bug#12527: 24.2; idented preprocessor directives confusing cc-mode indent

[Kevin Burge <kcburge@gmail.com>]

Summary: Indenting the preprocessor blocks at least 1 space completely
throws off the cc-mode indentation for anything after the
preprocessor block.

To reproduce: Create the simple file "test.cpp":

===
int f(void) {
  #if defined(A)
  printf("test\n");
  #endif

  if (test) {
    int i = 0;
  }
}
===

IMPORTANT: "#if.....#endif" block MUST be indented at least 1 space.

If you navigate inside the "if (test)" block and hit tab, it
un-indents the line, and any lines after it, to the end of the file.
If you reindent the entire file, it works just fine, because the
indented preprocessor directives, which works around the problem.

You have to play around with this, too.  There are certain variations
of the #if line that affect the behavior.  And, each time you test,
you MUST re-open the file, because the caching seems to completely
throw it off.

I.e. if you change the #if block to

===
  #if 0
  printf("test\n");
  #endif
===

And re-load the file, then try to indent the "if (test)" block, it
does what it should.  Also, changing it to (and reloading):

===
  #if A
  printf("test\n");
  #endif
===

Is sufficient to break it again.  So, it seems like whatever follows
the #if affects the behavior.

Note: I ran with emacs -q, so, it's not processing any of my configuration.

I have hundreds of thousands of lines of codes that use indented
preprocessor directives, so making all those changes is not really an
option for us.

===========================

In GNU Emacs 24.2.1 (x86_64-unknown-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2012-09-27 on kevin
Windowing system distributor `CentOS', version 11.0.11006000
Configured using:
 `configure '--prefix=/usr/local/emacs24' '--with-x-toolkit=lucid''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: nil
  value of $XMODIFIERS: @im=none
  locale-coding-system: nil
  default enable-multibyte-characters: t

Major mode: C++/l

Minor modes in effect:
  tooltip-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t
  abbrev-mode: t

Recent input:
C-x C-f t e s t . c p <tab> <return> C-n <tab> C-n
C-/ C-n <tab> C-n <tab> C-/ C-x C-s C-n C-n C-a <tab>
C-n C-a <tab> C-n C-a <tab> <tab> <tab> <tab> C-p C-p
C-p C-p C-p C-p C-p C-p C-p C-SPC C-n C-n C-n C-n C-n
C-n C-n C-n C-n M-w <M-down-mouse-1> <mouse-movement>
<mouse-movement> <M-drag-mouse-1> M-x b u <backspace>
<backspace> r e p o r t - b u g <tab> <return>

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Undo! [2 times]
(No changes need to be saved)
byte-code: Beginning of buffer [2 times]
Mark set

Load-path shadows:
None found.

Features:
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