bug#27402: 26.0.50; Indentation regression for C99 struct initializers

[Adam Niederer]

Hello, I believe I've found a regression in c-mode's indentation.

Start emacs, create a buffer in c-mode, paste the following code snippet
in, and press C-x h TAB to autoindent the buffer.

void main() {
  struct Foo foo = {
    .a = 2,
    .b = 3
  };
}

Emacs 25.2 indents the code as seen above, whereas Emacs 26.0.50 indents
it as such:

void main() {
  struct Foo foo = {
                    .a = 2,
                    .b = 3
  };
}

The debug information within this message is from the build of Emacs
26.0.50 which exhibits the incorrect indentation behavior.

-Adam



In GNU Emacs 26.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.15)
of 2017-06-17 built on AdamsPC
Repository revision: 49c0ff29c2e0243ba35ec17e3e3af49369be43db
Windowing system distributor 'The X.Org Foundation', version 11.0.11903000
System Description: Arch Linux

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Mark set [2 times]
Indenting region... done
Mark set
Mark deactivated

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GCONF GSETTINGS
NOTIFY ACL GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 LIBSYSTEMD

Important settings:
value of $LC_COLLATE: en_US.UTF-8
value of $LANG: en_US.UTF-8
locale-coding-system: utf-8-unix

Major mode: C/*l

Minor modes in effect:
tooltip-mode: t
global-eldoc-mode: t
electric-indent-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

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message subr-x puny seq byte-opt
bytecomp byte-compile cconv dired dired-loaddefs format-spec rfc822 mml
mml-sec password-cache epa derived epg epg-config gnus-util rmail
rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums
mm-util mail-prsvr mail-utils cc-mode cc-fonts easymenu cc-guess
cc-menus cc-cmds cc-styles cc-align cc-engine cc-vars cc-defs cl gv
cl-loaddefs cl-lib time-date mule-util tooltip eldoc electric uniquify
ediff-hook vc-hooks lisp-float-type mwheel term/x-win x-win
term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode elisp-mode lisp-mode
prog-mode register page menu-bar rfn-eshadow isearch timer select
scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame cl-generic cham georgian utf-8-lang misc-lang
vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms cp51932
hebrew greek romanian slovak czech european ethiopic indian cyrillic
chinese composite charscript charprop case-table epa-hook jka-cmpr-hook
help simple abbrev obarray minibuffer cl-preloaded nadvice loaddefs
button faces cus-face macroexp files text-properties overlay sha1 md5
base64 format env code-pages mule custom widget hashtable-print-readable
backquote dbusbind inotify dynamic-setting system-font-setting
font-render-setting move-toolbar gtk x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 16 114550 7062)
(symbols 48 22532 1)
(miscs 40 53 190)
(strings 32 23459 3790)
(string-bytes 1 843862)
(vectors 16 16328)
(vector-slots 8 503209 4719)
(floats 8 49 67)
(intervals 56 260 0)
(buffers 976 12))