bug#17388: 24.4.50; REGRESSION: Ediff - 1) wrong face, 2) incorrect diffing

[Drew Adams]

1. A diff that is not the current one should use face
`ediff-(odd|even)-diff-(A|B').  This is now broken.

It does use that face for the main diff, but it still tries to show fine
differences within that diff - which is new.  That would be OK, I guess,
but it should not use face `default' to show such fine diffs.  It should
use an Ediff face, which users can customize without affecting other
things (as happens with `default').

Using face `default' here is particular misguided, as it suggests that
there is no difference at those locations, whereas there likely is.

See the attached screenshot.  The first diff shown, with the gray
highlighting, shows the regression.  


2. The fine diffs are also not correct.  See the same screenshot.  For
the first diff, "advertise" and "d-signature-table" should be
highlighted the same as "(defvar " and ")", and for the second diff,
"fil" and "s-alist" should be highlighted the same as "(defvar " and
")".  These are not differences.

I am using Cygwin `diff', which could affect #2 presumably.  But #2 is
still a regression wrt prior Emacs versions.  With Emacs 24.3, for
instance (using the same Cygwin `diff'), there is no fine diff shown
here.  Instead, the diff, which is shown only as a main diff, is between
"file-local-variables-alist" and "filxxxxxxxxxxxxxxxxxxxxxs-alist".
Which is correct.

Emacs should not show fine diffs that are are patently wrong.
Better not to mislead.



In GNU Emacs 24.4.50.1 (i686-pc-mingw32)
 of 2014-04-29 on ODIEONE
Bzr revision: 117031 monnier@iro.umontreal.ca-20140429151607-qnkgbymwfaj5ut08
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/Devel/emacs/snapshot/trunk
 --enable-checking=yes,glyphs 'CFLAGS=-O0 -g3'
 LDFLAGS=-Lc:/Devel/emacs/lib 'CPPFLAGS=-DGC_MCHECK=1
 -Ic:/Devel/emacs/include''

throw-emacs-bug-ediff.png
Description: PNG image