// src/cmd/go/internal/modcmd/vendor.go
	fold := str.ToFold(p.ImportPath)
	if other := foldPath[fold]; other == "" {
		foldPath[fold] = p.ImportPath
	} else if other != p.ImportPath {
		setError(ImportErrorf(p.ImportPath, "case-insensitive import collision: %q and %q", p.ImportPath, other))
		return
	}

	if !SafeArg(p.ImportPath) {
		setError(ImportErrorf(p.ImportPath, "invalid import path %q", p.ImportPath))
		return
	}

		p1 := a1.Package
		if p1 == nil || p1.ImportPath == "" {
			continue
		}
		// Add import mapping if needed
		// (for imports like "runtime/cgo" that appear only in generated code).
		if !vcfgMapped[p1.ImportPath] {
			vcfg.ImportMap[p1.ImportPath] = p1.ImportPath
		}
		if a1.built != "" {
			vcfg.PackageFile[p1.ImportPath] = a1.built
		}
		if p1.Standard {

// syntax of package template. The default output is equivalent
// to -f '{{.ImportPath}}'. The struct being passed to the template is:
//
//	type Package struct {
//	    Dir            string   // directory containing package sources
//	    ImportPath     string   // import path of package in dir
//	    ImportComment  string   // path in import comment on package statement

of that package.
The import names an identifier (PackageName) to be used for access and an ImportPath
that specifies the package to be imported.
</p>

<pre class="ebnf">
ImportDecl       = "import" ( ImportSpec | "(" { ImportSpec ";" } ")" ) .
ImportSpec       = [ "." | PackageName ] ImportPath .
ImportPath       = string_lit .
</pre>

<p>

)

func addstrdata1(ctxt *Link, arg string) {
	eq := strings.Index(arg, "=")
	dot := strings.LastIndex(arg[:eq+1], ".")
	if eq < 0 || dot < 0 {
		Exitf("-X flag requires argument of the form importpath.name=value")
	}
	pkg := arg[:dot]
	if ctxt.BuildMode == BuildModePlugin && pkg == "main" {
		pkg = *flagPluginPath
	}
	pkg = objabi.PathToPrefix(pkg)
	name := pkg + arg[dot:eq]