[inline]

vlib/v/tests/chan_generic_test.v

@@ -0,0 +1,16 @@
+struct Task[T] {
+	idx  int
+	task T
+}
+
+fn check[T](input T) T {
+	ch := chan Task[T]{}
+	// do something with channel
+	ch.close()
+	return input
+}
+
+fn test_main() {
+	out := check[int](5)
+	assert out == 5
+}