vendorReplaced  []module.Version          // all replaced modules; may or may not also contribute packages
	vendorVersion   map[string]string         // module path → selected version (if known)
	vendorPkgModule map[string]module.Version // package → containing module
	vendorMeta      map[module.Version]vendorMetadata
)

type vendorMetadata struct {
	Explicit    bool
	Replacement module.Version
	GoVersion   string
}

			if inVendorDir {
				readVendorList(vendorDir)
				// If vendorPkgModule does not contain an entry for path then it's probably either because
				// vendor/modules.txt does not exist or the user manually added directories to the vendor directory.
				// Go 1.23 and later require vendored packages to be present in modules.txt to be imported.
				_, ok := vendorPkgModule[path]

				if cfg.BuildMod != "vendor" {
					return "", fmt.Errorf("without -mod=vendor, directory %s has no package path", absDir)
				}

				readVendorList(VendorDir())
				if _, ok := vendorPkgModule[pkg]; !ok {
					return "", fmt.Errorf("directory %s is not a package listed in vendor/modules.txt", absDir)
				}
				return pkg, nil
			}

			mainModulePrefix := MainModules.PathPrefix(mainModule)