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cmd/cgo: undefined reference when using referencing static functions #34831

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abacabadabacaba opened this issue Oct 10, 2019 · 7 comments
Closed

cmd/cgo: undefined reference when using referencing static functions #34831

abacabadabacaba opened this issue Oct 10, 2019 · 7 comments
Labels
FrozenDueToAge help wanted NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.
Milestone
Unplanned

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

$ go version
go version go1.13.1 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="/path/to/home/.cache/go-build"
GOENV="/path/to/home/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/path/to/home/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/lib/go-1.13"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/go-1.13/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build344992079=/tmp/go-build -gno-record-gcc-switches"

What did you do?

I tried to compile the following program:

package main

// static void f() { }
import "C"

func main() {
	_ = C.f
}

What did you expect to see?

I expected it to compile successfully.

What did you see instead?

# _/path/to/test
/usr/bin/ld: $WORK/b001/_cgo_main.o:/tmp/go-build/cgo-generated-wrappers:2: undefined reference to `f'
collect2: error: ld returned 1 exit status
@ianlancetaylor
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Note that calling C.f works fine.

@ianlancetaylor ianlancetaylor added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Oct 10, 2019
@ianlancetaylor ianlancetaylor added this to the Unplanned milestone Oct 10, 2019
@shawndx
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shawndx commented Dec 4, 2019

Note that calling C.f works fine.

cgo generates wrapper of a 'C.f' even it's 'static', is it expected behavior of cgo?

@ianlancetaylor
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Yes. But please take discussions of how cgo works to golang-nuts, not this issue. Thanks.

@AdamSLevy
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How do you work around this?

@ianlancetaylor
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@AdamSLevy Use a Go function literal. For example,

_ = func() { C.f() }

@qmuntal
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qmuntal commented Jan 10, 2021

Possibly related to #19836

@bcmills
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bcmills commented Nov 9, 2021

Duplicate of #19836

@bcmills bcmills marked this as a duplicate of #19836 Nov 9, 2021
@bcmills bcmills closed this as completed Nov 9, 2021
@golang golang locked and limited conversation to collaborators Nov 9, 2022
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Milestone
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7 participants
@ianlancetaylor @qmuntal @bcmills @AdamSLevy @abacabadabacaba @gopherbot @shawndx