cmd/compile: go:linkname causes "internal compiler error: panic: runtime error: invalid memory address or nil pointer dereference"

[mandriota]

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

$ go version
go version go1.20.3 darwin/arm64

Does this issue reproduce with the latest release?

Yes, i downloaded the latest release from https://go.dev/doc/install.

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

go env Output

$ go env
GO111MODULE=""
GOARCH="arm64"
GOBIN=""
GOCACHE="/Users/mark/Library/Caches/go-build"
GOENV="/Users/mark/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/mark/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/mark/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_arm64"
GOVCS=""
GOVERSION="go1.20.3"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/dev/null"
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 -fdebug-prefix-map=/var/folders/82/wm5sqy_936zclxgk95t9wghr0000gn/T/go-build3292674194=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

https://go.dev/play/p/P2iv3ERVhbb

What did you expect to see?

A regular compiler error, not internal panic.

What did you see instead?

# command-line-arguments
./main.go:6:6: internal compiler error: panic: runtime error: invalid memory address or nil pointer dereference

Please file a bug report including a short program that triggers the error.
https://go.dev/issue/new

[dr2chase]

@golang/compiler

[prattmic]

The tip playground shows the actual stack trace:

./prog.go:6:6: internal compiler error: panic: runtime error: invalid memory address or nil pointer dereference

goroutine 1 [running]:
runtime/debug.Stack()
	/usr/local/go/src/runtime/debug/stack.go:24 +0x5e
cmd/compile/internal/base.FatalfAt({0x7ff12108?, 0x7f70?}, {0xd46d3e, 0x9}, {0xc0001234f8, 0x1, 0x1})
	/usr/local/go/src/cmd/compile/internal/base/print.go:234 +0x1d7
cmd/compile/internal/base.Fatalf(...)
	/usr/local/go/src/cmd/compile/internal/base/print.go:203
cmd/compile/internal/gc.handlePanic()
	/usr/local/go/src/cmd/compile/internal/gc/main.go:52 +0x90
panic({0xcca7a0?, 0x1356e40?})
	/usr/local/go/src/runtime/panic.go:913 +0x21f
cmd/internal/obj.(*Link).InitTextSym(0xc000158400, 0xc000414c80, 0x30?, {0x30?, 0x0?})
	/usr/local/go/src/cmd/internal/obj/plist.go:172 +0xd8
cmd/compile/internal/ir.setupTextLSym(0x7f7058b7fc68?, 0x7f707ff12108?)
	/usr/local/go/src/cmd/compile/internal/ir/abi.go:80 +0x1e7
cmd/compile/internal/ir.InitLSym(0xc000403b80, 0x1)
	/usr/local/go/src/cmd/compile/internal/ir/abi.go:32 +0x114
cmd/compile/internal/gc.prepareFunc(0xc000403b80)
	/usr/local/go/src/cmd/compile/internal/gc/compile.go:90 +0x25
cmd/compile/internal/gc.enqueueFunc(0xc000403b80)
	/usr/local/go/src/cmd/compile/internal/gc/compile.go:71 +0x307
cmd/compile/internal/gc.Main(0xd7a4e0)
	/usr/local/go/src/cmd/compile/internal/gc/main.go:363 +0x1b0a
main.main()
	/usr/local/go/src/cmd/compile/main.go:57 +0xf9

Looks like a panic trying to print a build error at https://cs.opensource.google/go/go/+/master:src/cmd/internal/obj/plist.go;l=172;drc=76ac54b50ea39bbb1389ecfed71f4f0991cb4289. I'd guess s.Func().Text is nil?

[thanm]

This is not a supported use of //go:linkname, sorry. We use //go:linkname internall within the Go runtime, it is not intended as a general-purpose means of renaming one function to another.

[prattmic]

I think this warrants fixing. This use of linkname isn't supported, but it shouldn't crash the compiler.

[mdempsky]

I agree it would be better that the compiler never crashed, but I also agree with @thanm that //go:linkname is a power-user feature and it's being used outside of its intended usage in the reported example. ICE isn't ideal, but reporting a better error here seems pretty low priority IMO.

[gopherbot]

Change https://go.dev/cl/484759 mentions this issue: cmd/compile: fallback if s.Func().Text is nil