Re: [handa@m17n.org: C indentation problem]

[Kenichi Handa <handa@m17n.org>]

In article <Pine.LNX.3.96.1060418211302.439V-100000@acm.acm>, Alan Mackenzie <acm@muc.de> writes:

> Sometime between Emacs 21 and Emacs 22 CVS, the indentation in the actual
> source code was changed from:

> Emacs 21 sources:
> #########################################################################
> DEFUN ("forward-char", Fforward_char, Sforward_char, 0, 1, "p",
>   "Move point right N characters (left if N is negative).\n\
> On reaching end of buffer, stop and signal error.")
>   (n)                         <======           indentation of 2 columns.
>      Lisp_Object n;           <======           indentation of 5 columns.
> #########################################################################

> to

> Emacs 22 sources:
> #########################################################################
> DEFUN ("forward-char", Fforward_char, Sforward_char, 0, 1, "p",
>        doc: /* Move point right N characters (left if N is negative).
> On reaching end of buffer, stop and signal error.  */)
>      (n)                      <======           indentation of 5 columns.
>      Lisp_Object n;           <======           indentation of 5 columns.
> #########################################################################

Ah!  Yes.  I personally prefer Emacs 21 style (perhaps just
because I used to it for long time).

> However, CC Mode 5.28 seems to me to indent like the Emacs 22 sources are
> indented, i.e. column 5, and 5.

> The problem here is there is no Right Thing to do, since a C macro can
> violate any syntactic rules.  Consecutive parenthesis pairs are uncommon
> in C.

Yes.   But, I noticed this:

If I have a function without declaring the return type, I
get this indentation (case1):

test (a)
int a;
{
}

But, if I put the return type, I get this correct
indentation (case2):

int
test (a)
     int a;
{
}

And, if I insert extra parenthesis after the line of
function name, I get this (case3):

int
test (a)
  (b)
     int a;
{
}

And, when I delete "void" line, I get this (case 4):

test (a)
(b)
int a;
{
}

Is the difference of case1 and case2 (or case3 and case4)
intentional?  Isn't the case1 bug?

Is the indentation of case3 ("(b)" is indented by 2-col)
intentional?

Is it difficult to treat case4 as the same way as case3?  If
that is possible, I think DEFUN case is solved because DEFUN
syntax is the same as case4.

> I suggest the following: a new lineup function,
> c-lineup-gnu-DEFUN-intro-cont which would be active only in GNU style,
> and would give the offset knr-argdecl-intro (i.e. 5) for the lines
> between DEFUN's closing paren and the function's opening brace.  This new
> function would be tried only if the existing c-lineup-topmost-intro-cont
> returns nil.

I have no idea how adequate that method is.

> Question:  Are there any other C macros, besides DEFUN, whose indentation
> is also broken at the moment?  (I do not know the C source at all well.)

All I noticed is the DEFUN case.

---
Kenichi Handa
handa@m17n.org