cmd/compile: type arguments for generic aliases are not checked against type parameter constraints #69576
Description
Go version
go version devel go1.24-c208b91395 Fri Sep 20 13:54:44 2024 +0000 X:aliastypeparams linux/amd64
Output of go env in your module/workspace:
GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/mneverov/.cache/go-build'
GOENV='/home/mneverov/.config/go/env'
GOEXE=''
GOEXPERIMENT='aliastypeparams'
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/mneverov/go/pkg/mod'
GONOPROXY='gitlab.in.strato.de,github.com/ionos-cloud'
GONOSUMDB='gitlab.in.strato.de,github.com/ionos-cloud'
GOOS='linux'
GOPATH='/home/mneverov/go'
GOPRIVATE='gitlab.in.strato.de,github.com/ionos-cloud'
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/mneverov/go/src/github.com/golang/go'
GOSUMDB='sum.golang.org'
GOTMPDIR='/home/mneverov/tmp'
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/mneverov/go/src/github.com/golang/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='devel go1.24-c208b91395 Fri Sep 20 13:54:44 2024 +0000 X:aliastypeparams'
GODEBUG=''
GOTELEMETRY='on'
GOTELEMETRYDIR='/home/mneverov/.config/go/telemetry'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/home/mneverov/go/src/github.com/mneverov/usealias/go.mod'
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=/home/mneverov/tmp/go-build764456494=/tmp/go-build -gno-record-gcc-switches'What did you do?
see in playground
// GOEXPERIMENT=aliastypeparams
package main
import "fmt"
type T[P int] struct{ f P }
type A[P int] = T[P]
func main() {
var ta A[string]
fmt.Printf("%#v\n", ta)
}What did you see happen?
The output is main.T[string]{f:""}
What did you expect to see?
error string does not satisfy int (string missing in int)
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