cmd/go: panic with invalid characters in build directory

[merlinz01]

Go version

go version go1.23.2 linux/amd64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/xxx/.cache/go-build'
GOENV='/home/xxx/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/xxx/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/xxx/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.23.2'
GODEBUG=''
GOTELEMETRY='on'
GOTELEMETRYDIR='/home/xxx/.config/go/telemetry'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/my/project/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 -ffile-prefix-map=/tmp/go-build1703176901=/tmp/go-build -gno-record-gcc-switches'

What did you do?

Run the command go build "^\n" in any directory in a bash terminal.

What did you see happen?

$ go build "^\n"
panic: path "^\\n" not in error "invalid import path \"^\\\\n\"" [recovered]
	panic: path "^\\n" not in error "invalid import path \"^\\\\n\""

goroutine 1 [running]:
cmd/go/internal/load.(*preload).flush(0xc000039270)
	cmd/go/internal/load/pkg.go:1082 +0x74
panic({0xa24c40?, 0xc000039320?})
	runtime/panic.go:785 +0x132
cmd/go/internal/load.ImportErrorf({0x7fffabb57f95, 0x3}, {0xaff36f?, 0x3?}, {0xc0001b5398?, 0xc0001b5710?, 0x0?})
	cmd/go/internal/load/pkg.go:542 +0x174
cmd/go/internal/load.(*Package).load(0xc0001c4008, {0xc1a0f0, 0xfefbc0}, {0x0, 0x0, 0x0, 0x1, 0x0, 0x0}, {0x7fffabb57f95, ...}, ...)
	cmd/go/internal/load/pkg.go:1901 +0x1214
cmd/go/internal/load.loadImport({0xc1a0f0, 0xfefbc0}, {0x0, 0x0, 0x0, 0x1, 0x0, 0x0}, 0xc000039270, {0x7fffabb57f95, ...}, ...)
	cmd/go/internal/load/pkg.go:744 +0x52f
cmd/go/internal/load.PackagesAndErrors({0xc1a0f0?, 0xfefbc0?}, {0x0, 0x0, 0x0, 0x1, 0x0, 0x0}, {0xc0000224a0, 0x1, ...})
	cmd/go/internal/load/pkg.go:2837 +0xa0b
cmd/go/internal/work.runBuild({0xc1a0f0, 0xfefbc0}, 0xc0000286a8?, {0xc0000224a0, 0x1, 0x1})
	cmd/go/internal/work/build.go:470 +0xe8
main.invoke(0xfc1300, {0xc000022490, 0x2, 0x2})
	cmd/go/main.go:299 +0x84e
main.main()
	cmd/go/main.go:213 +0xea5

What did you expect to see?

malformed import path "^": invalid char '^'

[cagedmantis]

@matloob @samthanawalla