if d > 0 && d < bestDepth {
					best = path
					bestDepth = d
				}
			}
			why := modload.Why(best)
			if why == "" {
				vendoring := ""
				if *whyVendor {
					vendoring = " to vendor"
				}
				why = "(main module does not need" + vendoring + " module " + m.Path + ")\n"
			}
			fmt.Printf("%s# %s\n%s", sep, m.Path, why)
			sep = "\n"
		}
	} else {
		// Resolve to packages.

-- modules.txt.required_but_not_explicit --
## workspace
# example.com/p v1.0.0 => ./p
## go 1.21
# example.com/q v1.0.0 => ./q
## explicit; go 1.21
-- required_but_not_explicit_error.txt --
go: inconsistent vendoring in $GOPATH${/}src:
	example.com/p@v1.0.0: is explicitly required in go.mod, but not marked as explicit in vendor/modules.txt

	To ignore the vendor directory, use -mod=readonly or -mod=mod.
	To sync the vendor directory, run:

cp go.mod go.mod.orig

# For modules whose go.mod file does not include a 'go' directive,
# we assume the language and dependency semantics of Go 1.16,
# but do not trigger “automatic vendoring” mode (-mod=vendor),
# which was added in Go 1.14 and was not triggered
# under the same conditions in Go 1.16 (which would instead
# default to -mod=readonly when no 'go' directive is present).

# For Go 1.16 modules, 'all' should prune out dependencies of tests,

go get
grep 'rsc.io/quote' go.mod

# Tidying the module should preserve those dependencies.
go mod tidy
grep 'rsc.io/quote' go.mod

[short] stop

# Vendoring the module's dependencies should work too.
go mod vendor
exists vendor/rsc.io/quote

# The same should work in directories with names starting with underscores.
cd $WORK/_ignored
go mod init testdata.tld/foo

env GO111MODULE=on

# Replacement should not use a vendor directory as the target.
! go mod vendor
stderr 'replacement path ./vendor/not-rsc.io/quote/v3 inside vendor directory'

cp go.mod1 go.mod
rm -r vendor

# Before vendoring, we expect to see the original directory.
go list -f '{{with .Module}}{{.Version}}{{end}} {{.Dir}}' rsc.io/quote/v3
stdout 'v3.0.0'
stdout '.*[/\\]not-rsc.io[/\\]quote[/\\]v3'

# In GOPATH mode, module legacy support does path rewriting very similar to vendoring.

env GO111MODULE=off

go list -f '{{range .Imports}}{{.}}{{"\n"}}{{end}}' old/p1
stdout ^new/p1$

go list -f '{{range .Imports}}{{.}}{{"\n"}}{{end}}' new/p1
stdout ^new/p2$           # not new/v2/p2
! stdout ^new/v2
stdout ^new/sub/x/v1/y$   # not new/sub/v2/x/v1/y
! stdout ^new/sub/v2
stdout ^new/sub/inner/x # not new/sub/v2/inner/x

go build old/p1 new/p1

type gcimports struct {
	packages map[string]*types2.Package
	lookup   func(path string) (io.ReadCloser, error)
}

func (m *gcimports) Import(path string) (*types2.Package, error) {
	return m.ImportFrom(path, "" /* no vendoring */, 0)
}

func (m *gcimports) ImportFrom(path, srcDir string, mode types2.ImportMode) (*types2.Package, error) {
	if mode != 0 {
		panic("mode must be 0")
	}

# A 'go 1.13' vendor/modules.txt file is not usually sufficient
# to pass those checks.
go mod edit -go=1.14

! go list -f {{.Dir}} -tags tools all
stderr '^go: inconsistent vendoring in '$WORK[/\\]auto':$'
stderr '^\texample.com/printversion@v1.0.0: is explicitly required in go.mod, but not marked as explicit in vendor/modules.txt'

type gcimports struct {
	fset     *token.FileSet
	packages map[string]*types.Package
	lookup   Lookup
}

func (m *gcimports) Import(path string) (*types.Package, error) {
	return m.ImportFrom(path, "" /* no vendoring */, 0)
}

func (m *gcimports) ImportFrom(path, srcDir string, mode types.ImportMode) (*types.Package, error) {
	if mode != 0 {
		panic("mode must be 0")
	}

must not already exist.

Init accepts one optional argument, the module path for the new module. If the
module path argument is omitted, init will attempt to infer the module path
using import comments in .go files, vendoring tool configuration files (like
Gopkg.lock), and the current directory (if in GOPATH).

See https://golang.org/ref/mod#go-mod-init for more about 'go mod init'.
`,
	Run: runInit,
}

func init() {