CODE_STYLE: mention return w/o parens, but sizeof with

tastes satisfied.

Our C code has a few style rules. Most of them are verified and upheld by the

`lib/checksrc.pl` script. Invoked with `make checksrc` or even by default by

the build system when built after `./configure --enable-debug` has been used.

"lib/checksrc.pl" script. Invoked with "make checksrc" or even by default by

the build system when built after "./configure --enable-debug" has been used.

It is normally not a problem for anyone to follow the guidelines, as you just

need to copy the style already used in the source code and there are no

## Comments

Since we write C89 code, `//` comments are not allowed. They weren't

introduced in the C standard until C99. We use only `/*` and `*/` comments:

Since we write C89 code, **//** comments are not allowed. They weren't

introduced in the C standard until C99. We use only **/* comments */**.

    /* this is a comment */

## 'else' on the following line

When adding an `else` clause to a conditional expression using braces, we add

it on a new line after the closing brace. Like this:

When adding an **else** clause to a conditional expression using braces, we

add it on a new line after the closing brace. Like this:

    if(age < 40) {

      /* clearly a youngster */

## Space around operators

Please use spaces on both sides of operators in C expressions.  Postfix `(),

[], ->, ., ++, --` and Unary `+, - !, ~, &` operators excluded they should

Please use spaces on both sides of operators in C expressions.  Postfix **(),

[], ->, ., ++, --** and Unary **+, - !, ~, &** operators excluded they should

have no space.

Examples:

    complement = ~bits;

    empty = (!*string) ? TRUE : FALSE;

## No parentheses for return values

We use the 'return' statement without extra parentheses around the value:

    int works(void)

    {

      return TRUE;

    }

## Parentheses for sizeof arguments

When using the sizeof operator in code, we prefer it to be written with

parentheses around its argument:

    int size = sizeof(int);

## Column alignment

Some statements cannot be completed on a single line because the line would

be too long, the statement too hard to read, or due to other style guidelines

Some statements cannot be completed on a single line because the line would be

too long, the statement too hard to read, or due to other style guidelines

above. In such a case the statement will span multiple lines.

If a continuation line is part of an expression or sub-expression then you

should align on the appropriate column so that it's easy to tell what part of

the statement it is. Operators should not start continuation lines. In other

cases follow the 2-space indent guideline. Here are some examples from libcurl:

cases follow the 2-space indent guideline. Here are some examples from

libcurl:

~~~c

    if(Curl_pipeline_wanted(handle->multi, CURLPIPE_HTTP1) &&

       (handle->set.httpversion != CURL_HTTP_VERSION_1_0) &&

       (handle->set.httpreq == HTTPREQ_GET ||

        handle->set.httpreq == HTTPREQ_HEAD))

      /* didn't ask for HTTP/1.0 and a GET or HEAD */

      return TRUE;

~~~

~~~c

  case CURLOPT_KEEP_SENDING_ON_ERROR:

    data->set.http_keep_sending_on_error = (0 != va_arg(param, long)) ?

                                           TRUE : FALSE;

    break;

~~~

If no parenthesis, use the default indent:

~~~c

    data->set.http_disable_hostname_check_before_authentication =

      (0 != va_arg(param, long)) ? TRUE : FALSE;

~~~

~~~c

Function invoke with an open parenthesis:

    if(option) {

      result = parse_login_details(option, strlen(option),

                                   (userp ? &user : NULL),

                                   (passwdp ? &passwd : NULL),

                                   NULL);

    }

~~~

~~~c

Align with the "current open" parenthesis:

    DEBUGF(infof(data, "Curl_pp_readresp_ %d bytes of trailing "

                 "server response left\n",

                 (int)clipamount));

~~~

## Platform dependent code

Use `#ifdef HAVE_FEATURE` to do conditional code. We avoid checking for

Use **#ifdef HAVE_FEATURE** to do conditional code. We avoid checking for

particular operating systems or hardware in the #ifdef lines. The HAVE_FEATURE

shall be generated by the configure script for unix-like systems and they are

hard-coded in the config-[system].h files for the others.

We also encourage use of macros/functions that possibly are empty or defined

to constants when libcurl is built without that feature, to make the code

seamless. Like this style where the `magic()` function works differently

seamless. Like this example where the **magic()** function works differently

depending on a build-time conditional:

    #ifdef HAVE_MAGIC