gccgo.go

Documentation: cmd/go/internal/work

     1  // Copyright 2011 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package work
     6  
     7  import (
     8  	"bytes"
     9  	"fmt"
    10  	"os"
    11  	"os/exec"
    12  	"path/filepath"
    13  	"strings"
    14  	"sync"
    15  
    16  	"cmd/go/internal/base"
    17  	"cmd/go/internal/cfg"
    18  	"cmd/go/internal/fsys"
    19  	"cmd/go/internal/load"
    20  	"cmd/go/internal/str"
    21  	"cmd/internal/pkgpath"
    22  )
    23  
    24  // The Gccgo toolchain.
    25  
    26  type gccgoToolchain struct{}
    27  
    28  var GccgoName, GccgoBin string
    29  var gccgoErr error
    30  
    31  func init() {
    32  	GccgoName = cfg.Getenv("GCCGO")
    33  	if GccgoName == "" {
    34  		GccgoName = "gccgo"
    35  	}
    36  	GccgoBin, gccgoErr = cfg.LookPath(GccgoName)
    37  }
    38  
    39  func (gccgoToolchain) compiler() string {
    40  	checkGccgoBin()
    41  	return GccgoBin
    42  }
    43  
    44  func (gccgoToolchain) linker() string {
    45  	checkGccgoBin()
    46  	return GccgoBin
    47  }
    48  
    49  func (gccgoToolchain) ar() []string {
    50  	return envList("AR", "ar")
    51  }
    52  
    53  func checkGccgoBin() {
    54  	if gccgoErr == nil {
    55  		return
    56  	}
    57  	fmt.Fprintf(os.Stderr, "cmd/go: gccgo: %s\n", gccgoErr)
    58  	base.SetExitStatus(2)
    59  	base.Exit()
    60  }
    61  
    62  func (tools gccgoToolchain) gc(b *Builder, a *Action, archive string, importcfg, embedcfg []byte, symabis string, asmhdr bool, pgoProfile string, gofiles []string) (ofile string, output []byte, err error) {
    63  	p := a.Package
    64  	sh := b.Shell(a)
    65  	objdir := a.Objdir
    66  	out := "_go_.o"
    67  	ofile = objdir + out
    68  	gcargs := []string{"-g"}
    69  	gcargs = append(gcargs, b.gccArchArgs()...)
    70  	gcargs = append(gcargs, "-fdebug-prefix-map="+b.WorkDir+"=/tmp/go-build")
    71  	gcargs = append(gcargs, "-gno-record-gcc-switches")
    72  	if pkgpath := gccgoPkgpath(p); pkgpath != "" {
    73  		gcargs = append(gcargs, "-fgo-pkgpath="+pkgpath)
    74  	}
    75  	if p.Internal.LocalPrefix != "" {
    76  		gcargs = append(gcargs, "-fgo-relative-import-path="+p.Internal.LocalPrefix)
    77  	}
    78  
    79  	args := str.StringList(tools.compiler(), "-c", gcargs, "-o", ofile, forcedGccgoflags)
    80  	if importcfg != nil {
    81  		if b.gccSupportsFlag(args[:1], "-fgo-importcfg=/dev/null") {
    82  			if err := sh.writeFile(objdir+"importcfg", importcfg); err != nil {
    83  				return "", nil, err
    84  			}
    85  			args = append(args, "-fgo-importcfg="+objdir+"importcfg")
    86  		} else {
    87  			root := objdir + "_importcfgroot_"
    88  			if err := buildImportcfgSymlinks(sh, root, importcfg); err != nil {
    89  				return "", nil, err
    90  			}
    91  			args = append(args, "-I", root)
    92  		}
    93  	}
    94  	if embedcfg != nil && b.gccSupportsFlag(args[:1], "-fgo-embedcfg=/dev/null") {
    95  		if err := sh.writeFile(objdir+"embedcfg", embedcfg); err != nil {
    96  			return "", nil, err
    97  		}
    98  		args = append(args, "-fgo-embedcfg="+objdir+"embedcfg")
    99  	}
   100  
   101  	if b.gccSupportsFlag(args[:1], "-ffile-prefix-map=a=b") {
   102  		if cfg.BuildTrimpath {
   103  			args = append(args, "-ffile-prefix-map="+base.Cwd()+"=.")
