x/tools/go/ssa: panic in ssa.(*Program).needMethods with type parameters

[ainar-g]

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

$ go version
go version devel go1.18-78b4518e31 Thu Dec 9 17:16:12 2021 +0000 linux/amd64

Does this issue reproduce with the latest release?

Yes.

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

go env Output

$ go env
GO111MODULE="on"
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/ainar/.cache/go-build"
GOENV="/home/ainar/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/ainar/go/pkg/mod"
GONOPROXY="REMOVED"
GONOSUMDB="REMOVED"
GOOS="linux"
GOPATH="/home/ainar/go"
GOPRIVATE="REMOVED"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/ainar/go/tip"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/ainar/go/tip/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="devel go1.18-78b4518e31 Thu Dec 9 17:16:12 2021 +0000"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/home/ainar/dev/tmp/go/tmp/go.mod"
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 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build3880243860=/tmp/go-build -gno-record-gcc-switches"

What did you do?

1. Install any analyser that uses golang.org/x/tools/go/ssa. I've tried nilness and unparam.

2. Try running it on the following code:

   package main
   
   import "fmt"
   
   func main() {
   	F(42)
   }
   
   func F[T any](v T) {
   	fmt.Println(v)
   }

What did you expect to see?

No errors.

What did you see instead?

nilness .

panic: T

goroutine 354 [running]:
golang.org/x/tools/go/ssa.(*Program).needMethods(0xc00022a9c0, {0x7b5a60?, 0xc000116900?}, 0x0)
        /home/ainar/go/pkg/mod/golang.org/x/tools@v0.1.9-0.20211209154716-27fc7644e1ac/go/ssa/methods.go:237 +0x5b1
golang.org/x/tools/go/ssa.(*Program).needMethods(0xc00022a9c0, {0x7b5a38?, 0xc0004629d8?}, 0x0)
        /home/ainar/go/pkg/mod/golang.org/x/tools@v0.1.9-0.20211209154716-27fc7644e1ac/go/ssa/methods.go:233 +0x708
golang.org/x/tools/go/ssa.(*Program).needMethods(0xc00022a9c0, {0x7b59c0?, 0xc0006bde80?}, 0x0)
        /home/ainar/go/pkg/mod/golang.org/x/tools@v0.1.9-0.20211209154716-27fc7644e1ac/go/ssa/methods.go:209 +0x448
golang.org/x/tools/go/ssa.(*Program).needMethodsOf(0xc00022a9c0, {0x7b59c0?, 0xc0006bde80?})
        /home/ainar/go/pkg/mod/golang.org/x/tools@v0.1.9-0.20211209154716-27fc7644e1ac/go/ssa/methods.go:145 +0x70
golang.org/x/tools/go/ssa.(*Package).build(0xc0000ec240)
        /home/ainar/go/pkg/mod/golang.org/x/tools@v0.1.9-0.20211209154716-27fc7644e1ac/go/ssa/builder.go:2281 +0x111
sync.(*Once).doSlow(0xc00022a9c0?, 0xc00027f450?)
        /home/ainar/go/tip/src/sync/once.go:68 +0xc2
[…]

[timothy-king]

Duplicate of #48525. x/tools/go/ssa and packages based on it, like nilness, do not yet support code containing generics. FWIW I am actively working to address this.