https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65852
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Here is what the comment says in the source: /* Given a filename, quote characters in that filename which are significant to Make. Note that it's not possible to quote all such characters - e.g. \n, %, *, ?, [, \ (in some contexts), and ~ are not properly handled. It isn't possible to get this right in any current version of Make. (??? Still true? Old comment referred to 3.76.1.) */ So maybe there was an issue with make at one point. Basically \ is not mungled to be what it should be done.