   104  			args = append(args, "-ffile-prefix-map="+b.WorkDir+"=/tmp/go-build")
   105  		}
   106  		if fsys.OverlayFile != "" {
   107  			for _, name := range gofiles {
   108  				absPath := mkAbs(p.Dir, name)
   109  				overlayPath, ok := fsys.OverlayPath(absPath)
   110  				if !ok {
   111  					continue
   112  				}
   113  				toPath := absPath
   114  				// gccgo only applies the last matching rule, so also handle the case where
   115  				// BuildTrimpath is true and the path is relative to base.Cwd().
   116  				if cfg.BuildTrimpath && str.HasFilePathPrefix(toPath, base.Cwd()) {
   117  					toPath = "." + toPath[len(base.Cwd()):]
   118  				}
   119  				args = append(args, "-ffile-prefix-map="+overlayPath+"="+toPath)
   120  			}
   121  		}
   122  	}
   123  
   124  	args = append(args, a.Package.Internal.Gccgoflags...)
   125  	for _, f := range gofiles {
   126  		f := mkAbs(p.Dir, f)
   127  		// Overlay files if necessary.
   128  		// See comment on gctoolchain.gc about overlay TODOs
   129  		f, _ = fsys.OverlayPath(f)
   130  		args = append(args, f)
   131  	}
   132  
   133  	output, err = sh.runOut(p.Dir, nil, args)
   134  	return ofile, output, err
   135  }
   136  
   137  // buildImportcfgSymlinks builds in root a tree of symlinks
   138  // implementing the directives from importcfg.
   139  // This serves as a temporary transition mechanism until
   140  // we can depend on gccgo reading an importcfg directly.
   141  // (The Go 1.9 and later gc compilers already do.)
   142  func buildImportcfgSymlinks(sh *Shell, root string, importcfg []byte) error {
   143  	for lineNum, line := range strings.Split(string(importcfg), "\n") {
   144  		lineNum++ // 1-based
   145  		line = strings.TrimSpace(line)
   146  		if line == "" {
   147  			continue
   148  		}
   149  		if line == "" || strings.HasPrefix(line, "#") {
   150  			continue
   151  		}
   152  		var verb, args string
   153  		if i := strings.Index(line, " "); i < 0 {
   154  			verb = line
   155  		} else {
   156  			verb, args = line[:i], strings.TrimSpace(line[i+1:])
   157  		}
   158  		before, after, _ := strings.Cut(args, "=")
   159  		switch verb {
   160  		default:
   161  			base.Fatalf("importcfg:%d: unknown directive %q", lineNum, verb)
   162  		case "packagefile":
   163  			if before == "" || after == "" {
   164  				return fmt.Errorf(`importcfg:%d: invalid packagefile: syntax is "packagefile path=filename": %s`, lineNum, line)
   165  			}
   166  			archive := gccgoArchive(root, before)
   167  			if err := sh.Mkdir(filepath.Dir(archive)); err != nil {
   168  				return err
   169  			}
   170  			if err := sh.Symlink(after, archive); err != nil {
   171  				return err
   172  			}
   173  		case "importmap":
   174  			if before == "" || after == "" {
   175  				return fmt.Errorf(`importcfg:%d: invalid importmap: syntax is "importmap old=new": %s`, lineNum, line)
   176  			}
   177  			beforeA := gccgoArchive(root, before)
   178  			afterA := gccgoArchive(root, after)
   179  			if err := sh.Mkdir(filepath.Dir(beforeA)); err != nil {
   180  				return err
   181  			}
   182  			if err := sh.Mkdir(filepath.Dir(afterA)); err != nil {
   183  				return err
   184  			}
   185  			if err := sh.Symlink(afterA, beforeA); err != nil {
   186  				return err
   187  			}
   188  		case "packageshlib":
   189  			return fmt.Errorf("gccgo -importcfg does not support shared libraries")
   190  		}
   191  	}
   192  	return nil
   193  }
   194  
   195  func (tools gccgoToolchain) asm(b *Builder, a *Action, sfiles []string) ([]string, error) {
   196  	p := a.Package
   197  	var ofiles []string
   198  	for _, sfile := range sfiles {
   199  		base := filepath.Base(sfile)
   200  		ofile := a.Objdir + base[:len(base)-len(".s")] + ".o"
   201  		ofiles = append(ofiles, ofile)
   202  		sfile, _ = fsys.OverlayPath(mkAbs(p.Dir, sfile))
   203  		defs := []string{"-D", "GOOS_" + cfg.Goos, "-D", "GOARCH_" + cfg.Goarch}
   204  		if pkgpath := tools.gccgoCleanPkgpath(b, p); pkgpath != "" {
   205  			defs = append(defs, `-D`, `GOPKGPATH=`+pkgpath)
   206  		}
   207  		defs = tools.maybePIC(defs)
   208  		defs = append(defs, b.gccArchArgs()...)
