[PATCH][driver] Don't add suffix for non-files

[Tamar Christina via Gcc-patches]

Hi All,

This patch fixes an issue where on systems that are
HAVE_TARGET_EXECUTABLE_SUFFIX the driver calls convert_filename in order to
add the suffix to the filename.  However while it excludes `-` it doesn't
exclude the null device.  This patches changes the check to exclude anything
that is not a file by calling not_actual_file_p instead.

This also fixes a bug in not_actual_file_p which was accidentally testing
a the global variable output_file instead of the supplied argument.  This
hasn't been an issue so far because because not_actual_file_p was only used
on output_file till now.

This fixes the adding of an extension to the nul device which is against
the recommendations on msdn[0] and makes it harder for the next tool in line
to detect it.

Bootstrapped Regtested on x86_64-w64-mingw32 and no issues.
Did do a bootstrap on x86_64-pc-linux-gnu but no regtest as it's not a
HAVE_TARGET_EXECUTABLE_SUFFIX system.

[0] https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file

Ok for master? and backport to GCC 8, 9 and 10.

Thanks,
Tamar

gcc/ChangeLog:

        PR driver/97574
        * gcc.c (convert_filename): Don't add suffix to things that are
        not files.
        (not_actual_file_p): Use supplied argument.

-- 

diff --git a/gcc/gcc.c b/gcc/gcc.c
index cdf4d4f2403e6236ff0f33c4def95bc445a51dee..1dae98f81da8ce39ec27554d11904efafffaa2cb 100644
--- a/gcc/gcc.c
+++ b/gcc/gcc.c
@@ -3653,7 +3653,7 @@ convert_filename (const char *name, int do_exe ATTRIBUTE_UNUSED,
 #if defined(HAVE_TARGET_EXECUTABLE_SUFFIX)
   /* If there is no filetype, make it the executable suffix (which includes
      the ".").  But don't get confused if we have just "-o".  */
-  if (! do_exe || TARGET_EXECUTABLE_SUFFIX[0] == 0 || (len == 2 && name[0] == '-'))
+  if (! do_exe || TARGET_EXECUTABLE_SUFFIX[0] == 0 || not_actual_file_p (name))
     return name;
 
   for (i = len - 1; i >= 0; i--)
@@ -10544,7 +10544,7 @@ static bool
 not_actual_file_p (const char *name)
 {
   return (strcmp (name, "-") == 0
-	  || strcmp (output_file, HOST_BIT_BUCKET) == 0);
+	  || strcmp (name, HOST_BIT_BUCKET) == 0);
 }
 
 /* %:dumps spec function.  Take an optional argument that overrides