153 lines
8.8 KiB
HTML
153 lines
8.8 KiB
HTML
|
<html lang="en">
|
||
|
|
<head>
|
||
|
|
<title>Debugging C Plus Plus - Debugging with GDB</title>
|
||
|
|
<meta http-equiv="Content-Type" content="text/html">
|
||
|
|
<meta name="description" content="Debugging with GDB">
|
||
|
|
<meta name="generator" content="makeinfo 4.13">
|
||
|
|
<link title="Top" rel="start" href="index.html#Top">
|
||
|
|
<link rel="up" href="C.html#C" title="C">
|
||
|
|
<link rel="prev" href="Debugging-C.html#Debugging-C" title="Debugging C">
|
||
|
|
<link rel="next" href="Decimal-Floating-Point.html#Decimal-Floating-Point" title="Decimal Floating Point">
|
||
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
||
|
|
<!--
|
||
|
|
Copyright (C) 1988-2019 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 ``Free Software'' and ``Free Software Needs
|
||
|
|
Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,''
|
||
|
|
and with the Back-Cover Texts as in (a) below.
|
||
|
|
|
||
|
|
(a) The FSF's Back-Cover Text is: ``You are free to copy and modify
|
||
|
|
this GNU Manual. Buying copies from GNU Press supports the FSF in
|
||
|
|
developing GNU and promoting software freedom.''
|
||
|
|
-->
|
||
|
|
<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="Debugging-C-Plus-Plus"></a>
|
||
|
|
<p>
|
||
|
|
Next: <a rel="next" accesskey="n" href="Decimal-Floating-Point.html#Decimal-Floating-Point">Decimal Floating Point</a>,
|
||
|
|
Previous: <a rel="previous" accesskey="p" href="Debugging-C.html#Debugging-C">Debugging C</a>,
|
||
|
|
Up: <a rel="up" accesskey="u" href="C.html#C">C</a>
|
||
|
|
<hr>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
<h5 class="subsubsection">15.4.1.7 <span class="sc">gdb</span> Features for C<tt>++</tt></h5>
|
||
|
|
|
||
|
|
<p><a name="index-commands-for-C_0040t_007b_002b_002b_007d-1002"></a>
|
||
|
|
Some <span class="sc">gdb</span> commands are particularly useful with C<tt>++</tt>, and some are
|
||
|
|
designed specifically for use with C<tt>++</tt>. Here is a summary:
|
||
|
|
|
||
|
|
|
||
|
|
<a name="index-break-in-overloaded-functions-1003"></a>
|
||
|
|
<dl><dt><span class="roman">breakpoint menus</span><dd>When you want a breakpoint in a function whose name is overloaded,
|
||
|
|
<span class="sc">gdb</span> has the capability to display a menu of possible breakpoint
|
||
|
|
locations to help you specify which function definition you want.
|
||
|
|
See <a href="Ambiguous-Expressions.html#Ambiguous-Expressions">Ambiguous Expressions</a>.
|
||
|
|
|
||
|
|
<p><a name="index-overloading-in-C_0040t_007b_002b_002b_007d-1004"></a><br><dt><code>rbreak </code><var>regex</var><dd>Setting breakpoints using regular expressions is helpful for setting
|
||
|
|
breakpoints on overloaded functions that are not members of any special
|
||
|
|
classes.
|
||
|
|
See <a href="Set-Breaks.html#Set-Breaks">Setting Breakpoints</a>.
|
||
|
|
|
||
|
|
<p><a name="index-C_0040t_007b_002b_002b_007d-exception-handling-1005"></a><br><dt><code>catch throw</code><dt><code>catch rethrow</code><dt><code>catch catch</code><dd>Debug C<tt>++</tt> exception handling using these commands. See <a href="Set-Catchpoints.html#Set-Catchpoints">Setting Catchpoints</a>.
|
||
|
|
|
||
|
|
<p><a name="index-inheritance-1006"></a><br><dt><code>ptype </code><var>typename</var><dd>Print inheritance relationships as well as other information for type
|
||
|
|
<var>typename</var>.
|
||
|
|
See <a href="Symbols.html#Symbols">Examining the Symbol Table</a>.
|
||
|
|
|
||
|
|
<br><dt><code>info vtbl </code><var>expression</var><code>.</code><dd>The <code>info vtbl</code> command can be used to display the virtual
|
||
|
|
method tables of the object computed by <var>expression</var>. This shows
|
||
|
|
one entry per virtual table; there may be multiple virtual tables when
|
||
|
|
multiple inheritance is in use.
|
||
|
|
|
||
|
|
<p><a name="index-C_0040t_007b_002b_002b_007d-demangling-1007"></a><br><dt><code>demangle </code><var>name</var><dd>Demangle <var>name</var>.
|
||
|
|
See <a href="Symbols.html#Symbols">Symbols</a>, for a more complete description of the <code>demangle</code> command.
|
||
|
|
|
||
|
|
<p><a name="index-C_0040t_007b_002b_002b_007d-symbol-display-1008"></a><br><dt><code>set print demangle</code><dt><code>show print demangle</code><dt><code>set print asm-demangle</code><dt><code>show print asm-demangle</code><dd>Control whether C<tt>++</tt> symbols display in their source form, both when
|
||
|
|
displaying code as C<tt>++</tt> source and when displaying disassemblies.