   209  		err := b.Shell(a).run(p.Dir, p.ImportPath, nil, tools.compiler(), "-xassembler-with-cpp", "-I", a.Objdir, "-c", "-o", ofile, defs, sfile)
   210  		if err != nil {
   211  			return nil, err
   212  		}
   213  	}
   214  	return ofiles, nil
   215  }
   216  
   217  func (gccgoToolchain) symabis(b *Builder, a *Action, sfiles []string) (string, error) {
   218  	return "", nil
   219  }
   220  
   221  func gccgoArchive(basedir, imp string) string {
   222  	end := filepath.FromSlash(imp + ".a")
   223  	afile := filepath.Join(basedir, end)
   224  	// add "lib" to the final element
   225  	return filepath.Join(filepath.Dir(afile), "lib"+filepath.Base(afile))
   226  }
   227  
   228  func (tools gccgoToolchain) pack(b *Builder, a *Action, afile string, ofiles []string) error {
   229  	p := a.Package
   230  	sh := b.Shell(a)
   231  	objdir := a.Objdir
   232  	var absOfiles []string
   233  	for _, f := range ofiles {
   234  		absOfiles = append(absOfiles, mkAbs(objdir, f))
   235  	}
   236  	var arArgs []string
   237  	if cfg.Goos == "aix" && cfg.Goarch == "ppc64" {
   238  		// AIX puts both 32-bit and 64-bit objects in the same archive.
   239  		// Tell the AIX "ar" command to only care about 64-bit objects.
   240  		arArgs = []string{"-X64"}
   241  	}
   242  	absAfile := mkAbs(objdir, afile)
   243  	// Try with D modifier first, then without if that fails.
   244  	output, err := sh.runOut(p.Dir, nil, tools.ar(), arArgs, "rcD", absAfile, absOfiles)
   245  	if err != nil {
   246  		return sh.run(p.Dir, p.ImportPath, nil, tools.ar(), arArgs, "rc", absAfile, absOfiles)
   247  	}
   248  
   249  	// Show the output if there is any even without errors.
   250  	return sh.reportCmd("", "", output, nil)
   251  }
   252  
   253  func (tools gccgoToolchain) link(b *Builder, root *Action, out, importcfg string, allactions []*Action, buildmode, desc string) error {
   254  	sh := b.Shell(root)
   255  
   256  	// gccgo needs explicit linking with all package dependencies,
   257  	// and all LDFLAGS from cgo dependencies.
   258  	afiles := []string{}
   259  	shlibs := []string{}
   260  	ldflags := b.gccArchArgs()
   261  	cgoldflags := []string{}
   262  	usesCgo := false
   263  	cxx := false
   264  	objc := false
   265  	fortran := false
   266  	if root.Package != nil {
   267  		cxx = len(root.Package.CXXFiles) > 0 || len(root.Package.SwigCXXFiles) > 0
   268  		objc = len(root.Package.MFiles) > 0
   269  		fortran = len(root.Package.FFiles) > 0
   270  	}
   271  
   272  	readCgoFlags := func(flagsFile string) error {
   273  		flags, err := os.ReadFile(flagsFile)
   274  		if err != nil {
   275  			return err
   276  		}
   277  		const ldflagsPrefix = "_CGO_LDFLAGS="
   278  		for _, line := range strings.Split(string(flags), "\n") {
   279  			if strings.HasPrefix(line, ldflagsPrefix) {
   280  				flag := line[len(ldflagsPrefix):]
   281  				// Every _cgo_flags file has -g and -O2 in _CGO_LDFLAGS
   282  				// but they don't mean anything to the linker so filter
   283  				// them out.
