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| <title>Using the GNU Compiler Collection (GCC): Warnings and Errors</title> |
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| <a name="Warnings-and-Errors"></a> |
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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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| <a name="Warning-Messages-and-Error-Messages"></a> |
| <h3 class="section">11.9 Warning Messages and Error Messages</h3> |
| |
| <a name="index-error-messages"></a> |
| <a name="index-warnings-vs-errors"></a> |
| <a name="index-messages_002c-warning-and-error"></a> |
| <p>The GNU compiler can produce two kinds of diagnostics: errors and |
| warnings. Each kind has a different purpose: |
| </p> |
| <ul class="no-bullet"> |
| <li><!-- /@w --> <em>Errors</em> report problems that make it impossible to compile your |
| program. GCC reports errors with the source file name and line |
| number where the problem is apparent. |
| |
| </li><li><!-- /@w --> <em>Warnings</em> report other unusual conditions in your code that |
| <em>may</em> indicate a problem, although compilation can (and does) |
| proceed. Warning messages also report the source file name and line |
| number, but include the text ‘<samp>warning:</samp>’ to distinguish them |
| from error messages. |
| </li></ul> |
| |
| <p>Warnings may indicate danger points where you should check to make sure |
| that your program really does what you intend; or the use of obsolete |
| features; or the use of nonstandard features of GNU C or C++. Many |
| warnings are issued only if you ask for them, with one of the <samp>-W</samp> |
| options (for instance, <samp>-Wall</samp> requests a variety of useful |
| warnings). |
| </p> |
| <a name="index-pedantic-5"></a> |
| <a name="index-pedantic_002derrors-4"></a> |
| <p>GCC always tries to compile your program if possible; it never |
| gratuitously rejects a program whose meaning is clear merely because |
| (for instance) it fails to conform to a standard. In some cases, |
| however, the C and C++ standards specify that certain extensions are |
| forbidden, and a diagnostic <em>must</em> be issued by a conforming |
| compiler. The <samp>-pedantic</samp> option tells GCC to issue warnings in |
| such cases; <samp>-pedantic-errors</samp> says to make them errors instead. |
| This does not mean that <em>all</em> non-ISO constructs get warnings |
| or errors. |
| </p> |
| <p>See <a href="Warning-Options.html#Warning-Options">Options to Request or Suppress Warnings</a>, for |
| more detail on these and related command-line options. |
| </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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