x/text: gotext nil dereferences when a const declaration is in another file #60555
Description
What version of Go are you using (go version)?
$ go version go version go1.20.4 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="" GOARCH="amd64" GOBIN="" GOCACHE="/home/aron/.cache/go-build" GOENV="/home/aron/.config/go/env" GOEXE="" GOEXPERIMENT="" GOFLAGS="" GOHOSTARCH="amd64" GOHOSTOS="linux" GOINSECURE="" GOMODCACHE="/home/aron/go/pkg/mod" GONOPROXY="" GONOSUMDB="" GOOS="linux" GOPATH="/home/aron/go" GOPRIVATE="" GOPROXY="https://proxy.golang.org,direct" GOROOT="/snap/go/current" GOSUMDB="sum.golang.org" GOTMPDIR="" GOTOOLDIR="/snap/go/current/pkg/tool/linux_amd64" GOVCS="" GOVERSION="go1.20.4" GCCGO="/usr/bin/gccgo" GOAMD64="v1" AR="ar" CC="gcc" CXX="g++" CGO_ENABLED="1" GOMOD="/home/aron/text/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 -fdebug-prefix-map=/tmp/go-build922970473=/tmp/go-build -gno-record-gcc-switches"
What did you do?
login.go
package mvp
import (
"golang.org/x/text/language"
"golang.org/x/text/message"
)
const alreadyLoggedInMessage = "You're already logged in"
func LoginStuff() {
message.NewPrinter(language.MustParse("hu-HU")).Sprintf(alreadyLoggedInMessage)
}
register.go
package mvp
import (
"golang.org/x/text/language"
"golang.org/x/text/message"
)
func RegisterStuff() {
message.NewPrinter(language.MustParse("hu-HU")).Sprintf(alreadyLoggedInMessage)
}
Then I called gotext via gotext -srclang=en-US update -out=catalog.go -lang=en-US,hu-HU {package name}
I get the following panic:
"runtime error: invalid memory address or nil pointer dereference"
Stack:
4 0x00000000009975f9 in golang.org/x/text/message/pipeline.packageExtracter.handleCall
at /home/aron/text/message/pipeline/extract.go:600
5 0x0000000000996725 in golang.org/x/text/message/pipeline.(*extracter).extractMessages.func3
at /home/aron/text/message/pipeline/extract.go:545
6 0x000000000058791d in go/ast.inspector.Visit
at /snap/go/current/src/go/ast/walk.go:386
7 0x00000000005839ba in go/ast.Walk
at /snap/go/current/src/go/ast/walk.go:51
8 0x000000000058565b in go/ast.Walk
at /snap/go/current/src/go/ast/walk.go:206
9 0x0000000000583787 in go/ast.walkStmtList
at /snap/go/current/src/go/ast/walk.go:32
10 0x0000000000585c53 in go/ast.Walk
at /snap/go/current/src/go/ast/walk.go:234
11 0x000000000058703e in go/ast.Walk
at /snap/go/current/src/go/ast/walk.go:357
12 0x00000000005838e7 in go/ast.walkDeclList
at /snap/go/current/src/go/ast/walk.go:38
13 0x0000000000587169 in go/ast.Walk
at /snap/go/current/src/go/ast/walk.go:366
14 0x00000000005879e5 in go/ast.Inspect
at /snap/go/current/src/go/ast/walk.go:397
15 0x0000000000996427 in golang.org/x/text/message/pipeline.(*extracter).extractMessages
at /home/aron/text/message/pipeline/extract.go:542
16 0x0000000000991c46 in golang.org/x/text/message/pipeline.Extract
at /home/aron/text/message/pipeline/extract.go:50
17 0x00000000009aba9c in main.runUpdate
at /home/aron/text/cmd/gotext/update.go:35
18 0x00000000009a90c3 in main.main
at /home/aron/text/cmd/gotext/main.go:149
As far as I understand it seems to happen because in extract.go ident.Obj is nil when extracting messages from register.go, since the the declaration is in the other file (according to #48141).
Indeed modifying the relevant code to something like:
if obj := ident.Obj; obj != nil {
if v, ok := obj.Decl.(*ast.ValueSpec); ok && v.Comment != nil {
// TODO: get comment above ValueSpec as well
comment = v.Comment.Text()
}
}
apparently fixes the problem.
What did you expect to see?
No panic.
What did you see instead?
A panic.