You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
91 lines
4.6 KiB
HTML
91 lines
4.6 KiB
HTML
<html lang="en">
|
|
<head>
|
|
<title>Alternate Keywords - Using the GNU Compiler Collection (GCC)</title>
|
|
<meta http-equiv="Content-Type" content="text/html">
|
|
<meta name="description" content="Using the GNU Compiler Collection (GCC)">
|
|
<meta name="generator" content="makeinfo 4.13">
|
|
<link title="Top" rel="start" href="index.html#Top">
|
|
<link rel="up" href="C-Extensions.html#C-Extensions" title="C Extensions">
|
|
<link rel="prev" href="Using-Assembly-Language-with-C.html#Using-Assembly-Language-with-C" title="Using Assembly Language with C">
|
|
<link rel="next" href="Incomplete-Enums.html#Incomplete-Enums" title="Incomplete Enums">
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
|
<!--
|
|
Copyright (C) 1988-2015 Free Software Foundation, Inc.
|
|
|
|
Permission is granted to copy, distribute and/or modify this document
|
|
under the terms of the GNU Free Documentation License, Version 1.3 or
|
|
any later version published by the Free Software Foundation; with the
|
|
Invariant Sections being ``Funding Free Software'', the Front-Cover
|
|
Texts being (a) (see below), and with the Back-Cover Texts being (b)
|
|
(see below). A copy of the license is included in the section entitled
|
|
``GNU Free Documentation License''.
|
|
|
|
(a) The FSF's Front-Cover Text is:
|
|
|
|
A GNU Manual
|
|
|
|
(b) The FSF's Back-Cover Text is:
|
|
|
|
You have freedom to copy and modify this GNU Manual, like GNU
|
|
software. Copies published by the Free Software Foundation raise
|
|
funds for GNU development.-->
|
|
<meta http-equiv="Content-Style-Type" content="text/css">
|
|
<style type="text/css"><!--
|
|
pre.display { font-family:inherit }
|
|
pre.format { font-family:inherit }
|
|
pre.smalldisplay { font-family:inherit; font-size:smaller }
|
|
pre.smallformat { font-family:inherit; font-size:smaller }
|
|
pre.smallexample { font-size:smaller }
|
|
pre.smalllisp { font-size:smaller }
|
|
span.sc { font-variant:small-caps }
|
|
span.roman { font-family:serif; font-weight:normal; }
|
|
span.sansserif { font-family:sans-serif; font-weight:normal; }
|
|
--></style>
|
|
</head>
|
|
<body>
|
|
<div class="node">
|
|
<a name="Alternate-Keywords"></a>
|
|
<p>
|
|
Next: <a rel="next" accesskey="n" href="Incomplete-Enums.html#Incomplete-Enums">Incomplete Enums</a>,
|
|
Previous: <a rel="previous" accesskey="p" href="Using-Assembly-Language-with-C.html#Using-Assembly-Language-with-C">Using Assembly Language with C</a>,
|
|
Up: <a rel="up" accesskey="u" href="C-Extensions.html#C-Extensions">C Extensions</a>
|
|
<hr>
|
|
</div>
|
|
|
|
<h3 class="section">6.44 Alternate Keywords</h3>
|
|
|
|
<p><a name="index-alternate-keywords-3507"></a><a name="index-keywords_002c-alternate-3508"></a>
|
|
<samp><span class="option">-ansi</span></samp> and the various <samp><span class="option">-std</span></samp> options disable certain
|
|
keywords. This causes trouble when you want to use GNU C extensions, or
|
|
a general-purpose header file that should be usable by all programs,
|
|
including ISO C programs. The keywords <code>asm</code>, <code>typeof</code> and
|
|
<code>inline</code> are not available in programs compiled with
|
|
<samp><span class="option">-ansi</span></samp> or <samp><span class="option">-std</span></samp> (although <code>inline</code> can be used in a
|
|
program compiled with <samp><span class="option">-std=c99</span></samp> or <samp><span class="option">-std=c11</span></samp>). The
|
|
ISO C99 keyword
|
|
<code>restrict</code> is only available when <samp><span class="option">-std=gnu99</span></samp> (which will
|
|
eventually be the default) or <samp><span class="option">-std=c99</span></samp> (or the equivalent
|
|
<samp><span class="option">-std=iso9899:1999</span></samp>), or an option for a later standard
|
|
version, is used.
|
|
|
|
<p>The way to solve these problems is to put ‘<samp><span class="samp">__</span></samp>’ at the beginning and
|
|
end of each problematical keyword. For example, use <code>__asm__</code>
|
|
instead of <code>asm</code>, and <code>__inline__</code> instead of <code>inline</code>.
|
|
|
|
<p>Other C compilers won't accept these alternative keywords; if you want to
|
|
compile with another compiler, you can define the alternate keywords as
|
|
macros to replace them with the customary keywords. It looks like this:
|
|
|
|
<pre class="smallexample"> #ifndef __GNUC__
|
|
#define __asm__ asm
|
|
#endif
|
|
</pre>
|
|
<p><a name="index-g_t_005f_005fextension_005f_005f-3509"></a><a name="index-pedantic-3510"></a><samp><span class="option">-pedantic</span></samp> and other options cause warnings for many GNU C extensions.
|
|
You can
|
|
prevent such warnings within one expression by writing
|
|
<code>__extension__</code> before the expression. <code>__extension__</code> has no
|
|
effect aside from this.
|
|
|
|
</body></html>
|
|
|