<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- 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. -->
<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
<head>
<title>GNU Compiler Collection (GCC) Internals: Troubleshooting</title>

<meta name="description" content="GNU Compiler Collection (GCC) Internals: Troubleshooting">
<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Troubleshooting">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link href="index.html#Top" rel="start" title="Top">
<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="Type-Information.html#Type-Information" rel="up" title="Type Information">
<link href="Plugins.html#Plugins" rel="next" title="Plugins">
<link href="Invoking-the-garbage-collector.html#Invoking-the-garbage-collector" rel="prev" title="Invoking the garbage collector">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.indentedblock {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
div.smalllisp {margin-left: 3.2em}
kbd {font-style:oblique}
pre.display {font-family: inherit}
pre.format {font-family: inherit}
pre.menu-comment {font-family: serif}
pre.menu-preformatted {font-family: serif}
pre.smalldisplay {font-family: inherit; font-size: smaller}
pre.smallexample {font-size: smaller}
pre.smallformat {font-family: inherit; font-size: smaller}
pre.smalllisp {font-size: smaller}
span.nocodebreak {white-space:nowrap}
span.nolinebreak {white-space:nowrap}
span.roman {font-family:serif; font-weight:normal}
span.sansserif {font-family:sans-serif; font-weight:normal}
ul.no-bullet {list-style: none}
-->
</style>


</head>

<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
<a name="Troubleshooting"></a>
<div class="header">
<p>
Previous: <a href="Invoking-the-garbage-collector.html#Invoking-the-garbage-collector" accesskey="p" rel="prev">Invoking the garbage collector</a>, Up: <a href="Type-Information.html#Type-Information" accesskey="u" rel="up">Type Information</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Troubleshooting-the-garbage-collector"></a>
<h3 class="section">22.7 Troubleshooting the garbage collector</h3>
<a name="index-garbage-collector_002c-troubleshooting"></a>

<p>With the current garbage collector implementation, most issues should
show up as GCC compilation errors.  Some of the most commonly
encountered issues are described below.
</p>
<ul>
<li> Gengtype does not produce allocators for a <code>GTY</code>-marked type.
Gengtype checks if there is at least one possible path from GC roots to
at least one instance of each type before outputting allocators.  If
there is no such path, the <code>GTY</code> markers will be ignored and no
allocators will be output.  Solve this by making sure that there exists
at least one such path.  If creating it is unfeasible or raises a &ldquo;code
smell&rdquo;, consider if you really must use GC for allocating such type.

</li><li> Link-time errors about undefined <code>gt_ggc_r_foo_bar</code> and
similarly-named symbols.  Check if your <samp>foo_bar</samp> source file has
<code>#include &quot;gt-foo_bar.h&quot;</code> as its very last line.

</li></ul>


</body>
</html>