   284  				if flag != "-g" && !strings.HasPrefix(flag, "-O") {
   285  					cgoldflags = append(cgoldflags, flag)
   286  				}
   287  			}
   288  		}
   289  		return nil
   290  	}
   291  
   292  	var arArgs []string
   293  	if cfg.Goos == "aix" && cfg.Goarch == "ppc64" {
   294  		// AIX puts both 32-bit and 64-bit objects in the same archive.
   295  		// Tell the AIX "ar" command to only care about 64-bit objects.
   296  		arArgs = []string{"-X64"}
   297  	}
   298  
   299  	newID := 0
   300  	readAndRemoveCgoFlags := func(archive string) (string, error) {
   301  		newID++
   302  		newArchive := root.Objdir + fmt.Sprintf("_pkg%d_.a", newID)
   303  		if err := sh.CopyFile(newArchive, archive, 0666, false); err != nil {
   304  			return "", err
   305  		}
   306  		if cfg.BuildN || cfg.BuildX {
   307  			sh.ShowCmd("", "ar d %s _cgo_flags", newArchive)
   308  			if cfg.BuildN {
   309  				// TODO(rsc): We could do better about showing the right _cgo_flags even in -n mode.
   310  				// Either the archive is already built and we can read them out,
   311  				// or we're printing commands to build the archive and can
   312  				// forward the _cgo_flags directly to this step.
   313  				return "", nil
   314  			}
   315  		}
   316  		err := sh.run(root.Objdir, desc, nil, tools.ar(), arArgs, "x", newArchive, "_cgo_flags")
   317  		if err != nil {
   318  			return "", err
   319  		}
   320  		err = sh.run(".", desc, nil, tools.ar(), arArgs, "d", newArchive, "_cgo_flags")
   321  		if err != nil {
   322  			return "", err
   323  		}
   324  		err = readCgoFlags(filepath.Join(root.Objdir, "_cgo_flags"))
   325  		if err != nil {
   326  			return "", err
   327  		}
   328  		return newArchive, nil
   329  	}
   330  
   331  	// If using -linkshared, find the shared library deps.
   332  	haveShlib := make(map[string]bool)
   333  	targetBase := filepath.Base(root.Target)
   334  	if cfg.BuildLinkshared {
   335  		for _, a := range root.Deps {
   336  			p := a.Package
   337  			if p == nil || p.Shlib == "" {
   338  				continue
   339  			}
   340  
   341  			// The .a we are linking into this .so
   342  			// will have its Shlib set to this .so.
   343  			// Don't start thinking we want to link
   344  			// this .so into itself.
   345  			base := filepath.Base(p.Shlib)
   346  			if base != targetBase {
   347  				haveShlib[base] = true
   348  			}
   349  		}
   350  	}
   351  
   352  	// Arrange the deps into afiles and shlibs.
   353  	addedShlib := make(map[string]bool)
   354  	for _, a := range root.Deps {
   355  		p := a.Package
   356  		if p != nil && p.Shlib != "" && haveShlib[filepath.Base(p.Shlib)] {
   357  			// This is a package linked into a shared
   358  			// library that we will put into shlibs.
   359  			continue
   360  		}
   361  
   362  		if haveShlib[filepath.Base(a.Target)] {
   363  			// This is a shared library we want to link against.
   364  			if !addedShlib[a.Target] {
   365  				shlibs = append(shlibs, a.Target)
   366  				addedShlib[a.Target] = true
   367  			}
   368  			continue
   369  		}
   370  
   371  		if p != nil {
   372  			target := a.built
   373  			if p.UsesCgo() || p.UsesSwig() {
   374  				var err error
   375  				target, err = readAndRemoveCgoFlags(target)
   376  				if err != nil {
   377  					continue
   378  				}
   379  			}
   380  
   381  			afiles = append(afiles, target)
   382  		}
   383  	}
   384  
   385  	for _, a := range allactions {
   386  		if a.Package == nil {
   387  			continue
   388  		}
   389  		if len(a.Package.CgoFiles) > 0 {
   390  			usesCgo = true
   391  		}
   392  		if a.Package.UsesSwig() {
   393  			usesCgo = true
   394  		}
   395  		if len(a.Package.CXXFiles) > 0 || len(a.Package.SwigCXXFiles) > 0 {
   396  			cxx = true
   397  		}
   398  		if len(a.Package.MFiles) > 0 {
   399  			objc = true
   400  		}
   401  		if len(a.Package.FFiles) > 0 {
   402  			fortran = true
   403  		}
   404  	}
   405  
   406  	wholeArchive := []string{"-Wl,--whole-archive"}
   407  	noWholeArchive := []string{"-Wl,--no-whole-archive"}
   408  	if cfg.Goos == "aix" {
   409  		wholeArchive = nil
   410  		noWholeArchive = nil
   411  	}
   412  	ldflags = append(ldflags, wholeArchive...)
