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| <div class="section" id="checktypesize"> | |
| <span id="module:CheckTypeSize"></span><h1>CheckTypeSize<a class="headerlink" href="#checktypesize" title="Permalink to this headline">¶</a></h1> | |
| <p>Check sizeof a type</p> | |
| <dl class="command"> | |
| <dt id="command:check_type_size"> | |
| <code class="sig-name descname">check_type_size</code><a class="headerlink" href="#command:check_type_size" title="Permalink to this definition">¶</a></dt> | |
| <dd><div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">check_type_size(</span><span class="nv"><type></span><span class="w"> </span><span class="nv"><variable></span><span class="w"> </span><span class="p">[</span><span class="no">BUILTIN_TYPES_ONLY</span><span class="p">]</span><span class="w"></span> | |
| <span class="w"> </span><span class="p">[</span><span class="no">LANGUAGE</span><span class="w"> </span><span class="nv"><language></span><span class="p">]</span><span class="nf">)</span><span class="w"></span> | |
| </pre></div> | |
| </div> | |
| <p>Check if the type exists and determine its size. Results are reported | |
| in the following variables:</p> | |
| <dl> | |
| <dt><code class="docutils literal notranslate"><span class="pre">HAVE_<variable></span></code></dt><dd><p>Holds a true or false value indicating whether the type exists.</p> | |
| </dd> | |
| <dt><code class="docutils literal notranslate"><span class="pre"><variable></span></code></dt><dd><p>Holds one of the following values:</p> | |
| <dl class="simple"> | |
| <dt><code class="docutils literal notranslate"><span class="pre"><size></span></code></dt><dd><p>Type has non-zero size <code class="docutils literal notranslate"><span class="pre"><size></span></code>.</p> | |
| </dd> | |
| <dt><code class="docutils literal notranslate"><span class="pre">0</span></code></dt><dd><p>Type has architecture-dependent size. This may occur when | |
| <span class="target" id="index-0-variable:CMAKE_OSX_ARCHITECTURES"></span><a class="reference internal" href="../variable/CMAKE_OSX_ARCHITECTURES.html#variable:CMAKE_OSX_ARCHITECTURES" title="CMAKE_OSX_ARCHITECTURES"><code class="xref cmake cmake-variable docutils literal notranslate"><span class="pre">CMAKE_OSX_ARCHITECTURES</span></code></a> has multiple architectures. | |
| In this case <code class="docutils literal notranslate"><span class="pre"><variable>_CODE</span></code> contains C preprocessor tests | |
| mapping from each architecture macro to the corresponding type size. | |
| The list of architecture macros is stored in <code class="docutils literal notranslate"><span class="pre"><variable>_KEYS</span></code>, | |
| and the value for each key is stored in <code class="docutils literal notranslate"><span class="pre"><variable>-<key></span></code>.</p> | |
| </dd> | |
| <dt>"" (empty string)</dt><dd><p>Type does not exist.</p> | |
| </dd> | |
| </dl> | |
| </dd> | |
| <dt><code class="docutils literal notranslate"><span class="pre"><variable>_CODE</span></code></dt><dd><p>Holds C preprocessor code to define the macro <code class="docutils literal notranslate"><span class="pre"><variable></span></code> to the size | |
| of the type, or to leave the macro undefined if the type does not exist.</p> | |
| </dd> | |
| </dl> | |
| <p>The options are:</p> | |
| <p><code class="docutils literal notranslate"><span class="pre">BUILTIN_TYPES_ONLY</span></code></p> | |
| <blockquote> | |
| <div><p>Support only compiler-builtin types. If <em>not</em> given, the macro checks | |
| for headers <code class="docutils literal notranslate"><span class="pre"><sys/types.h></span></code>, <code class="docutils literal notranslate"><span class="pre"><stdint.h></span></code>, and <code class="docutils literal notranslate"><span class="pre"><stddef.h></span></code>, and | |
| saves results in <code class="docutils literal notranslate"><span class="pre">HAVE_SYS_TYPES_H</span></code>, <code class="docutils literal notranslate"><span class="pre">HAVE_STDINT_H</span></code>, and | |
| <code class="docutils literal notranslate"><span class="pre">HAVE_STDDEF_H</span></code>. The type size check automatically includes the | |
| available headers, thus supporting checks of types defined in the headers.</p> | |
| </div></blockquote> | |
| <dl class="simple"> | |
| <dt><code class="docutils literal notranslate"><span class="pre">LANGUAGE</span> <span class="pre"><language></span></code></dt><dd><p>Use the <code class="docutils literal notranslate"><span class="pre"><language></span></code> compiler to perform the check. | |
| Acceptable values are <code class="docutils literal notranslate"><span class="pre">C</span></code> and <code class="docutils literal notranslate"><span class="pre">CXX</span></code>.</p> | |
| </dd> | |
| </dl> | |
| </dd></dl> | |
| <p>Despite the name of the macro you may use it to check the size of more | |
| complex expressions, too. To check e.g. for the size of a struct | |
| member you can do something like this:</p> | |
| <div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">check_type_size(</span><span class="s">"((struct something*)0)->member"</span><span class="w"> </span><span class="no">SIZEOF_MEMBER</span><span class="nf">)</span><span class="w"></span> | |
| </pre></div> | |
| </div> | |
| <p>The following variables may be set before calling this macro to modify | |
| the way the check is run:</p> | |
| <dl> | |
| <dt><code class="docutils literal notranslate"><span class="pre">CMAKE_REQUIRED_FLAGS</span></code></dt><dd><p>string of compile command line flags.</p> | |
| </dd> | |
| <dt><code class="docutils literal notranslate"><span class="pre">CMAKE_REQUIRED_DEFINITIONS</span></code></dt><dd><p>list of macros to define (-DFOO=bar).</p> | |
| </dd> | |
| <dt><code class="docutils literal notranslate"><span class="pre">CMAKE_REQUIRED_INCLUDES</span></code></dt><dd><p>list of include directories.</p> | |
| </dd> | |
| <dt><code class="docutils literal notranslate"><span class="pre">CMAKE_REQUIRED_LINK_OPTIONS</span></code></dt><dd><div class="versionadded"> | |
| <p><span class="versionmodified added">New in version 3.14: </span>list of options to pass to link command.</p> | |
| </div> | |
| </dd> | |
| <dt><code class="docutils literal notranslate"><span class="pre">CMAKE_REQUIRED_LIBRARIES</span></code></dt><dd><p>list of libraries to link.</p> | |
| </dd> | |
| <dt><code class="docutils literal notranslate"><span class="pre">CMAKE_REQUIRED_QUIET</span></code></dt><dd><div class="versionadded"> | |
| <p><span class="versionmodified added">New in version 3.1: </span>execute quietly without messages.</p> | |
| </div> | |
| </dd> | |
| <dt><code class="docutils literal notranslate"><span class="pre">CMAKE_EXTRA_INCLUDE_FILES</span></code></dt><dd><p>list of extra headers to include.</p> | |
| </dd> | |
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