if offset >= len(src) {
		return end
	}
	if width := bytes.IndexAny(src[offset:], " \n,():;[]+-*"); width > 0 {
		end = start + token.Pos(width)
	}
	return end
}

func ZeroValue(f *ast.File, pkg *types.Package, typ types.Type) ast.Expr {
	// TODO(adonovan): think about generics, and also generic aliases.
	under := aliases.Unalias(typ)
	// Don't call Underlying unconditionally: although it removes

	c.warmupInputLeft = c.warmupInputCount

	if len(c.corpus.entries) == 0 {
		fmt.Fprintf(c.opts.Log, "warning: starting with empty corpus\n")
		var vals []any
		for _, t := range opts.Types {
			vals = append(vals, zeroValue(t))
		}
		data := marshalCorpusFile(vals...)
		h := sha256.Sum256(data)
		name := fmt.Sprintf("%x", h[:4])
		c.addCorpusEntries(false, CorpusEntry{Path: name, Data: data})
	}

	return c, nil
}