   413  	ldflags = append(ldflags, afiles...)
   414  	ldflags = append(ldflags, noWholeArchive...)
   415  
   416  	ldflags = append(ldflags, cgoldflags...)
   417  	ldflags = append(ldflags, envList("CGO_LDFLAGS", "")...)
   418  	if cfg.Goos != "aix" {
   419  		ldflags = str.StringList("-Wl,-(", ldflags, "-Wl,-)")
   420  	}
   421  
   422  	if root.buildID != "" {
   423  		// On systems that normally use gold or the GNU linker,
   424  		// use the --build-id option to write a GNU build ID note.
   425  		switch cfg.Goos {
   426  		case "android", "dragonfly", "linux", "netbsd":
   427  			ldflags = append(ldflags, fmt.Sprintf("-Wl,--build-id=0x%x", root.buildID))
   428  		}
   429  	}
   430  
   431  	var rLibPath string
   432  	if cfg.Goos == "aix" {
   433  		rLibPath = "-Wl,-blibpath="
   434  	} else {
   435  		rLibPath = "-Wl,-rpath="
   436  	}
   437  	for _, shlib := range shlibs {
   438  		ldflags = append(
   439  			ldflags,
   440  			"-L"+filepath.Dir(shlib),
   441  			rLibPath+filepath.Dir(shlib),
   442  			"-l"+strings.TrimSuffix(
   443  				strings.TrimPrefix(filepath.Base(shlib), "lib"),
   444  				".so"))
   445  	}
   446  
   447  	var realOut string
   448  	goLibBegin := str.StringList(wholeArchive, "-lgolibbegin", noWholeArchive)
   449  	switch buildmode {
   450  	case "exe":
   451  		if usesCgo && cfg.Goos == "linux" {
   452  			ldflags = append(ldflags, "-Wl,-E")
   453  		}
   454  
   455  	case "c-archive":
   456  		// Link the Go files into a single .o, and also link
   457  		// in -lgolibbegin.
   458  		//
   459  		// We need to use --whole-archive with -lgolibbegin
   460  		// because it doesn't define any symbols that will
   461  		// cause the contents to be pulled in; it's just
   462  		// initialization code.
   463  		//
   464  		// The user remains responsible for linking against
   465  		// -lgo -lpthread -lm in the final link. We can't use
   466  		// -r to pick them up because we can't combine
   467  		// split-stack and non-split-stack code in a single -r
   468  		// link, and libgo picks up non-split-stack code from
   469  		// libffi.
   470  		ldflags = append(ldflags, "-Wl,-r", "-nostdlib")
   471  		ldflags = append(ldflags, goLibBegin...)
   472  
   473  		if nopie := b.gccNoPie([]string{tools.linker()}); nopie != "" {
   474  			ldflags = append(ldflags, nopie)
   475  		}
   476  
   477  		// We are creating an object file, so we don't want a build ID.
   478  		if root.buildID == "" {
   479  			ldflags = b.disableBuildID(ldflags)
   480  		}
   481  
   482  		realOut = out
   483  		out = out + ".o"
   484  
   485  	case "c-shared":
   486  		ldflags = append(ldflags, "-shared", "-nostdlib")
   487  		if cfg.Goos != "windows" {
   488  			ldflags = append(ldflags, "-Wl,-z,nodelete")
   489  		}
   490  		ldflags = append(ldflags, goLibBegin...)
