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<h3 class="section">17.27 Parameters for Precompiled Header Validity Checking</h3>
<p><a name="index-parameters_002c-precompiled-headers-4863"></a>
<div class="defun">
— Target Hook: void * <b>TARGET_GET_PCH_VALIDITY</b> (<var>size_t *sz</var>)<var><a name="index-TARGET_005fGET_005fPCH_005fVALIDITY-4864"></a></var><br>
<blockquote><p>This hook returns a pointer to the data needed by
<code>TARGET_PCH_VALID_P</code> and sets
‘<samp><span class="samp">*</span><var>sz</var></samp>’ to the size of the data in bytes.
</p></blockquote></div>
<div class="defun">
— Target Hook: const char * <b>TARGET_PCH_VALID_P</b> (<var>const void *data, size_t sz</var>)<var><a name="index-TARGET_005fPCH_005fVALID_005fP-4865"></a></var><br>
<blockquote><p>This hook checks whether the options used to create a PCH file are
compatible with the current settings. It returns <code>NULL</code>
if so and a suitable error message if not. Error messages will
be presented to the user and must be localized using ‘<samp><span class="samp">_(</span><var>msg</var><span class="samp">)</span></samp>’.
<p><var>data</var> is the data that was returned by <code>TARGET_GET_PCH_VALIDITY</code>
when the PCH file was created and <var>sz</var> is the size of that data in bytes.
It's safe to assume that the data was created by the same version of the
compiler, so no format checking is needed.
<p>The default definition of <code>default_pch_valid_p</code> should be
suitable for most targets.
</p></blockquote></div>
<div class="defun">
— Target Hook: const char * <b>TARGET_CHECK_PCH_TARGET_FLAGS</b> (<var>int pch_flags</var>)<var><a name="index-TARGET_005fCHECK_005fPCH_005fTARGET_005fFLAGS-4866"></a></var><br>
<blockquote><p>If this hook is nonnull, the default implementation of
<code>TARGET_PCH_VALID_P</code> will use it to check for compatible values
of <code>target_flags</code>. <var>pch_flags</var> specifies the value that
<code>target_flags</code> had when the PCH file was created. The return
value is the same as for <code>TARGET_PCH_VALID_P</code>.
</p></blockquote></div>
<div class="defun">
— Target Hook: void <b>TARGET_PREPARE_PCH_SAVE</b> (<var>void</var>)<var><a name="index-TARGET_005fPREPARE_005fPCH_005fSAVE-4867"></a></var><br>
<blockquote><p>Called before writing out a PCH file. If the target has some
garbage-collected data that needs to be in a particular state on PCH loads,
it can use this hook to enforce that state. Very few targets need
to do anything here.
</p></blockquote></div>
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