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diff --git a/share/doc/gdb/Ambiguous-Expressions.html b/share/doc/gdb/Ambiguous-Expressions.html new file mode 100644 index 0000000..38ee053 --- /dev/null +++ b/share/doc/gdb/Ambiguous-Expressions.html @@ -0,0 +1,162 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1988-2023 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." --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>Debugging with GDB: Ambiguous Expressions</title> + +<meta name="description" content="Debugging with GDB: Ambiguous Expressions"> +<meta name="keywords" content="Debugging with GDB: Ambiguous Expressions"> +<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="Concept-Index.html#Concept-Index" rel="index" title="Concept Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Data.html#Data" rel="up" title="Data"> +<link href="Variables.html#Variables" rel="next" title="Variables"> +<link href="Expressions.html#Expressions" rel="previous" title="Expressions"> +<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="Ambiguous-Expressions"></a> +<div class="header"> +<p> +Next: <a href="Variables.html#Variables" accesskey="n" rel="next">Variables</a>, Previous: <a href="Expressions.html#Expressions" accesskey="p" rel="previous">Expressions</a>, Up: <a href="Data.html#Data" accesskey="u" rel="up">Data</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="Ambiguous-Expressions-1"></a> +<h3 class="section">10.2 Ambiguous Expressions</h3> +<a name="index-ambiguous-expressions"></a> + +<p>Expressions can sometimes contain some ambiguous elements. For instance, +some programming languages (notably Ada, C<tt>++</tt> and Objective-C) permit +a single function name to be defined several times, for application in +different contexts. This is called <em>overloading</em>. Another example +involving Ada is generics. A <em>generic package</em> is similar to C<tt>++</tt> +templates and is typically instantiated several times, resulting in +the same function name being defined in different contexts. +</p> +<p>In some cases and depending on the language, it is possible to adjust +the expression to remove the ambiguity. For instance in C<tt>++</tt>, you +can specify the signature of the function you want to break on, as in +<kbd>break <var>function</var>(<var>types</var>)</kbd>. In Ada, using the fully +qualified name of your function often makes the expression unambiguous +as well. +</p> +<p>When an ambiguity that needs to be resolved is detected, the debugger +has the capability to display a menu of numbered choices for each +possibility, and then waits for the selection with the prompt ‘<samp>></samp>’. +The first option is always ‘<samp>[0] cancel</samp>’, and typing <kbd>0 <span class="key">RET</span></kbd> +aborts the current command. If the command in which the expression was +used allows more than one choice to be selected, the next option in the +menu is ‘<samp>[1] all</samp>’, and typing <kbd>1 <span class="key">RET</span></kbd> selects all possible +choices. +</p> +<p>For example, the following session excerpt shows an attempt to set a +breakpoint at the overloaded symbol <code>String::after</code>. +We choose three particular definitions of that function name: +</p> +<div class="smallexample"> +<pre class="smallexample">(gdb) b String::after +[0] cancel +[1] all +[2] file:String.cc; line number:867 +[3] file:String.cc; line number:860 +[4] file:String.cc; line number:875 +[5] file:String.cc; line number:853 +[6] file:String.cc; line number:846 +[7] file:String.cc; line number:735 +> 2 4 6 +Breakpoint 1 at 0xb26c: file String.cc, line 867. +Breakpoint 2 at 0xb344: file String.cc, line 875. +Breakpoint 3 at 0xafcc: file String.cc, line 846. +Multiple breakpoints were set. +Use the "delete" command to delete unwanted + breakpoints. +(gdb) +</pre></div> + +<dl compact="compact"> +<dd><a name="index-set-multiple_002dsymbols"></a> +</dd> +<dt><code>set multiple-symbols <var>mode</var></code></dt> +<dd><a name="index-multiple_002dsymbols-menu"></a> + +<p>This option allows you to adjust the debugger behavior when an expression +is ambiguous. +</p> +<p>By default, <var>mode</var> is set to <code>all</code>. If the command with which +the expression is used allows more than one choice, then <small>GDB</small> +automatically selects all possible choices. For instance, inserting +a breakpoint on a function using an ambiguous name results in a breakpoint +inserted on each possible match. However, if a unique choice must be made, +then <small>GDB</small> uses the menu to help you disambiguate the expression. +For instance, printing the address of an overloaded function will result +in the use of the menu. +</p> +<p>When <var>mode</var> is set to <code>ask</code>, the debugger always uses the menu +when an ambiguity is detected. +</p> +<p>Finally, when <var>mode</var> is set to <code>cancel</code>, the debugger reports +an error due to the ambiguity and the command is aborted. +</p> +<a name="index-show-multiple_002dsymbols"></a> +</dd> +<dt><code>show multiple-symbols</code></dt> +<dd><p>Show the current value of the <code>multiple-symbols</code> setting. +</p></dd> +</dl> + +<hr> +<div class="header"> +<p> +Next: <a href="Variables.html#Variables" accesskey="n" rel="next">Variables</a>, Previous: <a href="Expressions.html#Expressions" accesskey="p" rel="previous">Expressions</a>, Up: <a href="Data.html#Data" accesskey="u" rel="up">Data</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |