From c1e8612624be5d73cb516775958ab89d3dae0ae0 Mon Sep 17 00:00:00 2001
From: joe-conigliaro <joe.conigliaro@gmail.com>
Date: Wed, 22 Apr 2020 13:28:47 +1000
Subject: [PATCH] checker/gen: allow vargs to be forwarded. fix/enable variadic
 test

---
 cmd/tools/vtest-fixed.v  | 1 -
 vlib/v/checker/checker.v | 9 ++++++++-
 vlib/v/gen/fn.v          | 8 +++++---
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/cmd/tools/vtest-fixed.v b/cmd/tools/vtest-fixed.v
index fb2a054569..e0b8501036 100644
--- a/cmd/tools/vtest-fixed.v
+++ b/cmd/tools/vtest-fixed.v
@@ -18,7 +18,6 @@ const (
 		'vlib/regex/regex_test.v',
 		'vlib/v/tests/enum_bitfield_test.v',
 		'vlib/v/tests/fixed_array_test.v',
-		'vlib/v/tests/fn_variadic_test.v',
 		'vlib/v/tests/num_lit_call_method_test.v',
 		'vlib/v/tests/option_test.v',
 		'vlib/v/tests/pointers_test.v',
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index f5ae37c9d4..50868862a6 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -492,7 +492,11 @@ pub fn (c mut Checker) call_method(call_expr mut ast.CallExpr) table.Type {
 			} else {
 				method.args[i + 1].typ
 			}
-			call_expr.args[i].typ = c.expr(arg.expr)
+			arg_typ := c.expr(arg.expr)
+			call_expr.args[i].typ = arg_typ
+			if method.is_variadic && table.type_is(arg_typ, .variadic) && call_expr.args.len-1 > i  {
+				c.error('when forwarding a varg variable, it must be the final argument', call_expr.pos)
+			}
 		}
 		// TODO: typ optimize.. this node can get processed more than once
 		if call_expr.expected_arg_types.len == 0 {
@@ -616,6 +620,9 @@ pub fn (c mut Checker) call_fn(call_expr mut ast.CallExpr) table.Type {
 		call_expr.args[i].typ = typ
 		typ_sym := c.table.get_type_symbol(typ)
 		arg_typ_sym := c.table.get_type_symbol(arg.typ)
+		if f.is_variadic && table.type_is(typ, .variadic) && call_expr.args.len-1 > i {
+			c.error('when forwarding a varg variable, it must be the final argument', call_expr.pos)
+		}
 		if !c.table.check(typ, arg.typ) {
 			// str method, allow type with str method if fn arg is string
 			if arg_typ_sym.kind == .string && typ_sym.has_method('str') {
diff --git a/vlib/v/gen/fn.v b/vlib/v/gen/fn.v
index c399e4070a..0399546745 100644
--- a/vlib/v/gen/fn.v
+++ b/vlib/v/gen/fn.v
@@ -384,9 +384,11 @@ fn (g mut Gen) fn_call(node ast.CallExpr) {
 fn (g mut Gen) call_args(args []ast.CallArg, expected_types []table.Type) {
 	is_variadic := expected_types.len > 0 && table.type_is(expected_types[expected_types.len -
 		1], .variadic)
+	is_forwarding_varg := args.len > 0 && table.type_is(args[args.len-1].typ, .variadic)
+	gen_vargs := is_variadic && !is_forwarding_varg
 	mut arg_no := 0
 	for arg in args {
-		if is_variadic && arg_no == expected_types.len - 1 {
+		if gen_vargs && arg_no == expected_types.len - 1 {
 			break
 		}
 		// some c fn definitions dont have args (cfns.v) or are not updated in checker
@@ -396,12 +398,12 @@ fn (g mut Gen) call_args(args []ast.CallArg, expected_types []table.Type) {
 		} else {
 			g.expr(arg.expr)
 		}
-		if arg_no < args.len - 1 || is_variadic {
+		if arg_no < args.len - 1 || gen_vargs {
 			g.write(', ')
 		}
 		arg_no++
 	}
-	if is_variadic {
+	if is_variadic && !is_forwarding_varg {
 		varg_type := expected_types[expected_types.len - 1]
 		struct_name := 'varg_' + g.typ(varg_type).replace('*', '_ptr')
 		variadic_count := args.len - arg_no