// https://golang.org/design/36460-lazy-module-loading.)
				need := <-needc
				need[m] = true
				needc <- need
			}
		})
	}
	<-ld.work.Idle()

	need := <-needc
	if len(need) == 0 {
		return false // No roots to add.
	}

	toAdd := make([]module.Version, 0, len(need))
	for m := range need {
		toAdd = append(toAdd, m)
	}
	gover.ModSort(toAdd)

// The behavior of AssignableTo is unspecified if V or T is Typ[Invalid] or an
// uninstantiated generic type.
func AssignableTo(V, T Type) bool {
	x := operand{mode: value, typ: V}
	ok, _ := x.assignableTo(nil, T, nil) // check not needed for non-constant x
	return ok
}

// ConvertibleTo reports whether a value of type V is convertible to a value of
// type T.
//
// The behavior of ConvertibleTo is unspecified if V or T is Typ[Invalid] or an

	IsCmdList           bool // running as part of go list; set p.Stale and additional fields below
	NeedError           bool // list needs p.Error
	NeedExport          bool // list needs p.Export
	NeedCompiledGoFiles bool // list needs p.CompiledGoFiles
	AllowErrors         bool // errors don't immediately exit the program

	objdirSeq int // counter for NewObjdir
	pkgSeq    int

	if cfg.BuildModExplicit {
		return fmt.Sprintf("updates to go.mod needed, disabled by -mod=%v; to update it:\n\tgo mod tidy", cfg.BuildMod)
	}
	if cfg.BuildModReason != "" {
		return fmt.Sprintf("updates to go.mod needed, disabled by -mod=%s\n\t(%s)\n\tto update it:\n\tgo mod tidy", cfg.BuildMod, cfg.BuildModReason)
	}
	return "updates to go.mod needed; to update it:\n\tgo mod tidy"
}

var errGoModDirty error = goModDirtyError{}

With no arguments, download applies to the modules needed to build and test
the packages in the main module: the modules explicitly required by the main
module if it is at 'go 1.17' or higher, or all transitively-required modules
if at 'go 1.16' or lower.

The go command will automatically download modules as needed during ordinary
execution. The "go mod download" command is useful mainly for pre-filling

		//
		extra := po.newnode(nil)
		if (i1^i2)&1 != 0 { // non-deterministic
			po.setchl(extra, i1r)
			po.setchr(extra, e2)
			po.setchr(i1, newedge(extra, false))
			po.upush(undoSetChr, i1, i1r)
		} else {
			po.setchl(extra, i1l)
			po.setchr(extra, e2)
			po.setchl(i1, newedge(extra, false))
			po.upush(undoSetChl, i1, i1l)
		}
	}
}

// newnode allocates a new node bound to SSA value n.

// (file caching, HTTP fetches, and so on) needed by the [Client].
// The methods must be safe for concurrent use by multiple goroutines.
type ClientOps interface {
	// ReadRemote reads and returns the content served at the given path
	// on the remote database server. The path begins with "/lookup" or "/tile/",
	// and there is no need to parse the path in any way.

The main benefits of this system are that cmd/link remains relatively simple
(it does not need to implement a complete ELF and Mach-O linker) and
that gcc is not needed after the package is compiled. For example,
package net uses cgo for access to name resolution functions provided
by libc. Although gcc is needed to compile package net, gcc is not
needed to link programs that import package net.

Runtime

//     root.
//
// If any module that provided a package has been upgraded above its previous
// version, the caller may need to reload and recompute the package graph.
//
// To ensure that the loading process eventually converges, the caller should
// add any needed roots from the tidy root set (without removing existing untidy
// roots) until the set of roots has converged.

// non-7-bit clean bytes turn into %xx. The period needs escaping only in the
// last segment of the path, and it makes for happier users if we escape that as
// little as possible.
func PathToPrefix(s string) string {
	slash := strings.LastIndex(s, "/")
	// check for chars that need escaping
	n := 0
	for r := 0; r < len(s); r++ {