types2, go/types: "cannot convert to type" regression with alias to pointer types

[mvdan]

Go version

go version devel go1.23-22344e11f2 2024-05-20 21:19:39 +0000 linux/amd64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/mvdan/.cache/go-build'
GOENV='/home/mvdan/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/mvdan/go/pkg/mod'
GONOPROXY='github.com/cue-unity'
GONOSUMDB='github.com/cue-unity'
GOOS='linux'
GOPATH='/home/mvdan/go'
GOPRIVATE='github.com/cue-unity'
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/mvdan/tip'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/mvdan/tip/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='devel go1.23-22344e11f2 2024-05-20 21:19:39 +0000'
GODEBUG=''
GOTELEMETRY='on'
GOTELEMETRYDIR='/home/mvdan/.config/go/telemetry'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/dev/null'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build3927267404=/tmp/go-build -gno-record-gcc-switches'

What did you do?

$ git clone https://github.com/ipld/go-codec-dagpb
$ cd go-codec-dagpb
$ go build

What did you see happen?

$ go version
go version devel go1.23-22344e11f2 2024-05-20 21:19:39 +0000 linux/amd64
$ go build
# github.com/ipld/go-codec-dagpb
./ipldsch_satisfaction.go:1164:26: cannot convert n (variable of type PBLink) to type *_PBLink__Repr
./ipldsch_satisfaction.go:2010:27: cannot convert n (variable of type PBLinks) to type *_PBLinks__Repr
./ipldsch_satisfaction.go:2024:22: cannot convert nr (variable of type *_PBLinks__Repr) to type PBLinks
./ipldsch_satisfaction.go:2031:22: cannot convert nr (variable of type *_PBLinks__Repr) to type PBLinks
./ipldsch_satisfaction.go:2048:42: cannot convert nr (variable of type *_PBLinks__Repr) to type PBLinks
./ipldsch_satisfaction.go:2754:26: cannot convert n (variable of type PBNode) to type *_PBNode__Repr

What did you expect to see?

No error, just like previous versions of Go:

$ go version
go version go1.22.3 linux/amd64
$ go build
$ echo $?
0

[gopherbot]

Change https://go.dev/cl/587075 mentions this issue: types2, go/types: fix pointer types check during typecheck conversions

[cuonglm]

This is an issue with types2 (and go/types), not the cmd/go.

Minimal reproducer:

package p

type _s struct{}
type s = *_s

type _s_repr _s

func (n s) M() any {
	return (*_s_repr)(n)
}

[mvdan]

This is an issue with types2 (and go/types), not the cmd/go.

I'm not familiar with compiler internals, so I just file the issue with a generic title first :)

[gopherbot]

Change https://go.dev/cl/587156 mentions this issue: go/types, types2: add missing Unalias calls (clarification)

[gopherbot]

Change https://go.dev/cl/587159 mentions this issue: go/types, types2: operand.convertibleTo must consider alias types

[mvdan]

Thank you for the quick fix!