base.Fatalf("go: -require=%s: %v", arg, err)
		}
	})
}

// flagDropRequire implements the -droprequire flag.
func flagDropRequire(arg string) {
	path := parsePath("droprequire", arg)
	edits = append(edits, func(f *modfile.File) {
		if err := f.DropRequire(path); err != nil {
			base.Fatalf("go: -droprequire=%s: %v", arg, err)
		}
	})
}

// flagExclude implements the -exclude flag.

go mod verify

# Packages below module root should not be mentioned in go.sum.
rm go.sum
go mod edit -droprequire rsc.io/quote
go get rsc.io/quote/buggy
grep '^rsc.io/quote v1.5.2/go.mod ' go.sum
! grep buggy go.sum

# non-existent packages below module root should not be mentioned in go.sum
go mod edit -droprequire rsc.io/quote
! go list rsc.io/quote/morebuggy
grep '^rsc.io/quote v1.5.2/go.mod ' go.sum
! grep buggy go.sum

# 'go clean -modcache' should not download anything before cleaning.
go mod edit -require rsc.io/quote@v1.99999999.0-not-a-real-version
go clean -modcache
! stderr 'finding rsc.io'
go mod edit -droprequire rsc.io/quote

! go clean -modcache m
stderr 'go: clean -modcache cannot be used with package arguments'

-- go.mod --
module m
-- m.go --
package m

-- r/go.mod --
module example.com/r

go get github.com/rsc/legacytest@master
go list -m all
stdout '^github.com/rsc/legacytest v2\.0\.1-0\.\d{14}-7303f7796364\+incompatible$'

# get should include incompatible tags in "latest" calculation.
go mod edit -droprequire github.com/rsc/legacytest
go get github.com/rsc/legacytest@latest
go list
go list -m all
stdout '^github.com/rsc/legacytest v2\.0\.0\+incompatible$'

# v2.0.1-0.pseudo+incompatible
go get ...test@7303f77

cmpenv go.mod $WORK/go.mod.init

# go mod edits
go mod edit -droprequire=x.1 -require=x.1@v1.0.0 -require=x.2@v1.1.0 -droprequire=x.2 -exclude='x.1 @ v1.2.0' -exclude=x.1@v1.2.1 -exclude=x.1@v2.0.0+incompatible -replace=x.1@v1.3.0=y.1@v1.4.0 -replace='x.1@v1.4.0 = ../z' -retract=v1.6.0 -retract=[v1.1.0,v1.2.0] -retract=[v1.3.0,v1.4.0] -retract=v1.0.0
cmpenv go.mod $WORK/go.mod.edit1

stdout '^patch.example.com/depofdirectpatch v1.0.0'

# ...but 'all@patch' should fail if any of the affected modules do not already
# have a selected version.
cp go.mod.orig go.mod
go mod edit -droprequire=patch.example.com/direct
cp go.mod go.mod.dropped
! go get all@patch
stderr '^go: all@patch: can''t query version "patch" of module patch.example.com/direct: no existing version is required$'
cmp go.mod.dropped go.mod

cp go.mod.orig go.mod
go mod edit -require=example.com/badchain/a@v1.1.0
! go list -m all
cmp stderr list-expected

# Try listing a package that imports a package
# in a module without a requirement.
go mod edit -droprequire example.com/badchain/a
! go list -mod=mod m/use
cmp stderr list-missing-expected

! go list -mod=mod -test m/testuse
cmp stderr list-missing-test-expected

-- go.mod.orig --
module m

go 1.13

grep rsc.io/quote go.alt.sum
go mod verify
go mod why rsc.io/quote


# 'go list' and other commands with build flags should work.
# They should update the alternate go.mod when a dependency is missing.
go mod edit -droprequire rsc.io/quote
go list -mod=mod .
grep rsc.io/quote go.alt.mod
go build -n -mod=mod .
go test -n -mod=mod .
go get rsc.io/quote


# 'go mod vendor' should work.
go mod vendor
exists vendor

! go list -deps example.net/cmd/tool
stderr '^module example\.net/cmd provides package example\.net/cmd/tool and is replaced but not required; to add it:\n\tgo get example\.net/cmd@v0\.1\.0$'
go mod edit -droprequire example.net/tools


# 'go get' makes a best effort to fetch those dependencies, but shouldn't
# error out if dependencies of tag-guarded files are missing.

go get example.net/tools@v0.1.0

go get rsc.io/fortune
go install -trimpath rsc.io/fortune
exec $WORK/paths-a.exe $GOPATH/bin/fortune$GOEXE
stdout 'binary contains module root: false'
stdout 'binary contains an empty GOROOT'
go mod edit -droprequire rsc.io/fortune

# Two binaries built from identical packages in different directories
# should be identical.
cd $WORK/b/src/paths
go build -trimpath -o $WORK/paths-b.exe
cmp -q $WORK/paths-a.exe $WORK/paths-b.exe