p.FFiles = pp.FFiles
	p.SFiles = pp.SFiles
	p.SwigFiles = pp.SwigFiles
	p.SwigCXXFiles = pp.SwigCXXFiles
	p.SysoFiles = pp.SysoFiles
	if cfg.BuildMSan {
		// There's no way for .syso files to be built both with and without
		// support for memory sanitizer. Assume they are built without,
		// and drop them.
		p.SysoFiles = nil
	}
	p.CgoCFLAGS = pp.CgoCFLAGS
	p.CgoCPPFLAGS = pp.CgoCPPFLAGS
	p.CgoCXXFLAGS = pp.CgoCXXFLAGS

	// pieces supplied behind-the-scenes by package runtime.
	extFiles := len(p.CgoFiles) + len(p.CFiles) + len(p.CXXFiles) + len(p.MFiles) + len(p.FFiles) + len(p.SFiles) + len(p.SysoFiles) + len(p.SwigFiles) + len(p.SwigCXXFiles)
	if p.Standard {
		switch p.ImportPath {
		case "bytes", "internal/poll", "net", "os":
			fallthrough
		case "runtime/metrics", "runtime/pprof", "runtime/trace":
			fallthrough

	tg.setenv("CGO_ENABLED", "1")
	tg.run("list", "-f", "{{.SysoFiles}}", "syso")
	tg.grepStdout("a.syso", "missing syso file with CGO_ENABLED=1")

	tg.setenv("CGO_ENABLED", "0")
	tg.run("list", "-f", "{{.SysoFiles}}", "syso")
	tg.grepStdout("a.syso", "missing syso file with CGO_ENABLED=0")

	tg.setenv("CGO_ENABLED", "1")
	tg.run("list", "-msan", "-f", "{{.SysoFiles}}", "syso")

		return &p.FFiles
	case ".s", ".S", ".sx":
		return &p.SFiles
	case ".swig":
		return &p.SwigFiles
	case ".swigcxx":
		return &p.SwigCXXFiles
	case ".syso":
		return &p.SysoFiles
	}
	return nil
}

var errNoModules = errors.New("not using modules")

func findImportComment(data []byte) (s string, line int) {
	// expect keyword package
	word, data := parseWord(data)

	FFiles            []string // .f, .F, .for and .f90 Fortran source files
	SFiles            []string // .s source files
	SwigFiles         []string // .swig files
	SwigCXXFiles      []string // .swigcxx files
	SysoFiles         []string // .syso system object files to add to archive

	// Cgo directives
	CgoCFLAGS    []string // Cgo CFLAGS directives
	CgoCPPFLAGS  []string // Cgo CPPFLAGS directives

        SFiles            []string   // .s source files
        SwigFiles         []string   // .swig files
        SwigCXXFiles      []string   // .swigcxx files
        SysoFiles         []string   // .syso object files to add to archive
        TestGoFiles       []string   // _test.go files in package
        XTestGoFiles      []string   // _test.go files outside package

        // Embedded files

		}
	}

	// Input files.
	inputFiles := str.StringList(
		p.GoFiles,
		p.CgoFiles,
		p.CFiles,
		p.CXXFiles,
		p.FFiles,
		p.MFiles,
		p.HFiles,
		p.SFiles,
		p.SysoFiles,
		p.SwigFiles,
		p.SwigCXXFiles,
		p.EmbedFiles,
	)
	for _, file := range inputFiles {
		fmt.Fprintf(h, "file %s %s\n", file, b.fileHash(filepath.Join(p.Dir, file)))
	}
	for _, a1 := range a.Deps {

//	    SFiles            []string   // .s source files
//	    SwigFiles         []string   // .swig files
//	    SwigCXXFiles      []string   // .swigcxx files
//	    SysoFiles         []string   // .syso object files to add to archive
//	    TestGoFiles       []string   // _test.go files in package
//	    XTestGoFiles      []string   // _test.go files outside package
//
//	    // Embedded files

		{"Package.Root", Field, 0},
		{"Package.SFiles", Field, 0},
		{"Package.SrcRoot", Field, 0},
		{"Package.SwigCXXFiles", Field, 1},
		{"Package.SwigFiles", Field, 1},
		{"Package.SysoFiles", Field, 0},
		{"Package.TestDirectives", Field, 21},
		{"Package.TestEmbedPatternPos", Field, 16},
		{"Package.TestEmbedPatterns", Field, 16},
		{"Package.TestGoFiles", Field, 0},

pkg go/build, type Package struct, Root string
pkg go/build, type Package struct, SFiles []string
pkg go/build, type Package struct, SrcRoot string
pkg go/build, type Package struct, SysoFiles []string
pkg go/build, type Package struct, TestGoFiles []string
pkg go/build, type Package struct, TestImportPos map[string][]token.Position
pkg go/build, type Package struct, TestImports []string