|
||
|
|
See <a href="Print-Settings.html#Print-Settings">Print Settings</a>.
|
||
|
|
|
||
|
|
<br><dt><code>set print object</code><dt><code>show print object</code><dd>Choose whether to print derived (actual) or declared types of objects.
|
||
|
|
See <a href="Print-Settings.html#Print-Settings">Print Settings</a>.
|
||
|
|
|
||
|
|
<br><dt><code>set print vtbl</code><dt><code>show print vtbl</code><dd>Control the format for printing virtual function tables.
|
||
|
|
See <a href="Print-Settings.html#Print-Settings">Print Settings</a>.
|
||
|
|
(The <code>vtbl</code> commands do not work on programs compiled with the HP
|
||
|
|
ANSI C<tt>++</tt> compiler (<code>aCC</code>).)
|
||
|
|
|
||
|
|
<p><a name="index-set-overload_002dresolution-1009"></a><a name="index-overloaded-functions_002c-overload-resolution-1010"></a><br><dt><code>set overload-resolution on</code><dd>Enable overload resolution for C<tt>++</tt> expression evaluation. The default
|
||
|
|
is on. For overloaded functions, <span class="sc">gdb</span> evaluates the arguments
|
||
|
|
and searches for a function whose signature matches the argument types,
|
||
|
|
using the standard C<tt>++</tt> conversion rules (see <a href="C-Plus-Plus-Expressions.html#C-Plus-Plus-Expressions">C<tt>++</tt> Expressions</a>, for details).
|
||
|
|
If it cannot find a match, it emits a message.
|
||
|
|
|
||
|
|
<br><dt><code>set overload-resolution off</code><dd>Disable overload resolution for C<tt>++</tt> expression evaluation. For
|
||
|
|
overloaded functions that are not class member functions, <span class="sc">gdb</span>
|
||
|
|
chooses the first function of the specified name that it finds in the
|
||
|
|
symbol table, whether or not its arguments are of the correct type. For
|
||
|
|
overloaded functions that are class member functions, <span class="sc">gdb</span>
|
||
|
|
searches for a function whose signature <em>exactly</em> matches the
|
||
|
|
argument types.
|
||
|
|
|
||
|
|
<p><a name="index-show-overload_002dresolution-1011"></a><br><dt><code>show overload-resolution</code><dd>Show the current setting of overload resolution.
|
||
|
|
|
||
|
|
<br><dt><span class="roman">Overloaded symbol names</span><dd>You can specify a particular definition of an overloaded symbol, using
|
||
|
|
the same notation that is used to declare such symbols in C<tt>++</tt>: type
|
||
|
|
<var>symbol</var><code>(</code><var>types</var><code>)</code> rather than just <var>symbol</var>. You can
|
||
|
|
also use the <span class="sc">gdb</span> command-line word completion facilities to list the
|
||
|
|
available choices, or to finish the type list for you.
|
||
|
|
See <a href="Completion.html#Completion">Command Completion</a>, for details on how to do this.
|
||
|
|
|
||
|
|
<br><dt><span class="roman">Breakpoints in functions with ABI tags</span><dd>
|
||
|
|
The GNU C<tt>++</tt> compiler introduced the notion of ABI “tags”, which
|
||
|
|
correspond to changes in the ABI of a type, function, or variable that
|
||
|
|
would not otherwise be reflected in a mangled name. See
|
||
|
|
<a href="https://developers.redhat.com/blog/2015/02/05/gcc5-and-the-c11-abi/">https://developers.redhat.com/blog/2015/02/05/gcc5-and-the-c11-abi/</a>
|
||
|
|
for more detail.
|
||
|
|
|
||
|
|
<p>The ABI tags are visible in C<tt>++</tt> demangled names. For example, a
|
||
|
|
function that returns a std::string:
|
||
|
|
|
||
|
|
<pre class="smallexample"> std::string function(int);
|
||
|
|
</pre>
|
||
|
|
<p class="noindent">when compiled for the C++11 ABI is marked with the <code>cxx11</code> ABI
|
||
|
|
tag, and <span class="sc">gdb</span> displays the symbol like this:
|
||
|
|
|
||
|
|
<pre class="smallexample"> function[abi:cxx11](int)
|
||
|
|
</pre>
|
||
|
|
<p>You can set a breakpoint on such functions simply as if they had no
|
||
|
|
tag. For example:
|
||
|
|
|
||
|
|
<pre class="smallexample"> (gdb) b function(int)
|
||
|
|
Breakpoint 2 at 0x40060d: file main.cc, line 10.
|
||
|
|
(gdb) info breakpoints
|
||
|
|
Num Type Disp Enb Address What
|
||
|
|
1 breakpoint keep y 0x0040060d in function[abi:cxx11](int)
|
||
|
|
at main.cc:10
|
||
|
|
</pre>
|
||
|
|
<p>On the rare occasion you need to disambiguate between different ABI
|
||
|
|
tags, you can do so by simply including the ABI tag in the function
|
||
|
|
name, like:
|
||
|
|
|
||
|
|
<pre class="smallexample"> (gdb) b ambiguous[abi:other_tag](int)
|
||
|
|
</pre>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
</body></html>
|
||
|
|
|