}
	if c.Err != nil {
		fmt.Fprintf(b, ": %v", c.UnwrapModuleError())
	}
	return b.String()
}

// tidyRoots trims the root dependencies to the minimal requirements needed to
// both retain the same versions of all packages in pkgs and satisfy the
// graph-pruning invariants (if applicable).
func tidyRoots(ctx context.Context, rs *Requirements, pkgs []*loadPkg) (*Requirements, error) {

	}
	ld.exitIfErrors(ctx)

	// Tidy the build list, if applicable, before we report errors.
	// (The process of tidying may remove errors from irrelevant dependencies.)
	if ld.Tidy {
		rs, err := tidyRoots(ctx, ld.requirements, ld.pkgs)
		if err != nil {
			ld.error(err)
		} else {
			if ld.TidyGoVersion != "" {
				// Attempt to switch to the requested Go version. We have been using its