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cmd/compile: inaccurate compiler error on duplicate wasmexport symbol #68982

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johanbrandhorst opened this issue Aug 21, 2024 · 3 comments
Open

cmd/compile: inaccurate compiler error on duplicate wasmexport symbol #68982

johanbrandhorst opened this issue Aug 21, 2024 · 3 comments
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@cherrymui
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compiler/runtime Issues related to the Go compiler and/or runtime. NeedsFix The path to resolution is known, but the work has not been done.
Milestone
Go1.24

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@johanbrandhorst
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Go version

tip

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='arm64'
GOBIN=''
GOCACHE='/home/johan/.cache/go-build'
GOENV='/home/johan/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='arm64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/johan/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/johan/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/johan/src/tip/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/johan/src/tip/go/pkg/tool/linux_arm64'
GOVCS=''
GOVERSION='devel go1.24-24fd1a043d Tue Aug 20 23:11:53 2024  0000'
GODEBUG=''
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/johan/.config/go/telemetry'
GCCGO='gccgo'
GOARM64='v8.0'
AR='ar'
CC='gcc'
CXX='g  '
CGO_ENABLED='0'
GOMOD='/home/johan/src/tip/go/test/wasmexport/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 -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build2688758080=/tmp/go-build -gno-record-gcc-switches'

What did you do?

I created a package that exported two identical symbols (in the same package) using the go:wasmexport compiler directive.

package main

//go:wasmexport A
func A() int64 {
	return 10
}

//go:wasmexport A
func B() int64 {
	return 10
}

func main() {
}

What did you see happen?

I saw a compiler error:

$ GOARCH=wasm GOOS=wasip1 go build -buildmode=c-shared -o x.wasm main.go
main.go:5:2: <autogenerated>:1: symbol A redeclared
        <unknown line number>: other declaration of symbol A

What did you expect to see?

The error message should be able to point to the line number of both symbols:

$ GOARCH=wasm GOOS=wasip1 go build -buildmode=c-shared -o x.wasm main.go
main.go:5:2: <autogenerated>:1: symbol A redeclared
        main.go:10:2: other declaration of symbol A

It is also notable that main.go:5 is the location of the return, not the compiler directive.
@gopherbot gopherbot added the compiler/runtime Issues related to the Go compiler and/or runtime. label Aug 21, 2024
@johanbrandhorst
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CC @golang/wasm

@gabyhelp
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Related Issues and Documentation

(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)

@mknyszek mknyszek modified the milestones: Go1.23.1, Go1.24 Aug 21, 2024
@mknyszek mknyszek added the NeedsFix The path to resolution is known, but the work has not been done. label Aug 21, 2024
@cuonglm
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cuonglm commented Aug 26, 2024

It seems to me this is unfortunate.

  • The main.go:5:2 part of error message is the current position in the source code, not part of the error message emited by obj.Link.InitTextSym.
  • We are creating export wrapper functions, that's why we see <autogenerated>:1.

Could we simply use the wrapped function position for wrapper ones instead of auto generated? cc @cherrymui

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@cherrymui cherrymui

Labels
compiler/runtime Issues related to the Go compiler and/or runtime. NeedsFix The path to resolution is known, but the work has not been done.
Projects
Go Compiler / Runtime
Status: Todo
Milestone
Go1.24
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6 participants
@mknyszek @cuonglm @johanbrandhorst @gopherbot @cherrymui @gabyhelp