cmd/vet: exit code should be 1 in case a problem is reported, not 2

[perillo]

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

$ go version
go version go1.16.3 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="on"
GOARCH="amd64"
GOBIN="/home/manlio/.local/bin"
GOCACHE="/home/manlio/.cache/go-build"
GOENV="/home/manlio/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE="*.local"
GOMODCACHE="/home/manlio/.local/lib/go/pkg/mod"
GONOPROXY=""
GONOSUMDB="*.local"
GOOS="linux"
GOPATH="/home/manlio/.local/lib/go:/home/manlio/src/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/lib/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.16.3"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/dev/null"
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 -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build541737785=/tmp/go-build -gno-record-gcc-switches"
GOROOT/bin/go version: go version go1.16.3 linux/amd64
GOROOT/bin/go tool compile -V: compile version go1.16.3
uname -sr: Linux 5.11.11-arch1-1
/usr/lib/libc.so.6: GNU C Library (GNU libc) release release version 2.33.
gdb --version: GNU gdb (GDB) 10.1

Currently go vet exit code is 2 both when it is invoked incorrectly (e.g. flags) and a problem is reported.

I think that in the case a problem is reported, go vet exit code should be 1 instead of 2, to differentiate the two cases.

[perillo]

The problem seems to be in cmd/go/internal/worker and errPrintedOutput:

// errPrintedOutput is a special error indicating that a command failed
// but that it generated output as well, and that output has already
// been printed, so there's no point showing 'exit status 1' or whatever
// the wait status was. The main executor, builder.do, knows not to
// print this error.

[mknyszek]

CC @alandonovan who is listed as the owner of vet via https://dev.golang.org/owners. Though I'm going to throw in @matloob because I suspect that's out of date.

[zpavlinovic]

I can see this distinction being useful. Is there a sense of how many things this change would break?