Proposal: runtime: Error propagation not issued for function parameters if not used within function body.

[sankets8793]

Go version

go version go1.23.2 X:boringcrypto linux/amd64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/root/.cache/go-build'
GOENV='/root/.config/go/env'
GOEXE=''
GOEXPERIMENT='boringcrypto'
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/root/go/pkg/mod'
GONOPROXY='gitlab.eng.vmware.com,github.com/google/martian'
GONOSUMDB='*.eng.vmware.com'
GOOS='linux'
GOPATH='/root/go'
GOPRIVATE='gitlab.eng.vmware.com,github.com/google/martian'
GOPROXY='http://avi-buildops-cache-server-blr.avilb.broadcom.net:9090,https://packages.vcfd.broadcom.net/srp-mds-go-remote,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 X:boringcrypto'
GODEBUG=''
GOTELEMETRY='local'
GOTELEMETRYDIR='/root/.config/go/telemetry'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='x86_64-vmk-linux-gnu-gcc'
CXX='x86_64-vmk-linux-gnu-g++'
CGO_ENABLED='0'
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 -m64 -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build2580294929=/tmp/go-build -gno-record-gcc-switches'

What did you do?

https://go.dev/play/p/a4Xm3Eidkd0

What did you see happen?

In above mentioned snippet i.e https://go.dev/play/p/a4Xm3Eidkd0 , demoStr is declared as parameter to function but never used within function.

What did you expect to see?

In above mentioned snippet i.e. https://go.dev/play/p/a4Xm3Eidkd0 , This should raise error for demoStr as its not being used within function, agnostic of caller is passing or not. If its defined as parameter it should be consumed.

[sankets8793]

@gopherbot, please add labels NeedsFix

[sankets8793]

@gopherbot, please add labels compiler/runtime

[gazerro]

A function may not use one of its parameters in the following cases:

• The function implements a method of an interface and does not need to use the parameter. In some cases, it may still be preferable to keep the parameter name instead of replacing it with the blank identifier.

• A refactor has been done on an exported function, and the parameter is no longer used. For compatibility reasons, the parameter must be retained. From my perspective, it is better to keep the parameter name and document that it is no longer used, rather than replacing it with a blank identifier without any explanation in the documentation.

That said, the proposed change is not backward-compatible and would require modifying existing code.

[seankhliao]

Duplicate of #39118

[gabyhelp]

Related Issues

• gopls isn't emitting warnings #30932 (closed)
• x/tools/gopls: unusedparams analysis does not check exported functions #65401 (closed)
• proposal: cmd/compile: provide 'evaluated but not used' error when function returned from another function is not used (called or assigned) #29428 (closed)
• compiler: dead code and labels cause compilation failure #66803 (closed)
• x/tools/gopls: Warn UnusedVar for unused assign #56598 (closed)

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