compiler: fix variadic args not being nil when zero length.

Author: myitcv

compiler/utils.go

@@ -95,6 +95,10 @@ func (c *funcContext) translateArgs(sig *types.Signature, argExprs []ast.Expr, e
 		varargType = sig.Params().At(paramsLen - 1).Type().(*types.Slice)
 	}
 
+	if sig.Variadic() && len(argExprs) == 0 {
+		return []string{fmt.Sprintf("%s.nil", c.typeName(varargType))}
+	}
+
 	preserveOrder := false
 	for i := 1; i < len(argExprs); i++ {
 		preserveOrder = preserveOrder || c.Blocking[argExprs[i]]

tests/compiler_test.go

@@ -0,0 +1,29 @@
+package tests
+
+import (
+	"testing"
+)
+
+func TestVariadicNil(t *testing.T) {
+	printVari := func(strs ...string) []string {
+		return strs
+	}
+
+	if got := printVari(); got != nil {
+		t.Errorf("printVari(): got: %#v; want %#v.", got, nil)
+	}
+
+	{
+		var want []string
+		if got := printVari(want...); got != nil {
+			t.Errorf("printVari(want...): got: %#v; want %#v.", got, nil)
+		}
+	}
+
+	{
+		want := []string{}
+		if got := printVari(want...); got == nil || len(got) != len(want) {
+			t.Errorf("printVari(want...): got: %#v; want %#v.", got, want)
+		}
+	}
+}