   491  		ldflags = append(ldflags, "-lgo", "-lgcc_s", "-lgcc", "-lc", "-lgcc")
   492  
   493  	case "shared":
   494  		if cfg.Goos != "aix" {
   495  			ldflags = append(ldflags, "-zdefs")
   496  		}
   497  		ldflags = append(ldflags, "-shared", "-nostdlib", "-lgo", "-lgcc_s", "-lgcc", "-lc")
   498  
   499  	default:
   500  		base.Fatalf("-buildmode=%s not supported for gccgo", buildmode)
   501  	}
   502  
   503  	switch buildmode {
   504  	case "exe", "c-shared":
   505  		if cxx {
   506  			ldflags = append(ldflags, "-lstdc++")
   507  		}
   508  		if objc {
   509  			ldflags = append(ldflags, "-lobjc")
   510  		}
   511  		if fortran {
   512  			fc := cfg.Getenv("FC")
   513  			if fc == "" {
   514  				fc = "gfortran"
   515  			}
   516  			// support gfortran out of the box and let others pass the correct link options
   517  			// via CGO_LDFLAGS
   518  			if strings.Contains(fc, "gfortran") {
   519  				ldflags = append(ldflags, "-lgfortran")
   520  			}
   521  		}
   522  	}
   523  
   524  	if err := sh.run(".", desc, nil, tools.linker(), "-o", out, ldflags, forcedGccgoflags, root.Package.Internal.Gccgoflags); err != nil {
   525  		return err
   526  	}
   527  
   528  	switch buildmode {
   529  	case "c-archive":
   530  		if err := sh.run(".", desc, nil, tools.ar(), arArgs, "rc", realOut, out); err != nil {
   531  			return err
   532  		}
   533  	}
   534  	return nil
   535  }
   536  
   537  func (tools gccgoToolchain) ld(b *Builder, root *Action, targetPath, importcfg, mainpkg string) error {
   538  	return tools.link(b, root, targetPath, importcfg, root.Deps, ldBuildmode, root.Package.ImportPath)
   539  }
   540  
   541  func (tools gccgoToolchain) ldShared(b *Builder, root *Action, toplevelactions []*Action, targetPath, importcfg string, allactions []*Action) error {
   542  	return tools.link(b, root, targetPath, importcfg, allactions, "shared", targetPath)
   543  }
   544  
   545  func (tools gccgoToolchain) cc(b *Builder, a *Action, ofile, cfile string) error {
   546  	p := a.Package
   547  	inc := filepath.Join(cfg.GOROOT, "pkg", "include")
   548  	cfile = mkAbs(p.Dir, cfile)
   549  	defs := []string{"-D", "GOOS_" + cfg.Goos, "-D", "GOARCH_" + cfg.Goarch}
   550  	defs = append(defs, b.gccArchArgs()...)
   551  	if pkgpath := tools.gccgoCleanPkgpath(b, p); pkgpath != "" {
   552  		defs = append(defs, `-D`, `GOPKGPATH="`+pkgpath+`"`)
   553  	}
   554  	compiler := envList("CC", cfg.DefaultCC(cfg.Goos, cfg.Goarch))
   555  	if b.gccSupportsFlag(compiler, "-fsplit-stack") {
   556  		defs = append(defs, "-fsplit-stack")
   557  	}
   558  	defs = tools.maybePIC(defs)
   559  	if b.gccSupportsFlag(compiler, "-ffile-prefix-map=a=b") {
   560  		defs = append(defs, "-ffile-prefix-map="+base.Cwd()+"=.")
   561  		defs = append(defs, "-ffile-prefix-map="+b.WorkDir+"=/tmp/go-build")
   562  	} else if b.gccSupportsFlag(compiler, "-fdebug-prefix-map=a=b") {
   563  		defs = append(defs, "-fdebug-prefix-map="+b.WorkDir+"=/tmp/go-build")
   564  	}
   565  	if b.gccSupportsFlag(compiler, "-gno-record-gcc-switches") {
   566  		defs = append(defs, "-gno-record-gcc-switches")
   567  	}
   568  	return b.Shell(a).run(p.Dir, p.ImportPath, nil, compiler, "-Wall", "-g",
   569  		"-I", a.Objdir, "-I", inc, "-o", ofile, defs, "-c", cfile)
   570  }
   571  
   572  // maybePIC adds -fPIC to the list of arguments if needed.
