On Fri, 12 Feb 2021 at 14:45, Dave Chinner [off-list ref] wrote:

So there's a rule like this generated:

bitmap.lo: bitmap.c ../include/xfs.h ../include/xfs/linux.h \
 ../include/xfs/xfs_types.h ../include/xfs/xfs_fs_compat.h \
 ../include/xfs/xfs_fs.h ../include/platform_defs.h avl64.h \
 ../include/list.h bitmap.h

The sed expression is:

$(SED) -e 's,^\([^:]*\)\.o,\1.lo,'

Which means it is supposed to match from the start of line to a ".o",
and store everything up to the ".o" in register 1.

And the problem is that it is matching a ".o" in the middle of a
string.

So existing behaviour:

$ echo "foo.o/bitmap.o: bitmap.c ../include/xfs.h ../include/xfs/linux.h" | sed -e 's,^\([^:]*\)\.o,\1.lo,'
foo.o/bitmap.lo: bitmap.c ../include/xfs.h ../include/xfs/linux.h
$

Looks correct until the dependency line is split and the first entry
in the split line is something like "foo.o/uuid.h"

Your modified version:

$ echo "bitmap.o: bitmap.c ../include/xfs.h ../include/xfs/linux.h" | sed -e 's,^\([^:]*\)\.o$$,\1.lo,'
bitmap.o: bitmap.c ../include/xfs.h ../include/xfs/linux.h
$

Doesn't work for the case we actually need the substitution for.

So, really, I think we need to match against the full target
specification rather than just ".o".

Something like

$SED -e 's,^\([^:]*\)\.o: ,\1.lo: ,'

$ echo "foo.o/bitmap: bitmap.c ../include/xfs.h ../include/xfs/linux.h" | sed -e 's,^\([^:]*\)\.o: ,\1.lo: ,'
foo.o/bitmap: bitmap.c ../include/xfs.h ../include/xfs/linux.h
$ echo "foo.o/bitmap.o: bitmap.c ../include/xfs.h ../include/xfs/linux.h" | sed -e 's,^\([^:]*\)\.o: ,\1.lo: ,'
foo.o/bitmap.lo: bitmap.c ../include/xfs.h ../include/xfs/linux.h

Thanks. I just tried your suggestion. Looks like it's working for my
situation. I'll submit a v2 of the patch.

Regards,
-Markus