diff options
| -rw-r--r-- | src/pkg/runtime/iface.goc | 23 | ||||
| -rw-r--r-- | test/fixedbugs/issue8139.go | 50 |
2 files changed, 69 insertions, 4 deletions
diff --git a/src/pkg/runtime/iface.goc b/src/pkg/runtime/iface.goc index 96bb8b8aa..c0a17e303 100644 --- a/src/pkg/runtime/iface.goc +++ b/src/pkg/runtime/iface.goc @@ -209,9 +209,19 @@ func convT2E(t *Type, elem *byte) (ret Eface) { static void assertI2Tret(Type *t, Iface i, byte *ret); +/* + * NOTE: Cannot use 'func' here, because we have to declare + * a return value, the only types we have are at least 1 byte large, + * goc2c will zero the return value, and the actual return value + * might have size 0 bytes, in which case the zeroing of the + * 1 or more bytes would be wrong. + * Using C lets us control (avoid) the initial zeroing. + */ #pragma textflag NOSPLIT -func assertI2T(t *Type, i Iface) (ret byte, ...) { - assertI2Tret(t, i, &ret); +void +runtime·assertI2T(Type *t, Iface i, GoOutput retbase) +{ + assertI2Tret(t, i, (byte*)&retbase); } static void @@ -260,9 +270,14 @@ func assertI2TOK(t *Type, i Iface) (ok bool) { static void assertE2Tret(Type *t, Eface e, byte *ret); +/* + * NOTE: Cannot use 'func' here. See assertI2T above. + */ #pragma textflag NOSPLIT -func assertE2T(t *Type, e Eface) (ret byte, ...) { - assertE2Tret(t, e, &ret); +void +runtime·assertE2T(Type *t, Eface e, GoOutput retbase) +{ + assertE2Tret(t, e, (byte*)&retbase); } static void diff --git a/test/fixedbugs/issue8139.go b/test/fixedbugs/issue8139.go new file mode 100644 index 000000000..821c9ff65 --- /dev/null +++ b/test/fixedbugs/issue8139.go @@ -0,0 +1,50 @@ +// run + +// Copyright 2014 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// Issue 8139. The x.(T) assertions used to write 1 (unexpected) +// return byte for the 0-byte return value T. + +package main + +import "fmt" + +type T struct{} + +func (T) M() {} + +type M interface { + M() +} + +var e interface{} = T{} +var i M = T{} +var b bool + +func f1() int { + if b { + return f1() // convince inliner not to inline + } + z := 0x11223344 + _ = e.(T) + return z +} + +func f2() int { + if b { + return f1() // convince inliner not to inline + } + z := 0x11223344 + _ = i.(T) + return z +} + +func main() { + x := f1() + y := f2() + if x != 0x11223344 || y != 0x11223344 { + fmt.Printf("BUG: x=%#x y=%#x, want 0x11223344 for both\n", x, y) + } +} |