Re: [Qemu-devel] [PATCH] CODING_STYLE: don't allow non-indented statements after if/else blocks

[Blue Swirl <blauwirbel@gmail.com>]

On Mon, Oct 26, 2009 at 10:03 PM, Aurelien Jarno <aurelien@aurel32.net> wrote:
> On Mon, Oct 26, 2009 at 06:02:52PM +0200, Blue Swirl wrote:
>> On Mon, Oct 26, 2009 at 8:26 AM, Aurelien Jarno <aurelien@aurel32.net> wrote:
>> > Rationale: The following code is difficult to read, but allowed by the
>> > current coding style.
>>
>> Fully agree.
>>
>> > +Every control flow statement is followed by a new indented and braced
>> > +block; even if the block contains just one statement.  The opening brace
>> > +is on the line that contains the control flow statement that introduces
>> > +the new block; the closing brace is on the same line as the else keyword,
>> > +or on a line by itself if there is no else keyword.  Example:
>>
>> I think an exception should be granted for "else if" case, otherwise
>> the style would require braces around "if", like:
>>     if (a == 5) {
>>         printf("a was 5.\n");
>>     } else {
>>         if (a == 6) {
>>             printf("a was 6.\n");
>>         }
>>     } else {
>>         printf("a was something else entirely.\n");
>>     }
>>
>> Picking nits: "while" is a control flow statement, even in "do {}
>> while" statement and then it would illegal to require a braced block
>> after the "while" statement.
>
> Good point. Please find another try below:
>
> From: Aurelien Jarno <aurelien@aurel32.net>
>
> Rationale: The following code is difficult to read:
>
>    if (a == 5) printf("a was 5.\n");
>    else if (a == 6) printf("a was 6.\n");
>    else printf("a was something else entirely.\n");
>
> Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
> ---
>  CODING_STYLE |   12 +++++++-----
>  1 files changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/CODING_STYLE b/CODING_STYLE
> index a579cb1..c17c3f3 100644
> --- a/CODING_STYLE
> +++ b/CODING_STYLE
> @@ -51,11 +51,13 @@ QEMU coding style.
>
>  4. Block structure
>
> -Every indented statement is braced; even if the block contains just one
> -statement.  The opening brace is on the line that contains the control
> -flow statement that introduces the new block; the closing brace is on the
> -same line as the else keyword, or on a line by itself if there is no else
> -keyword.  Example:
> +Every control flow statement is followed by a new indented and braced
> +block, except if it is followed by another control flow statement (else
> +if) or by a condition (do {} while ()); even if the block contains just
> +one statement.  The opening brace is on the line that contains the
> +control flow statement that introduces the new block; the closing
> +brace is on the same line as the else keyword, or on a line by itself
> +if there is no else keyword.  Example:

Nice try, but does it prevent this:
    if (x) for (;;) do {
    } while (0);
?

Maybe also "break" and "goto" can be considered control flow statements.

How about something like "wherever C syntax allows potentially
ambiguous sequence of statements, braces must be used, with the
exception of 'else' followed by 'if'"? Now the problem becomes
defining ambiguous sequences of statements.