[Bug regression/80208] New: DJGPP max object file alignment regression

["gcc at pkh dot me" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80208

            Bug ID: 80208
           Summary: DJGPP max object file alignment regression
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: regression
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gcc at pkh dot me
  Target Milestone: ---

Using DJGPP, requested alignment is not clamped anymore:

[/tmp]☭ echo 'int __attribute__ ((aligned (16))) x;' > a.c &&
i686-pc-msdosdjgpp-cc -c a.c
[/tmp]☭ echo 'int __attribute__ ((aligned (32))) x;' > a.c &&
i686-pc-msdosdjgpp-cc -c a.c
a.c:1:36: error: alignment of ‘x’ is greater than maximum object file alignment
16
 int __attribute__ ((aligned (32))) x;
                                    ^
[/tmp]☠ 

This is a regression since r205040
(https://github.com/gcc-mirror/gcc/commit/f8f7421ff48c9a90a63281bb09ff67d4f56755cf).
We hit that issue in the FFmpeg project where such alignment is requested in
random places (because we sometimes have AVX2 optimizations, which shouldn't
concern a FreeDOS configuration).

Here is a simple patch that fixes the issue:

--- gcc/varasm.c        2017-03-26 20:10:03.082212374 +0200
+++ gcc/varasm.c        2017-03-26 20:10:00.079320606 +0200
@@ -1005,8 +1005,8 @@
   if (align > MAX_OFILE_ALIGNMENT)
     {
-      error ("alignment of %q+D is greater than maximum object "
+      warning (0, "alignment of %q+D is greater than maximum object "
             "file alignment %d", decl,
             MAX_OFILE_ALIGNMENT/BITS_PER_UNIT);
       align = MAX_OFILE_ALIGNMENT;
     }

The fallback to MAX_OFILE_ALIGNMENT is still present so it's enough to fix the
problem.