issue77779.go

     1  // run
     2  
     3  // Copyright 2026 The Go Authors. All rights reserved.
     4  // Use of this source code is governed by a BSD-style
     5  // license that can be found in the LICENSE file.
     6  
     7  package main
     8  
     9  import (
    10  	"reflect"
    11  )
    12  
    13  type Renderer interface {
    14  	Render() error
    15  }
    16  
    17  type ZeroSize struct{}
    18  
    19  func (ZeroSize) Render() error { return nil }
    20  
    21  type Data struct {
    22  	X, Y, Z int
    23  }
    24  
    25  // Container is pointer-sized (8 bytes): zero-size embed + one pointer field.
    26  // This triggers Go 1.26 interface inlining, which produces a nil data pointer
    27  // for the zero-size field when extracted via reflect.Value.Interface().
    28  type Container struct {
    29  	ZeroSize
    30  	Data *Data
    31  }
    32  
    33  func main() {
    34  	render(Container{})
    35  	render(&Container{})
    36  }
    37  
    38  func render(iface any) {
    39  	if reflect.ValueOf(iface).Kind() == reflect.Ptr {
    40  		_ = reflect.ValueOf(iface).Elem().Field(0).Interface().(Renderer).Render()
    41  		return
    42  	}
    43  
    44  	_ = reflect.ValueOf(iface).Field(0).Interface().(Renderer).Render()
    45  }
    46
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