cmd/compile: generic method appears to use syntax keywords as types

[denis-tingaikin]

What version of Go are you using (go version)?

$ go version
go version go1.18 darwin/arm64

Does this issue reproduce with the latest release?

Yes (1.18)

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
go env
GO111MODULE="on"
GOARCH="arm64"
GOBIN=""
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="darwin"
GOINSECURE=""
GOOS="darwin"
GOPROXY="https://goproxy.io,https://mirrors.aliyun.com/goproxy/"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOVCS=""
GOVERSION="go1.18"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/yv/fd8s2yw54cldnj29jx3qxrh80000gn/T/go-build4280234465=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

See at https://gotipplay.golang.org/p/Zb7hPmoxFj0 and https://go.dev/play/p/Zb7hPmoxFj0

type AwesomeSlice[T any] []T

// Are you expect this compilable?
func (s AwesomeSlice[nil]) AwesomeMethod1() nil {
	var panic nil
	return panic
}

What did you expect to see?

Compile errors

What did you see instead?

Everything is working

[ianlancetaylor]

In Go nil is not a keyword. It is a predeclared identifier (https://go.dev/ref/spec#Predeclared_identifiers). Code is permitted to shadow the predeclared identifiers, and that is what is happening here.

Closing because this is not a bug. In general we suggest asking questions on a forum; see https://go.dev/wiki/Questions. Thanks.