diff options
| -rw-r--r-- | src/reflect/value.go | 5 | ||||
| -rw-r--r-- | test/fixedbugs/issue77779.go | 45 |
2 files changed, 48 insertions, 2 deletions
diff --git a/src/reflect/value.go b/src/reflect/value.go index 8c8acbaa9a..f192eb5974 100644 --- a/src/reflect/value.go +++ b/src/reflect/value.go @@ -1288,9 +1288,10 @@ func (v Value) Field(i int) Value { // bunch of zero-sized fields. We must return the zero-sized // fields indirectly, as only ptr-shaped things can be direct. // See issue 74935. - // We use nil instead of v.ptr as it doesn't matter and + // We use &zeroVal[0] instead of v.ptr as it doesn't matter and // we can avoid pinning a possibly now-unused object. - return Value{typ, nil, fl | flagIndir} + // Don't use nil, see issue 77779. + return Value{typ, unsafe.Pointer(&zeroVal[0]), fl | flagIndir} } // Either flagIndir is set and v.ptr points at struct, diff --git a/test/fixedbugs/issue77779.go b/test/fixedbugs/issue77779.go new file mode 100644 index 0000000000..1a61b2cbe0 --- /dev/null +++ b/test/fixedbugs/issue77779.go @@ -0,0 +1,45 @@ +// run + +// Copyright 2026 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. + +package main + +import ( + "reflect" +) + +type Renderer interface { + Render() error +} + +type ZeroSize struct{} + +func (ZeroSize) Render() error { return nil } + +type Data struct { + X, Y, Z int +} + +// Container is pointer-sized (8 bytes): zero-size embed + one pointer field. +// This triggers Go 1.26 interface inlining, which produces a nil data pointer +// for the zero-size field when extracted via reflect.Value.Interface(). +type Container struct { + ZeroSize + Data *Data +} + +func main() { + render(Container{}) + render(&Container{}) +} + +func render(iface any) { + if reflect.ValueOf(iface).Kind() == reflect.Ptr { + _ = reflect.ValueOf(iface).Elem().Field(0).Interface().(Renderer).Render() + return + } + + _ = reflect.ValueOf(iface).Field(0).Interface().(Renderer).Render() +} |
