From: Jeff Norden <norden.jeff@gmail.com>
To: 64133@debbugs.gnu.org
Subject: bug#64133: CC Mode 5.35.2 (C/*l); incorrect indentation for an arrays of structs.
Date: Sat, 17 Jun 2023 10:03:24 -0500 [thread overview]
Message-ID: <CAPbFCnkeeJLBa_EvUaGs1uGxkUjnxJBNdAbOhKNLYEtPaO+hKw@mail.gmail.com> (raw)
I've verified the following behavior with c-version 5.35.2 (emacs-29,
and emacs-30 from git) and with 5.35.1 (emacs 28.2).
Place the following text into a file with a ".c" extension, and load
it with "emacs -Q".
==========================================
#include <stdio.h>
struct three_ints {
int a, b, c;
};
int main () {
struct three_ints numbers[]= {
{0,1,2},
{3,4,5},
{6,7,8}
};
for (int i=0; i<numbers[2].a; i++) {
printf("ack ");
}
printf("\n");
}
==========================================
Move the cursor to the beginning of the line with {3,4,5} and press
<tab> to indent the line. It will be incorrectly indented 2 spaces
more than the previous line. Move to the next line, press <tab>,
and you'll see:
struct three_ints numbers[]= {
{0,1,2},
{3,4,5},
{6,7,8}
};
Just using <tab> to re-indent the lines will not change anything.
But, if you add or delete white-space before {0,1,2} or {3,4,5} and
press <tab>, it *may* fix things. It seems to depend on just what you
delete and where the cursor is. The pattern isn't clear to me.
Once fixed, you get:
struct three_ints numbers[]= {
{0,1,2},
{3,4,5},
{6,7,8}
};
At this point it is stable, and <tab> will work correctly. If you
restart c-mode with "M-x c-mode", the problem re-occurs.
This bug only seems to occur when a loop or similar construct occurs
after the array declaration/initialization. It doesn't need to
immediately follow, though.
When incorrectly indenting, "C-c C-s" shows 'defun-block-intro' syntax
for the {0,1,2} line, and 'substatement-open' for {3,4,5} and {4,5,6}.
Once it gets fixed, this changes to 'brace-list-intro' and
'brace-entry-open'.
==========================================
For a more "real world" example, start with the example program at the
end of the getopt_long(3) man page:
https://linux.die.net/man/3/getopt_long
and move the declaration of long_options[] from inside the while loop
to before it. (This makes long_options a global variable, instead of
local to the loop).
==========================================
I'm afraid I can't offer a patch or suggestion for a fix. My own
attempts at "parsing" the lisp in cc-engine.el come to an abrupt halt
when my brain receives an urgent "Warning! Meltdown imminent!"
message from my subconscious -- just kidding :-).
However, I did stumble upon the following in the comments for the
`c-inside-bracelist-p' function:
;; CONTAINING-SEXP is the buffer pos of the innermost containing
;; paren. NO IT ISN'T!!! [This function is badly designed, and
;; probably needs reformulating without its first argument, ...
Thanks,
-Jeff
----------------------------
If believing that "function is more important than form" and that "people
are more important than technology" makes me a Luddite, then so be it!
next reply other threads:[~2023-06-17 15:03 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-17 15:03 Jeff Norden [this message]
2023-06-17 15:14 ` bug#64133: CC Mode 5.35.2 (C/*l); incorrect indentation for an arrays of structs Eli Zaretskii
[not found] ` <CAPbFCnniiTyPQBmayZpRwS46--JW6ipmmLAzMterB5cK9NEXCA@mail.gmail.com>
2023-06-17 16:27 ` Eli Zaretskii
2023-06-17 17:36 ` Jeff Norden
2023-06-18 13:13 ` Alan Mackenzie
2023-06-18 16:10 ` Jeff Norden
2023-06-18 17:23 ` Jeff Norden
2023-06-19 11:46 ` Alan Mackenzie
2023-06-19 14:30 ` Jeff Norden
2023-06-21 10:39 ` Alan Mackenzie
2023-06-21 18:43 ` Jeff Norden
2023-06-27 20:19 ` Alan Mackenzie
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