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cmd/cgo: go build failed on _cgo_main.c if there's '#cgo CFLAGS: -W -Werror' in cgo preamble #43639

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hzzb opened this issue Jan 12, 2021 · 2 comments
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cmd/cgo: go build failed on _cgo_main.c if there's '#cgo CFLAGS: -W -Werror' in cgo preamble #43639

hzzb opened this issue Jan 12, 2021 · 2 comments
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@hzzb
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hzzb commented Jan 12, 2021

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

$ go version
go version go1.12.8 darwin/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
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/hans/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/hans/golang"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/hans/github.com/hzzb/go/src/go.mod"
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=/var/folders/42/38j1_hsd0ql20_c0g6hcgxww0000gn/T/go-build122131844=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

demo code: https://play.golang.org/p/JybuNyX-bqf

cd to the package directory containing above two files and run go build

What did you expect to see?

go build ran successfully and nothing outputted

What did you see instead?

_cgo_main.c:2:23: error: unused parameter 'fn' [-Werror,-Wunused-parameter]
_cgo_main.c:2:61: error: unused parameter 'a' [-Werror,-Wunused-parameter]
_cgo_main.c:2:68: error: unused parameter 'c' [-Werror,-Wunused-parameter]
_cgo_main.c:2:85: error: unused parameter 'ctxt' [-Werror,-Wunused-parameter]
_cgo_main.c:4:41: error: unused parameter 'ctxt' [-Werror,-Wunused-parameter]
_cgo_main.c:6:26: error: unused parameter 'a' [-Werror,-Wunused-parameter]
_cgo_main.c:6:33: error: unused parameter 'c' [-Werror,-Wunused-parameter]
_cgo_main.c:7:23: error: unused parameter 'a' [-Werror,-Wunused-parameter]
_cgo_main.c:7:30: error: unused parameter 'c' [-Werror,-Wunused-parameter]
hzzb added a commit to hzzb/go that referenced this issue Jan 12, 2021
@hzzb
cmd/cgo: fix unused parameter warnings in generated _cgo_main.c
a7684e2 
Applying -Werror compiler option to request warnings is an usual
way to discover potential errors. Go user may put a cgo directive
in preamble: `// #cgo CFLAGS: -Werror=unused-parameter`.

However, the directive also takes effect on the cgo generated files.
I cleaned _cgo_main.c to help Go user only concentrate on warnings
of their own file.

Fixes golang#43639
@hzzb hzzb mentioned this issue Jan 12, 2021
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@gopherbot
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Change https://golang.org/cl/283232 mentions this issue: cmd/cgo: fix unused parameter warnings in generated _cgo_main.c

hzzb added a commit to hzzb/go that referenced this issue Jan 12, 2021
@hzzb
cmd/cgo: fix unused parameter warnings in generated _cgo_main.c
a431a7b 
Applying -Werror compiler option to request warnings is an usual
way to discover potential errors. Go user may put a cgo directive
in preamble: `// #cgo CFLAGS: -Werror=unused-parameter`.

However, the directive also takes effect on the cgo generated files.
I cleaned _cgo_main.c to help Go user only concentrate on warnings
of their own file.

Fixes golang#43639
@bcmills bcmills added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Jan 12, 2021
@bcmills bcmills added this to the Backlog milestone Jan 12, 2021
@hzzb hzzb mentioned this issue May 25, 2021
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@gopherbot
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Change https://golang.org/cl/322232 mentions this issue: Cmd/cgo/fix unused parameter warning

@golang golang locked and limited conversation to collaborators Aug 16, 2022
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