mirror of
https://github.com/golang/go
synced 2024-11-02 13:42:29 +00:00
be1a693477
Includes Robert's suggested fix in validate.go to not fail on non-constant alignof/offsetof/sizeof calls. Further changes to wait on transforming these calls until stenciling time, when we can call EvalConst() to evaluate them once all the relevant types are known. Added a bunch of new tests for non-constant Sizeof/Alignof/Offsetof. Fixes #47716 Change-Id: I469af888eb9ce3a853124d919eda753971009b3e Reviewed-on: https://go-review.googlesource.com/c/go/+/344250 Run-TryBot: Dan Scales <danscales@google.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org> Trust: Dan Scales <danscales@google.com>
68 lines
1.6 KiB
Go
68 lines
1.6 KiB
Go
// run -gcflags=-G=3
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// Copyright 2021 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package main
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import (
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"fmt"
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"unsafe"
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)
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// size returns the size of type T
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func size[T any](x T) uintptr {
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return unsafe.Sizeof(x)
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}
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// size returns the alignment of type T
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func align[T any](x T) uintptr {
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return unsafe.Alignof(x)
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}
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type Tstruct[T any] struct {
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f1 T
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f2 int
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}
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// offset returns the offset of field f2 in the generic type Tstruct
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func (r *Tstruct[T]) offset() uintptr {
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return unsafe.Offsetof(r.f2)
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}
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func main() {
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v1 := int(5)
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if got, want := size(v1), unsafe.Sizeof(v1); got != want {
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panic(fmt.Sprintf("got %d, want %d", got, want))
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}
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if got, want := align(v1), unsafe.Alignof(v1); got != want {
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panic(fmt.Sprintf("got %d, want %d", got, want))
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}
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v2 := "abc"
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if got, want := size(v2), unsafe.Sizeof(v2); got != want {
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panic(fmt.Sprintf("got %d, want %d", got, want))
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}
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if got, want := align(v2), unsafe.Alignof(v2); got != want {
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panic(fmt.Sprintf("got %d, want %d", got, want))
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}
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var v3 Tstruct[int]
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if got, want := unsafe.Offsetof(v3.f2), unsafe.Sizeof(v1); got != want {
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panic(fmt.Sprintf("got %d, want %d", got, want))
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}
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var v4 Tstruct[interface{}]
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var v5 interface{}
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if got, want := unsafe.Offsetof(v4.f2), unsafe.Sizeof(v5); got != want {
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panic(fmt.Sprintf("got %d, want %d", got, want))
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}
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if got, want := v3.offset(), unsafe.Offsetof(v3.f2); got != want {
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panic(fmt.Sprintf("got %d, want %d", got, want))
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}
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if got, want := v4.offset(), unsafe.Offsetof(v4.f2); got != want {
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panic(fmt.Sprintf("got %d, want %d", got, want))
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}
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}
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