x/tools/go/analysis/passes/slog: nil panic in `isAttr` via `analysisutil.IsNamed`

[fsouza]

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

$ go version
go version devel go1.21-39c5070712 Thu Jul 6 23:23:41 2023 +0000 darwin/arm64

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=''
GOARCH='arm64'
GOBIN='/Users/fsouza/bin'
GOCACHE='/Users/fsouza/Library/Caches/go-build'
GOENV='/Users/fsouza/Library/Application Support/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS='-modcacherw'
GOHOSTARCH='arm64'
GOHOSTOS='darwin'
GOINSECURE=''
GOMODCACHE='/Users/fsouza/.cache/go/path/pkg/mod'
GONOPROXY='git.sr.ht'
GONOSUMDB='git.sr.ht'
GOOS='darwin'
GOPATH='/Users/fsouza/.cache/go/path'
GOPRIVATE='git.sr.ht'
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/Users/fsouza/.cache/go/sdk/gotip'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/Users/fsouza/.cache/go/sdk/gotip/pkg/tool/darwin_arm64'
GOVCS=''
GOVERSION='devel go1.21-39c5070712 Thu Jul 6 23:23:41 2023 +0000'
GCCGO='gccgo'
AR='ar'
CC='clang'
CXX='clang++'
CGO_ENABLED='1'
GOMOD='/Users/fsouza/Projects/os/p/s3-upload-proxy/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 -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -ffile-prefix-map=/var/folders/rz/8d0l4yp51sd3jh9f34x7pkg80000gn/T/go-build1879486314=/tmp/go-build -gno-record-gcc-switches -fno-common'

What did you do?

$ go test -c

The s3-upload-proxy package was using slog from golang.org/x/exp/slog, and I wanted to migrate it to the standard library one (see PR: fsouza/s3-upload-proxy#511). I ran into a weird issue when trying to run tests though, and since the error happens in a package that doesn't have any tests, I realized that the issue happened during compilation and tried to run go test -c to see what would happen, and voila, there's the error.

I tried creating a smaller reproducer, but failed to do so. Unfortunately I don't have much time in my hands to try to dig into this issue, so I figured I could report it in case someone else has more time. It's possible that I'm doing something very wrong here, but even in that case, I'm not sure if getting a panic from the build process is the right thing to do?

Steps to reproduce from "scratch":

％ git clone -b build-with-1.21rc2 https://github.com/fsouza/s3-upload-proxy.git
％ go -C s3-upload-proxy test -c

What did you expect to see?

Successful compilation of the test binary.

What did you see instead?

％ go test -c
# github.com/fsouza/s3-upload-proxy
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x8 pc=0x1043fa738]

goroutine 44 [running]:
go/types.(*Package).Path(...)
        ../../../../.cache/go/sdk/gotip/src/go/types/package.go:33
cmd/vendor/golang.org/x/tools/go/analysis/passes/internal/analysisutil.IsNamed(...)
        ../../../../.cache/go/sdk/gotip/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/internal/analysisutil/util.go:126
cmd/vendor/golang.org/x/tools/go/analysis/passes/slog.isAttr(...)
        ../../../../.cache/go/sdk/gotip/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/slog/slog.go:142
cmd/vendor/golang.org/x/tools/go/analysis/passes/slog.run.func1({0x1044fa680?, 0x14000191c40})
        ../../../../.cache/go/sdk/gotip/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/slog/slog.go:90 +0x268
cmd/vendor/golang.org/x/tools/go/ast/inspector.(*Inspector).Preorder(0x1400081a000, {0x140006a3be8?, 0x1?, 0x104236e2c?}, 0x140006a3bf8)
        ../../../../.cache/go/sdk/gotip/src/cmd/vendor/golang.org/x/tools/go/ast/inspector/inspector.go:81 +0x98
cmd/vendor/golang.org/x/tools/go/analysis/passes/slog.run(0x140007240d0)
        ../../../../.cache/go/sdk/gotip/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/slog/slog.go:55 +0x8c
cmd/vendor/golang.org/x/tools/go/analysis/unitchecker.run.func5.1()
        ../../../../.cache/go/sdk/gotip/src/cmd/vendor/golang.org/x/tools/go/analysis/unitchecker/unitchecker.go:354 +0x734
sync.(*Once).doSlow(0x1044ab720?, 0x140001a5470?)
        ../../../../.cache/go/sdk/gotip/src/sync/once.go:74 +0x100
sync.(*Once).Do(...)
        ../../../../.cache/go/sdk/gotip/src/sync/once.go:65
cmd/vendor/golang.org/x/tools/go/analysis/unitchecker.run.func5(0x10468f060)
        ../../../../.cache/go/sdk/gotip/src/cmd/vendor/golang.org/x/tools/go/analysis/unitchecker/unitchecker.go:305 +0x134
cmd/vendor/golang.org/x/tools/go/analysis/unitchecker.run.func6.1(0x0?)
        ../../../../.cache/go/sdk/gotip/src/cmd/vendor/golang.org/x/tools/go/analysis/unitchecker/unitchecker.go:376 +0x34
created by cmd/vendor/golang.org/x/tools/go/analysis/unitchecker.run.func6 in goroutine 1
        ../../../../.cache/go/sdk/gotip/src/cmd/vendor/golang.org/x/tools/go/analysis/unitchecker/unitchecker.go:375 +0x4c

[seankhliao]

Reproduced on tip.
The panic is in vet, run as part of tests.

Simpler reproducer:

package main

import (
	"errors"
	"log/slog"
)

func main() {
	err := errors.New("xxx")
	slog.Error("foo", err)
}

cc @jba

[gopherbot]

Change https://go.dev/cl/508822 mentions this issue: src/cmd: re-vendor tools

[jba]

Tools was vendored in via a different CL. This should be fixed.