130 lines
5.7 KiB
HTML
130 lines
5.7 KiB
HTML
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Permission is granted to copy, distribute and/or modify this document
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any later version published by the Free Software Foundation; with the
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Using the GNU Compiler Collection (GCC): Warnings and Errors</title>
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<meta name="description" content="Using the GNU Compiler Collection (GCC): Warnings and Errors">
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<meta name="keywords" content="Using the GNU Compiler Collection (GCC): Warnings and Errors">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Trouble.html#Trouble" rel="up" title="Trouble">
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<link href="Bugs.html#Bugs" rel="next" title="Bugs">
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<link href="Non_002dbugs.html#Non_002dbugs" rel="prev" title="Non-bugs">
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</head>
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="Warnings-and-Errors"></a>
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<div class="header">
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<p>
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Previous: <a href="Non_002dbugs.html#Non_002dbugs" accesskey="p" rel="prev">Non-bugs</a>, Up: <a href="Trouble.html#Trouble" accesskey="u" rel="up">Trouble</a> [<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>
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</div>
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<hr>
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<a name="Warning-Messages-and-Error-Messages"></a>
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<h3 class="section">12.9 Warning Messages and Error Messages</h3>
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<a name="index-error-messages"></a>
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<a name="index-warnings-vs-errors"></a>
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<a name="index-messages_002c-warning-and-error"></a>
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<p>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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</p>
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<ul class="no-bullet">
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<li><!-- /@w --> <em>Errors</em> 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><li><!-- /@w --> <em>Warnings</em> 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>warning:</samp>’ to distinguish them
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from error messages.
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</li></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>-W</samp>
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options (for instance, <samp>-Wall</samp> requests a variety of useful
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warnings).
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</p>
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<a name="index-pedantic-5"></a>
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<a name="index-pedantic_002derrors-4"></a>
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<p>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>-pedantic</samp> option tells GCC to issue warnings in
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such cases; <samp>-pedantic-errors</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>
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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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</p>
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<hr>
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<div class="header">
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<p>
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Previous: <a href="Non_002dbugs.html#Non_002dbugs" accesskey="p" rel="prev">Non-bugs</a>, Up: <a href="Trouble.html#Trouble" accesskey="u" rel="up">Trouble</a> [<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>
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</div>
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</body>
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</html>
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