[Gnu-arch-users] practical diff-mode.el question

[Robert Anderson]

I am currently in the midst of a Merge From Hell (note to self:
maintain branch discipline).

diff-mode.el is a godsend, especially the hunk splitting capability. 
However, I am going blind trying to figure out why certain hunks don't
apply.  AFAICT one trailing space can cause a patch to fail to apply. 
This is very hard to track down without automation.

Is there a way to say "show me why this doesn't apply", i.e., a
difference of the expected regions for modification and what is
actually there?  It doesn't appear there's anything native in
diff-mode.el for this, but maybe someone has conjured up a trick or
hack for this.  It seems obvious enough that it's hard to believe
something like this doesn't already exist, or maybe I am missing an
obvious way to achieve it.

Thanks for any pointers.

Bob