dirname: move m4/dos.m4 functionality into lib/dosname.h m4/dos.m4 needs to go. It laboriously invokes the C compiler, and extracts symbols from it, puts them into config.h; but it's much easier to use the symbols directly. filename.h already does this, but it disagrees with dos.m4 in some respects. This patch introduces a different include file dosname.h that packages up dos.m4, and then later we can work on merging filename.h and dosname.h. Applications that need only the easy-to-configure symbols should consider including dosname.h rather than dirname.h. * NEWS: Mention incompatible changes. * m4/dos.m4: Remove. * lib/dosname.h, modules/dosname: New files. * lib/dirname.h (ISSLASH, FILE_SYSTEM_PREFIX_LEN): (FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE): (IS_ABSOLUTE_FILE_NAME, IS_RELATIVE_FILE_NAME): Move to lib/dosname.h. * lib/at-func.c, lib/at-func2.c, lib/openat.c, lib/savewd.c: Include dosname.h, not dirname.h. * lib/rmdir.c, lib/stat.c, lib/unlink.c, lib/unlinkat.c: Include dosname.h, for definitions of symbols like ISSLASH that used to be in config.h. * m4/dirname.m4 (gl_DIRNAME_LGPL): Do not require gl_AC_DOS. * m4/rmdir.m4 (gl_FUNC_RMDIR): Likewise. * m4/stat.m4 (gl_FUNC_STAT): Likewise. * m4/unlink.m4 (gl_FUNC_UNLINK): Likewise. * modules/dirname-lgpl (Files): Omit m4/dos.m4. * modules/rmdir (Files): Likewise. * modules/stat (Files): Likewise. * modules/unlink (Files): Likewise. * modules/dirname-lgpl (Depends-on): Add dosname. * modules/lstat (Depends-on): Likewise. * modules/openat (Depends-on): Likewise. * modules/rmdir (Depends-on): Likewise. * modules/savewd (Depends-on): Likewise. * modules/stat (Depends-on): Likewise. * modules/unlink (Depends-on): Likewise. * modules/openat (Depends-on): Remove dirname-lgpl. * modules/savewd (Depends-on): Likewise. * tests/test-dirname.c: Do not use removed symbols like FILE_SYSTEM_BACKSLASH_IS_FILE_NAME_SEPARATOR. Instead, use the remaining symbols, e.g., ISSLASH ('\\').

--- a/lib/savewd.c
+++ b/lib/savewd.c
@@ -31,7 +31,7 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
-#include "dirname.h"
+#include "dosname.h"
 #include "fcntl-safer.h"
 
 /* Save the working directory into *WD, if it hasn't been saved