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go/test/typeparam/issue54535.go
Matthew Dempsky 6985ab27df cmd/compile: fix unified IR's pointer-shaping
In CL 424734, I implemented pointer shaping for unified IR. Evidently
though, we didn't have any test cases that check that uses of
pointer-shaped expressions were handled correctly.

In the reported test case, the struct field "children items[*node[T]]"
gets shaped to "children items[go.shape.*uint8]" (underlying type
"[]go.shape.*uint8"); and so the expression "n.children[i]" has type
"go.shape.*uint8" and the ".items" field selection expression fails.

The fix implemented in this CL is that any expression of derived type
now gets an explicit "reshape" operation applied to it, to ensure it
has the appropriate type for its context. E.g., the "n.children[i]"
OINDEX expression above gets "reshaped" from "go.shape.*uint8" to
"*node[go.shape.int]", allowing the field selection to succeed.

This CL also adds a "-d=reshape" compiler debugging flag, because I
anticipate debugging reshaping operations will be something to come up
again in the future.

Fixes #54535.

Change-Id: Id847bd8f51300d2491d679505ee4d2e974ca972a
Reviewed-on: https://go-review.googlesource.com/c/go/+/424936
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: hopehook <hopehook@qq.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
2022-08-23 18:14:10 +00:00

38 lines
559 B
Go

// run
// Copyright 2022 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
type node[T any] struct {
items items[T]
children items[*node[T]]
}
func (n *node[T]) f(i int, j int) bool {
if len(n.children[i].items) < j {
return false
}
return true
}
type items[T any] []T
func main() {
_ = node[int]{}
_ = f[int]
}
type s[T, U any] struct {
a T
c U
}
func f[T any]() {
var x s[*struct{ b T }, *struct{ d int }]
_ = x.a.b
_ = x.c.d
}