x/tools/go/packages:declared but not used

[lvyahui8]

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

$ go version  go1.17.6 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
GO111MODULE="on"
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/xxxxx/Library/Caches/go-build"
GOENV="/Users/xxxxx/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/xxxxx/go/pkg/mod"
GONOPROXY="xxxxxxxx"
GONOSUMDB="xxxxxxxx"
GOOS="darwin"
GOPATH="/Users/xxxxx/go"
GOPRIVATE="xxxxxxxx"
GOPROXY="xxxxxxxxx"
GOROOT="/usr/local/Cellar/go/1.17.6/libexec"
GOSUMDB="sum.golang.google.cn"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.17.6/libexec/pkg/tool/darwin_amd64"
GOVCS=""
GOVERSION="go1.17.6"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -arch x86_64 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/p0/kb961x5d6wd79gfp2h6t_8500000gn/T/go-build1578457773=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

I have written a simple program. It contains variables that are defined but not used. It can be successfully compiled to executable program, but when I load the package with golang analysis tool, I get the error that it is defined but not used.

package main

import (
	"fmt"
	"golang.org/x/tools/go/packages"
)

func main() {
	rootDir := "/tmp/example"
	cfg := &packages.Config{
		Mode:  packages.LoadAllSyntax,
		Tests: false,
		Dir:   rootDir,
	}
	packageArr, _ := packages.Load(cfg)
	fmt.Printf("pkg err : %+v", packageArr[0].Errors)
}

err output

pkg err : [/tmp/example/main.go:11:4: vv declared but not used]

What did you expect to see?

I would like to see a consistent behavior of the compilation tools, either fail or both succeed.

What did you see instead?

inconsistent results

[seankhliao]

Duplicate of #3059