cmd/go: 'vet' and 'test' duplicate flags from GOFLAGS if they are also specified explicitly

[elagergren-spideroak]

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

$ go version
1.12.5

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
darwin/amd64

What did you do?

Set GOFLAGS=-vet=off then ran go test -vet=all.

What did you expect to see?

go test ... to not error out.

What did you see instead?

$ GOFLAGS=-test.vet=off go test -test.vet all
# _/tmp/bar
./bar_test.go:6:2: Logf format %f has arg X of wrong type string
FAIL	_/tmp/bar [build failed]

$ GOFLAGS=-vet=off go test -vet all
go test: vet flag may be set only once
run "go help test" or "go help testflag" for more information

$ GOFLAGS=-test.vet=off go test -vet all
# _/tmp/bar
./bar_test.go:6:2: Logf format %f has arg X of wrong type string
FAIL	_/tmp/bar [build failed]

$ GOFLAGS=-vet=off go test -test.vet all
go test: vet flag may be set only once
run "go help test" or "go help testflag" for more information

[elagergren-spideroak]

Similarly, GOFLAGS="-vet=all -vet=off" go test -v does not work. Related to #29053

[dmitshur]

/cc @jayconrod @bcmills

[bcmills]

What happens for the other flags with the test. prefix, such as -test.v and -test.run?

We should probably at least make -vet consistent with those.

[elagergren-spideroak]

$ GOFLAGS=-test.v go test -test.v=false
# _/tmp/bar
./bar_test.go:6:2: Logf format %f has arg X of wrong type string
FAIL	_/tmp/bar [build failed]

$ GOFLAGS=-test.v go test -v=false
# _/tmp/bar
./bar_test.go:6:2: Logf format %f has arg X of wrong type string
FAIL	_/tmp/bar [build failed]

$ GOFLAGS=-v go test -v=false
go test: v flag may be set only once
run "go help test" or "go help testflag" for more information

$ GOFLAGS=-v go test -test.v=false
go test: v flag may be set only once
run "go help test" or "go help testflag" for more information

[elagergren-spideroak]

-test.run exhibits the same behavior as -test.v and -test.vet.

[agnivade]

The errors seem to be consistent for all flags.

@elagergren-spideroak - It's not clear from the issue description, but for GOFLAGS=-vet=off go test -vet all, did you want the vet=all value to override the vet=off value set in GOFLAGS ?

[amenzhinsky]

I'm having the same problem with persistent environment variables, even if I set the corresponding env var to an empty string:

go env -w GOFLAGS="-trimpath"
GOFLAGS= go test -trimpath # or simply "go test -trimpath"

go test: trimpath flag may be set only once
run "go help test" or "go help testflag" for more information

[amenzhinsky]

It seems only go test and go vet have the issue, everything is alright with the others.

[elagergren-spideroak]

@agnivade Yeah, sorry. From the docs:

GOFLAGS
	...
        Flags listed on the command line
	are applied after this list and therefore override it.