}
	if cfg.BuildMod == "vendor" {
		// Even if the main module is in the module cache,
		// its vendored dependencies are not loaded from their
		// usual cached locations.
		return nil, errNotFromModuleCache
	}
	modroot = filepath.Clean(modroot)
	if str.HasFilePathPrefix(modroot, cfg.GOROOTsrc) || !str.HasFilePathPrefix(modroot, cfg.GOMODCACHE) {
		return nil, errNotFromModuleCache
	}

// be indexed because it contains symlinks.
func indexModule(modroot string) ([]byte, error) {
	fsys.Trace("indexModule", modroot)
	var packages []*rawPackage

	// If the root itself is a symlink to a directory,
	// we want to follow it (see https://go.dev/issue/50807).
	// Add a trailing separator to force that to happen.
	root := str.WithFilePathSeparator(modroot)

	// Copy testdata into GOPATH/src/cgostdio, along with a go.mod file
	// declaring the same path.
	modRoot := filepath.Join(GOPATH, "src", "cgostdio")
	if err := cgotest.OverlayDir(modRoot, "testdata"); err != nil {
		log.Panic(err)
	}
	if err := os.Chdir(modRoot); err != nil {
		log.Panic(err)
	}
	os.Setenv("PWD", modRoot)
	if err := os.WriteFile("go.mod", []byte("module cgostdio\n"), 0666); err != nil {
		log.Panic(err)
	}

	// Copy testdata into GOPATH/src/cgolife, along with a go.mod file
	// declaring the same path.
	modRoot := filepath.Join(GOPATH, "src", "cgolife")
	if err := cgotest.OverlayDir(modRoot, "testdata"); err != nil {
		log.Panic(err)
	}
	if err := os.Chdir(modRoot); err != nil {
		log.Panic(err)
	}
	os.Setenv("PWD", modRoot)
	if err := os.WriteFile("go.mod", []byte("module cgolife\n"), 0666); err != nil {
		log.Panic(err)
	}

	for _, d := range wf.Use {
		modRoot := d.Path
		if !filepath.IsAbs(modRoot) {
			modRoot = filepath.Join(workDir, modRoot)
		}

		if seen[modRoot] {
			return nil, nil, fmt.Errorf("error loading go.work:\n%s:%d: path %s appears multiple times in workspace", base.ShortPath(path), d.Syntax.Start.Line, modRoot)
		}
		seen[modRoot] = true
		modRoots = append(modRoots, modRoot)
	}

	for _, g := range wf.Godebug {

			walkPkgs(filepath.Join(cfg.GOROOTsrc, "cmd"), "cmd", pruneGoMod)
		}
	}

	if cfg.BuildMod == "vendor" {
		for _, mod := range MainModules.Versions() {
			if modRoot := MainModules.ModRoot(mod); modRoot != "" {
				walkPkgs(modRoot, MainModules.PathPrefix(mod), pruneGoMod|pruneVendor)
			}
		}
		if HasModRoot() {
			walkPkgs(VendorDir(), "", pruneVendor)
		}
		return
	}

					return module.Version{}, MainModules.ModRoot(mainModule), dir, nil, err
				} else if ok {
					return mainModule, MainModules.ModRoot(mainModule), dir, nil, nil
				}
			}
		}
		dir := filepath.Join(cfg.GOROOTsrc, path)
		modroot = cfg.GOROOTsrc
		if str.HasPathPrefix(path, "cmd") {
			modroot = filepath.Join(cfg.GOROOTsrc, "cmd")
		}

# Test a replacement with an absolute path (so the path isn't
# cleaned by having filepath.Abs called on it). This checks
# whether the modindex logic cleans the modroot path before using
# it.

[!GOOS:windows] skip
[short] skip

go run print_go_mod.go # use this program to write a go.mod with an absolute path
cp stdout go.mod

go list -modfile=go.mod all
-- print_go_mod.go --
//go:build ignore
package main

import (
    "fmt"

	os.Setenv("PWD", altRoot)
	goCmd(nil, "build", "-buildmode=plugin", "-o", filepath.Join(modRoot, "plugin-mismatch.so"), "./plugin-mismatch")

	os.Setenv("GOPATH", GOPATH)
	if err := os.Chdir(modRoot); err != nil {
		log.Panic(err)
	} else {
		prettyPrintf("cd %s\n", modRoot)
	}
	os.Setenv("PWD", modRoot)

	os.Setenv("LD_LIBRARY_PATH", modRoot)

	goCmd(nil, "build", "-buildmode=plugin", "./plugin1")

	var goV string
	for _, m := range mms.Versions() {
		if mms.ModRoot(m) == "" && m.Path == "command-line-arguments" {
			// This is not a real module.
			// TODO(#49228): Remove this special case once the special
			// command-line-arguments module is gone.
			continue
		}

		// Use EnterModule to reset the global state in modload to be in
		// single-module mode using the modroot of m.
		modload.EnterModule(ctx, mms.ModRoot(m))