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| <a name="Diagnostic-Pragmas"></a> |
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| Next: <a href="Visibility-Pragmas.html#Visibility-Pragmas" accesskey="n" rel="next">Visibility Pragmas</a>, Previous: <a href="Weak-Pragmas.html#Weak-Pragmas" accesskey="p" rel="prev">Weak Pragmas</a>, Up: <a href="Pragmas.html#Pragmas" accesskey="u" rel="up">Pragmas</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="Diagnostic-Pragmas-1"></a> |
| <h4 class="subsection">6.59.10 Diagnostic Pragmas</h4> |
| |
| <p>GCC allows the user to selectively enable or disable certain types of |
| diagnostics, and change the kind of the diagnostic. For example, a |
| project’s policy might require that all sources compile with |
| <samp>-Werror</samp> but certain files might have exceptions allowing |
| specific types of warnings. Or, a project might selectively enable |
| diagnostics and treat them as errors depending on which preprocessor |
| macros are defined. |
| </p> |
| <dl compact="compact"> |
| <dt><code>#pragma GCC diagnostic <var>kind</var> <var>option</var></code></dt> |
| <dd><a name="index-pragma_002c-diagnostic"></a> |
| |
| <p>Modifies the disposition of a diagnostic. Note that not all |
| diagnostics are modifiable; at the moment only warnings (normally |
| controlled by ‘<samp>-W…</samp>’) can be controlled, and not all of them. |
| Use <samp>-fdiagnostics-show-option</samp> to determine which diagnostics |
| are controllable and which option controls them. |
| </p> |
| <p><var>kind</var> is ‘<samp>error</samp>’ to treat this diagnostic as an error, |
| ‘<samp>warning</samp>’ to treat it like a warning (even if <samp>-Werror</samp> is |
| in effect), or ‘<samp>ignored</samp>’ if the diagnostic is to be ignored. |
| <var>option</var> is a double quoted string that matches the command-line |
| option. |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">#pragma GCC diagnostic warning "-Wformat" |
| #pragma GCC diagnostic error "-Wformat" |
| #pragma GCC diagnostic ignored "-Wformat" |
| </pre></div> |
| |
| <p>Note that these pragmas override any command-line options. GCC keeps |
| track of the location of each pragma, and issues diagnostics according |
| to the state as of that point in the source file. Thus, pragmas occurring |
| after a line do not affect diagnostics caused by that line. |
| </p> |
| </dd> |
| <dt><code>#pragma GCC diagnostic push</code></dt> |
| <dt><code>#pragma GCC diagnostic pop</code></dt> |
| <dd> |
| <p>Causes GCC to remember the state of the diagnostics as of each |
| <code>push</code>, and restore to that point at each <code>pop</code>. If a |
| <code>pop</code> has no matching <code>push</code>, the command-line options are |
| restored. |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">#pragma GCC diagnostic error "-Wuninitialized" |
| foo(a); /* error is given for this one */ |
| #pragma GCC diagnostic push |
| #pragma GCC diagnostic ignored "-Wuninitialized" |
| foo(b); /* no diagnostic for this one */ |
| #pragma GCC diagnostic pop |
| foo(c); /* error is given for this one */ |
| #pragma GCC diagnostic pop |
| foo(d); /* depends on command-line options */ |
| </pre></div> |
| |
| </dd> |
| </dl> |
| |
| <p>GCC also offers a simple mechanism for printing messages during |
| compilation. |
| </p> |
| <dl compact="compact"> |
| <dt><code>#pragma message <var>string</var></code></dt> |
| <dd><a name="index-pragma_002c-diagnostic-1"></a> |
| |
| <p>Prints <var>string</var> as a compiler message on compilation. The message |
| is informational only, and is neither a compilation warning nor an error. |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">#pragma message "Compiling " __FILE__ "..." |
| </pre></div> |
| |
| <p><var>string</var> may be parenthesized, and is printed with location |
| information. For example, |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">#define DO_PRAGMA(x) _Pragma (#x) |
| #define TODO(x) DO_PRAGMA(message ("TODO - " #x)) |
| |
| TODO(Remember to fix this) |
| </pre></div> |
| |
| <p>prints ‘<samp>/tmp/file.c:4: note: #pragma message: |
| TODO - Remember to fix this</samp>’. |
| </p> |
| </dd> |
| </dl> |
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| Next: <a href="Visibility-Pragmas.html#Visibility-Pragmas" accesskey="n" rel="next">Visibility Pragmas</a>, Previous: <a href="Weak-Pragmas.html#Weak-Pragmas" accesskey="p" rel="prev">Weak Pragmas</a>, Up: <a href="Pragmas.html#Pragmas" accesskey="u" rel="up">Pragmas</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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