mainModule,
				{Path: "go", Version: goVersion},
				{Path: "toolchain", Version: gover.LocalToolchain()},
			}
		} else {
			goVersion = gover.Local()
			pruning = pruningForGoVersion(goVersion)
			roots = []module.Version{
				{Path: "go", Version: goVersion},
				{Path: "toolchain", Version: gover.LocalToolchain()},
			}
		}
		rawGoVersion.Store(mainModule, goVersion)

		compatVersion := ld.TidyCompatibleVersion
		goVersion := ld.requirements.GoVersion()
		if compatVersion == "" {
			if gover.Compare(goVersion, gover.GoStrictVersion) < 0 {
				compatVersion = gover.Prev(goVersion)
			} else {
				// Starting at GoStrictVersion, we no longer maintain compatibility with
				// versions older than what is listed in the go.mod file.
				compatVersion = goVersion
			}
		}

	goversion := fmt.Sprintf("go1.%d", goversion.Version)
	for _, v := range []string{
		goversion,
		goversion + ".0",
		goversion + ".1",
		goversion + ".rc",
	} {
		conf := Config{GoVersion: v}
		pkg := mustTypecheck("package p", &conf, nil)
		if pkg.GoVersion() != conf.GoVersion {
			t.Errorf("got %s; want %s", pkg.GoVersion(), conf.GoVersion)
		}
	}
}

	//
	// Note that we lightly parse internal/goversion/goversion.go to
	// obtain the base version. We can't just import the package,
	// because cmd/dist is built with a bootstrap GOROOT which could
	// be an entirely different version of Go. We assume
	// that the file contains "const Version = <Integer>".
	goversionSource := readfile(pathf("%s/src/internal/goversion/goversion.go", goroot))

	goversion := fmt.Sprintf("go1.%d", goversion.Version)
	for _, v := range []string{
		goversion,
		goversion + ".0",
		goversion + ".1",
		goversion + ".rc",
	} {
		conf := Config{GoVersion: v}
		pkg := mustTypecheck("package p", &conf, nil)
		if pkg.GoVersion() != conf.GoVersion {
			t.Errorf("got %s; want %s", pkg.GoVersion(), conf.GoVersion)
		}
	}
}

func LoadModGraph(ctx context.Context, goVersion string) (*ModuleGraph, error) {
	rs, err := loadModFile(ctx, nil)
	if err != nil {
		return nil, err
	}

	if goVersion != "" {
		v, _ := rs.rootSelected("go")
		if gover.Compare(v, gover.GoStrictVersion) >= 0 && gover.Compare(goVersion, v) < 0 {

			// go: directive (but be conservative and test)
			if strings.HasPrefix(text, "go:") {
				if p.top && strings.HasPrefix(msg, "//go:build") {
					if x, err := constraint.Parse(msg); err == nil {
						p.goVersion = constraint.GoVersion(x)
					}
				}
				if pragh != nil {
					p.pragma = pragh(p.posAt(line, col+2), p.scanner.blank, text, p.pragma) // +2 to skip over // or /*
				}
			}
		},
		directives,
	)

	for {
		p.pos, p.tok, p.lit = p.scanner.Scan()
		if p.tok == token.COMMENT {
			if p.top && strings.HasPrefix(p.lit, "//go:build") {
				if x, err := constraint.Parse(p.lit); err == nil {
					p.goVersion = constraint.GoVersion(x)
				}
			}
			if p.mode&ParseComments == 0 {
				continue
			}
		} else {
			// Found a non-comment; top of file is over.
			p.top = false
		}
		break
	}
}

	tg.grepStdout("-ffaster", "CC arguments not found")

	tg.run("env", "GOVERSION")
	envVersion := strings.TrimSpace(tg.stdout.String())

	tg.run("version")
	cmdVersion := strings.TrimSpace(tg.stdout.String())

	// If 'go version' is "go version <version> <goos>/<goarch>", then
	// 'go env GOVERSION' is just "<version>".
	if cmdVersion == envVersion || !strings.Contains(cmdVersion, envVersion) {

package build

import (
	"bytes"
	"errors"
	"fmt"
	"go/ast"
	"go/build/constraint"
	"go/doc"
	"go/token"
	"internal/buildcfg"
	"internal/godebug"
	"internal/goroot"
	"internal/goversion"
	"internal/platform"
	"io"
	"io/fs"
	"os"
	"os/exec"
	pathpkg "path"
	"path/filepath"
	"runtime"
	"slices"
	"strconv"
	"strings"
	"unicode"
	"unicode/utf8"
	_ "unsafe" // for linkname