| <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="Explicit-Reg-Vars.html#Explicit-Reg-Vars" title="Explicit Reg Vars"> |
| <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, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, |
| 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, |
| 2008 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 1.2 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> |
| <link rel="stylesheet" type="text/css" href="../cs.css"> |
| </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="Explicit-Reg-Vars.html#Explicit-Reg-Vars">Explicit Reg Vars</a>, |
| Up: <a rel="up" accesskey="u" href="C-Extensions.html#C-Extensions">C Extensions</a> |
| <hr> |
| </div> |
| |
| <h3 class="section">6.43 Alternate Keywords</h3> |
| |
| <p><a name="index-alternate-keywords-2601"></a><a name="index-keywords_002c-alternate-2602"></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>). 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>) 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-2603"></a><a name="index-pedantic-2604"></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> |
| |