   573  func (tools gccgoToolchain) maybePIC(args []string) []string {
   574  	switch cfg.BuildBuildmode {
   575  	case "c-shared", "shared", "plugin":
   576  		args = append(args, "-fPIC")
   577  	}
   578  	return args
   579  }
   580  
   581  func gccgoPkgpath(p *load.Package) string {
   582  	if p.Internal.Build.IsCommand() && !p.Internal.ForceLibrary {
   583  		return ""
   584  	}
   585  	return p.ImportPath
   586  }
   587  
   588  var gccgoToSymbolFuncOnce sync.Once
   589  var gccgoToSymbolFunc func(string) string
   590  
   591  func (tools gccgoToolchain) gccgoCleanPkgpath(b *Builder, p *load.Package) string {
   592  	gccgoToSymbolFuncOnce.Do(func() {
   593  		tmpdir := b.WorkDir
   594  		if cfg.BuildN {
   595  			tmpdir = os.TempDir()
   596  		}
   597  		fn, err := pkgpath.ToSymbolFunc(tools.compiler(), tmpdir)
   598  		if err != nil {
   599  			fmt.Fprintf(os.Stderr, "cmd/go: %v\n", err)
   600  			base.SetExitStatus(2)
   601  			base.Exit()
   602  		}
   603  		gccgoToSymbolFunc = fn
   604  	})
   605  
   606  	return gccgoToSymbolFunc(gccgoPkgpath(p))
   607  }
   608  
   609  var (
   610  	gccgoSupportsCgoIncompleteOnce sync.Once
   611  	gccgoSupportsCgoIncomplete     bool
   612  )
   613  
   614  const gccgoSupportsCgoIncompleteCode = `
   615  package p
   616  
   617  import "runtime/cgo"
   618  
   619  type I cgo.Incomplete
   620  `
   621  
   622  // supportsCgoIncomplete reports whether the gccgo/GoLLVM compiler
   623  // being used supports cgo.Incomplete, which was added in GCC 13.
   624  //
   625  // This takes an Action only for output reporting purposes.
   626  // The result value is unrelated to the Action.
   627  func (tools gccgoToolchain) supportsCgoIncomplete(b *Builder, a *Action) bool {
   628  	gccgoSupportsCgoIncompleteOnce.Do(func() {
   629  		sh := b.Shell(a)
   630  
   631  		fail := func(err error) {
   632  			fmt.Fprintf(os.Stderr, "cmd/go: %v\n", err)
   633  			base.SetExitStatus(2)
   634  			base.Exit()
   635  		}
   636  
   637  		tmpdir := b.WorkDir
   638  		if cfg.BuildN {
   639  			tmpdir = os.TempDir()
   640  		}
   641  		f, err := os.CreateTemp(tmpdir, "*_gccgo_cgoincomplete.go")
   642  		if err != nil {
   643  			fail(err)
   644  		}
   645  		fn := f.Name()
   646  		f.Close()
   647  		defer os.Remove(fn)
   648  
   649  		if err := os.WriteFile(fn, []byte(gccgoSupportsCgoIncompleteCode), 0644); err != nil {
   650  			fail(err)
   651  		}
   652  
   653  		on := strings.TrimSuffix(fn, ".go") + ".o"
   654  		if cfg.BuildN || cfg.BuildX {
   655  			sh.ShowCmd(tmpdir, "%s -c -o %s %s || true", tools.compiler(), on, fn)
   656  			// Since this function affects later builds,
   657  			// and only generates temporary files,
   658  			// we run the command even with -n.
   659  		}
   660  		cmd := exec.Command(tools.compiler(), "-c", "-o", on, fn)
   661  		cmd.Dir = tmpdir
   662  		var buf bytes.Buffer
   663  		cmd.Stdout = &buf
   664  		cmd.Stderr = &buf
   665  		err = cmd.Run()
   666  		gccgoSupportsCgoIncomplete = err == nil
   667  		if cfg.BuildN || cfg.BuildX {
   668  			// Show output. We always pass a nil err because errors are an
   669  			// expected outcome in this case.
   670  			desc := sh.fmtCmd(tmpdir, "%s -c -o %s %s", tools.compiler(), on, fn)
   671  			sh.reportCmd(desc, tmpdir, buf.Bytes(), nil)
   672  		}
   673  	})
   674  	return gccgoSupportsCgoIncomplete
   675  }
   676
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