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95 lines
4.4 KiB
HTML
95 lines
4.4 KiB
HTML
4 years ago
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<html lang="en">
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<head>
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<title>Warnings and Errors - Using the GNU Compiler Collection (GCC)</title>
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<meta http-equiv="Content-Type" content="text/html">
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<meta name="description" content="Using the GNU Compiler Collection (GCC)">
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<meta name="generator" content="makeinfo 4.13">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="Trouble.html#Trouble" title="Trouble">
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<link rel="prev" href="Non_002dbugs.html#Non_002dbugs" title="Non-bugs">
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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<!--
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Copyright (C) 1988-2015 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being ``Funding Free Software'', the Front-Cover
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Texts being (a) (see below), and with the Back-Cover Texts being (b)
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(see below). A copy of the license is included in the section entitled
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``GNU Free Documentation License''.
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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software. Copies published by the Free Software Foundation raise
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funds for GNU development.-->
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<style type="text/css"><!--
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--></style>
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</head>
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<body>
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<div class="node">
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<a name="Warnings-and-Errors"></a>
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<p>
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Previous: <a rel="previous" accesskey="p" href="Non_002dbugs.html#Non_002dbugs">Non-bugs</a>,
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Up: <a rel="up" accesskey="u" href="Trouble.html#Trouble">Trouble</a>
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<hr>
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</div>
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<h3 class="section">12.9 Warning Messages and Error Messages</h3>
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<p><a name="index-error-messages-4295"></a><a name="index-warnings-vs-errors-4296"></a><a name="index-messages_002c-warning-and-error-4297"></a>The GNU compiler can produce two kinds of diagnostics: errors and
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warnings. Each kind has a different purpose:
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<ul>
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<li><dfn>Errors</dfn> report problems that make it impossible to compile your
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program. GCC reports errors with the source file name and line
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number where the problem is apparent.
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<li><dfn>Warnings</dfn> report other unusual conditions in your code that
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<em>may</em> indicate a problem, although compilation can (and does)
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proceed. Warning messages also report the source file name and line
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number, but include the text ‘<samp><span class="samp">warning:</span></samp>’ to distinguish them
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from error messages.
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</ul>
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<p>Warnings may indicate danger points where you should check to make sure
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that your program really does what you intend; or the use of obsolete
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features; or the use of nonstandard features of GNU C or C++. Many
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warnings are issued only if you ask for them, with one of the <samp><span class="option">-W</span></samp>
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options (for instance, <samp><span class="option">-Wall</span></samp> requests a variety of useful
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warnings).
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<p><a name="index-pedantic-4298"></a><a name="index-pedantic_002derrors-4299"></a>GCC always tries to compile your program if possible; it never
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gratuitously rejects a program whose meaning is clear merely because
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(for instance) it fails to conform to a standard. In some cases,
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however, the C and C++ standards specify that certain extensions are
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forbidden, and a diagnostic <em>must</em> be issued by a conforming
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compiler. The <samp><span class="option">-pedantic</span></samp> option tells GCC to issue warnings in
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such cases; <samp><span class="option">-pedantic-errors</span></samp> says to make them errors instead.
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This does not mean that <em>all</em> non-ISO constructs get warnings
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or errors.
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<p>See <a href="Warning-Options.html#Warning-Options">Options to Request or Suppress Warnings</a>, for
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more detail on these and related command-line options.
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<!-- Copyright (C) 1988-2015 Free Software Foundation, Inc. -->
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<!-- This is part of the GCC manual. -->
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<!-- For copying conditions, see the file gcc.texi. -->
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</body></html>
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