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// run -gcflags=-G=3
// Copyright 2021 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 (
"fmt"
"unsafe"
)
// size returns the size of type T
func size[T any](x T) uintptr {
return unsafe.Sizeof(x)
}
// size returns the alignment of type T
func align[T any](x T) uintptr {
return unsafe.Alignof(x)
}
type Tstruct[T any] struct {
f1 T
f2 int
}
// offset returns the offset of field f2 in the generic type Tstruct
func (r *Tstruct[T]) offset() uintptr {
return unsafe.Offsetof(r.f2)
}
func main() {
v1 := int(5)
if got, want := size(v1), unsafe.Sizeof(v1); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
if got, want := align(v1), unsafe.Alignof(v1); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
v2 := "abc"
if got, want := size(v2), unsafe.Sizeof(v2); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
if got, want := align(v2), unsafe.Alignof(v2); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
var v3 Tstruct[int]
if got, want := unsafe.Offsetof(v3.f2), unsafe.Sizeof(v1); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
var v4 Tstruct[interface{}]
var v5 interface{}
if got, want := unsafe.Offsetof(v4.f2), unsafe.Sizeof(v5); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
if got, want := v3.offset(), unsafe.Offsetof(v3.f2); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
if got, want := v4.offset(), unsafe.Offsetof(v4.f2); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
}
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