Merge pull request #445 from brett19/master

neelance · neelance · commit 24a7ce52800b · 2016-05-01T22:12:48.000+02:00
perform implicit casting for tuple returns if needed (fixes #444)
diff --git a/compiler/statements.go b/compiler/statements.go
@@ -748,7 +748,26 @@ func (c *funcContext) translateResults(results []ast.Expr) string {
 		return " " + v.String()
 	default:
 		if len(results) == 1 {
-			return " " + c.translateExpr(results[0]).String()
+			resultTuple := c.p.TypeOf(results[0]).(*types.Tuple)
+
+			if resultTuple.Len() != tuple.Len() {
+				panic("invalid tuple return assignment")
+			}
+
+			resultExpr := c.translateExpr(results[0]).String()
+
+			if types.Identical(resultTuple, tuple) {
+				return " " + resultExpr
+			}
+
+			tmpVar := c.newVariable("_returncast")
+			c.Printf("%s = %s;", tmpVar, resultExpr)
+
+			// Not all the return types matched, map everything out for implicit casting
+			results = make([]ast.Expr, resultTuple.Len())
+			for i := range results {
+				results[i] = c.newIdent(fmt.Sprintf("%s[%d]", tmpVar, i), resultTuple.At(i).Type())
+			}
 		}
 		values := make([]string, tuple.Len())
 		for i := range values {
diff --git a/tests/misc_test.go b/tests/misc_test.go
@@ -535,3 +535,53 @@ func TestTrivialSwitch(t *testing.T) {
 	}
 	t.Fail()
 }
+
+func TestTupleFnReturnImplicitCast(t *testing.T) {
+	var ycalled int = 0
+	x := func(fn func() (int, error)) (interface{}, error) {
+		return fn()
+	}
+	y, _ := x(func() (int, error) {
+		ycalled++
+		return 14, nil
+	})
+	if y != 14 || ycalled != 1 {
+		t.Fail()
+	}
+}
+
+var tuple2called = 0
+
+func tuple1() (interface{}, error) {
+	return tuple2()
+}
+func tuple2() (int, error) {
+	tuple2called++
+	return 14, nil
+}
+func TestTupleReturnImplicitCast(t *testing.T) {
+	x, _ := tuple1()
+	if x != 14 || tuple2called != 1 {
+		t.Fail()
+	}
+}
+
+func TestDeferNamedTupleReturnImplicitCast(t *testing.T) {
+	var ycalled int = 0
+	var zcalled int = 0
+	z := func() {
+		zcalled++
+	}
+	x := func(fn func() (int, error)) (i interface{}, e error) {
+		defer z()
+		i, e = fn()
+		return
+	}
+	y, _ := x(func() (int, error) {
+		ycalled++
+		return 14, nil
+	})
+	if y != 14 || ycalled != 1 || zcalled != 1 {
+		t.Fail()
+	}
+}
