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| <h3 class="section">11.10 Warning Messages and Error Messages</h3> |
| |
| <p><a name="index-error-messages-3250"></a><a name="index-warnings-vs-errors-3251"></a><a name="index-messages_002c-warning-and-error-3252"></a>The GNU compiler can produce two kinds of diagnostics: errors and |
| warnings. Each kind has a different purpose: |
| |
| <ul> |
| <li><dfn>Errors</dfn> 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><dfn>Warnings</dfn> 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><span class="samp">warning:</span></samp>’ to distinguish them |
| from error messages. |
| </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><span class="option">-W</span></samp> |
| options (for instance, <samp><span class="option">-Wall</span></samp> requests a variety of useful |
| warnings). |
| |
| <p><a name="index-pedantic-3253"></a><a name="index-pedantic_002derrors-3254"></a>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><span class="option">-pedantic</span></samp> option tells GCC to issue warnings in |
| such cases; <samp><span class="option">-pedantic-errors</span></samp> says to make them errors instead. |
| This does not mean that <em>all</em> non-ISO constructs get warnings |
| or errors. |
| |
| <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. |
| |
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