gen: fix printing of generic arrays

vlib/v/checker/checker.v

@@ -1084,9 +1084,16 @@ pub fn (mut c Checker) call_fn(mut call_expr ast.CallExpr) table.Type {
 	}
 	if call_expr.generic_type != table.void_type && f.return_type != 0 { // table.t_type {
 		// Handle `foo<T>() T` => `foo<int>() int` => return int
-		sym := c.table.get_type_symbol(f.return_type)
-		if sym.name == 'T' {
+		return_sym := c.table.get_type_symbol(f.return_type)
+		if return_sym.name == 'T' {
 			return call_expr.generic_type
+		} else if return_sym.kind == .array {
+			elem_info := return_sym.info as table.Array
+			elem_sym := c.table.get_type_symbol(elem_info.elem_type)
+			if elem_sym.name == 'T' {
+				idx := c.table.find_or_register_array(call_expr.generic_type, 1, return_sym.mod)
+				return table.new_type(idx)
+			}
 		}
 	}
 	return f.return_type

vlib/v/gen/fn.v

@@ -77,9 +77,12 @@ fn (mut g Gen) gen_fn_decl(it ast.FnDecl) {
 		} else {
 			name = c_name(name)
 		}
+		mut type_name := g.typ(it.return_type)
 		if g.cur_generic_type != 0 {
 			// foo<T>() => foo_int(), foo_string() etc
-			name += '_' + g.typ(g.cur_generic_type)
+			gen_name := g.typ(g.cur_generic_type)
+			name += '_' + gen_name
+			type_name = type_name.replace('T', gen_name)
 		}
 		// if g.pref.show_cc && it.is_builtin {
 		// println(name)
@@ -96,7 +99,6 @@ fn (mut g Gen) gen_fn_decl(it ast.FnDecl) {
 		}
 		mut impl_fn_name := if is_live_wrap { 'impl_live_${name}' } else { name }
 		g.last_fn_c_name = impl_fn_name
-		type_name := g.typ(it.return_type)
 		//
 		if is_live_wrap {
 			if is_livemain {
@@ -248,6 +250,11 @@ fn (mut g Gen) fn_args(args []table.Arg, is_variadic bool) ([]string, []string)
 		// if arg.name == 'xxx' {
 		// println('xxx arg type= ' + arg_type_name)
 		// }
+		if g.cur_generic_type != 0 {
+			// foo<T>() => foo_int(), foo_string() etc
+			gen_name := g.typ(g.cur_generic_type)
+			arg_type_name = arg_type_name.replace('T', gen_name)
+		}
 		is_varg := i == args.len - 1 && is_variadic
 		if is_varg {
 			varg_type_str := int(arg.typ).str()

vlib/v/tests/generics_test.v

@@ -82,6 +82,21 @@ fn test_create() {
 	mut_arg2<User>(mut u)
 }
 
+fn return_array<T>(arr []T) []T {
+	return arr
+}
+
+fn test_return_array() {
+	a1 := return_array<int>([1, 2, 3])
+	assert a1 == [1, 2, 3]
+	a2 := return_array<f64>([1.1, 2.2, 3.3])
+	assert a2 == [1.1, 2.2, 3.3]
+	a3 := return_array<string>(['a', 'b', 'c'])
+	assert a3 == ['a', 'b', 'c']
+	a4 := return_array<bool>([true, false, true])
+	assert a4 == [true, false, true]
+}
+
 /*
 fn map_f<T,U>(l []T, f fn(T)U) []U {
     mut r := []U{}