1<html lang="en"> 2<head> 3<title>Fixed Headers - Using the GNU Compiler Collection (GCC)</title> 4<meta http-equiv="Content-Type" content="text/html"> 5<meta name="description" content="Using the GNU Compiler Collection (GCC)"> 6<meta name="generator" content="makeinfo 4.13"> 7<link title="Top" rel="start" href="index.html#Top"> 8<link rel="up" href="Trouble.html#Trouble" title="Trouble"> 9<link rel="prev" href="Incompatibilities.html#Incompatibilities" title="Incompatibilities"> 10<link rel="next" href="Standard-Libraries.html#Standard-Libraries" title="Standard Libraries"> 11<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 12<!-- 13Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 141998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 152010 Free Software Foundation, Inc. 16 17Permission is granted to copy, distribute and/or modify this document 18under the terms of the GNU Free Documentation License, Version 1.3 or 19any later version published by the Free Software Foundation; with the 20Invariant Sections being ``Funding Free Software'', the Front-Cover 21Texts being (a) (see below), and with the Back-Cover Texts being (b) 22(see below). A copy of the license is included in the section entitled 23``GNU Free Documentation License''. 24 25(a) The FSF's Front-Cover Text is: 26 27 A GNU Manual 28 29(b) The FSF's Back-Cover Text is: 30 31 You have freedom to copy and modify this GNU Manual, like GNU 32 software. Copies published by the Free Software Foundation raise 33 funds for GNU development.--> 34<meta http-equiv="Content-Style-Type" content="text/css"> 35<style type="text/css"><!-- 36 pre.display { font-family:inherit } 37 pre.format { font-family:inherit } 38 pre.smalldisplay { font-family:inherit; font-size:smaller } 39 pre.smallformat { font-family:inherit; font-size:smaller } 40 pre.smallexample { font-size:smaller } 41 pre.smalllisp { font-size:smaller } 42 span.sc { font-variant:small-caps } 43 span.roman { font-family:serif; font-weight:normal; } 44 span.sansserif { font-family:sans-serif; font-weight:normal; } 45--></style> 46<link rel="stylesheet" type="text/css" href="../cs.css"> 47</head> 48<body> 49<div class="node"> 50<a name="Fixed-Headers"></a> 51<p> 52Next: <a rel="next" accesskey="n" href="Standard-Libraries.html#Standard-Libraries">Standard Libraries</a>, 53Previous: <a rel="previous" accesskey="p" href="Incompatibilities.html#Incompatibilities">Incompatibilities</a>, 54Up: <a rel="up" accesskey="u" href="Trouble.html#Trouble">Trouble</a> 55<hr> 56</div> 57 58<h3 class="section">11.5 Fixed Header Files</h3> 59 60<p>GCC needs to install corrected versions of some system header files. 61This is because most target systems have some header files that won't 62work with GCC unless they are changed. Some have bugs, some are 63incompatible with ISO C, and some depend on special features of other 64compilers. 65 66 <p>Installing GCC automatically creates and installs the fixed header 67files, by running a program called <code>fixincludes</code>. Normally, you 68don't need to pay attention to this. But there are cases where it 69doesn't do the right thing automatically. 70 71 <ul> 72<li>If you update the system's header files, such as by installing a new 73system version, the fixed header files of GCC are not automatically 74updated. They can be updated using the <samp><span class="command">mkheaders</span></samp> script 75installed in 76<samp><var>libexecdir</var><span class="file">/gcc/</span><var>target</var><span class="file">/</span><var>version</var><span class="file">/install-tools/</span></samp>. 77 78 <li>On some systems, header file directories contain 79machine-specific symbolic links in certain places. This makes it 80possible to share most of the header files among hosts running the 81same version of the system on different machine models. 82 83 <p>The programs that fix the header files do not understand this special 84way of using symbolic links; therefore, the directory of fixed header 85files is good only for the machine model used to build it. 86 87 <p>It is possible to make separate sets of fixed header files for the 88different machine models, and arrange a structure of symbolic links so 89as to use the proper set, but you'll have to do this by hand. 90</ul> 91 92 </body></html> 93 94