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<div class="section" id="cmp0092">
<span id="policy:CMP0092"></span><h1>CMP0092<a class="headerlink" href="#cmp0092" title="Permalink to this headline">ΒΆ</a></h1>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.15.</span></p>
</div>
<p>MSVC warning flags are not in <span class="target" id="index-0-variable:CMAKE_&lt;LANG&gt;_FLAGS"></span><a class="reference internal" href="../variable/CMAKE_LANG_FLAGS.html#variable:CMAKE_&lt;LANG&gt;_FLAGS" title="CMAKE_&lt;LANG&gt;_FLAGS"><code class="xref cmake cmake-variable docutils literal notranslate"><span class="pre">CMAKE_&lt;LANG&gt;_FLAGS</span></code></a> by default.</p>
<p>When using MSVC-like compilers in CMake 3.14 and below, warning flags
like <code class="docutils literal notranslate"><span class="pre">/W3</span></code> are added to <span class="target" id="index-1-variable:CMAKE_&lt;LANG&gt;_FLAGS"></span><a class="reference internal" href="../variable/CMAKE_LANG_FLAGS.html#variable:CMAKE_&lt;LANG&gt;_FLAGS" title="CMAKE_&lt;LANG&gt;_FLAGS"><code class="xref cmake cmake-variable docutils literal notranslate"><span class="pre">CMAKE_&lt;LANG&gt;_FLAGS</span></code></a> by default.
This is problematic for projects that want to choose a different warning
level programmatically. In particular, it requires string editing of the
<span class="target" id="index-2-variable:CMAKE_&lt;LANG&gt;_FLAGS"></span><a class="reference internal" href="../variable/CMAKE_LANG_FLAGS.html#variable:CMAKE_&lt;LANG&gt;_FLAGS" title="CMAKE_&lt;LANG&gt;_FLAGS"><code class="xref cmake cmake-variable docutils literal notranslate"><span class="pre">CMAKE_&lt;LANG&gt;_FLAGS</span></code></a> variables with knowledge of the
CMake builtin defaults so they can be replaced.</p>
<p>CMake 3.15 and above prefer to leave out warning flags from the value of
<span class="target" id="index-3-variable:CMAKE_&lt;LANG&gt;_FLAGS"></span><a class="reference internal" href="../variable/CMAKE_LANG_FLAGS.html#variable:CMAKE_&lt;LANG&gt;_FLAGS" title="CMAKE_&lt;LANG&gt;_FLAGS"><code class="xref cmake cmake-variable docutils literal notranslate"><span class="pre">CMAKE_&lt;LANG&gt;_FLAGS</span></code></a> by default.</p>
<p>This policy provides compatibility with projects that have not been updated
to expect the lack of warning flags. The policy setting takes effect as of
the first <span class="target" id="index-0-command:project"></span><a class="reference internal" href="../command/project.html#command:project" title="project"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">project()</span></code></a> or <span class="target" id="index-0-command:enable_language"></span><a class="reference internal" href="../command/enable_language.html#command:enable_language" title="enable_language"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">enable_language()</span></code></a> command that
initializes <span class="target" id="index-4-variable:CMAKE_&lt;LANG&gt;_FLAGS"></span><a class="reference internal" href="../variable/CMAKE_LANG_FLAGS.html#variable:CMAKE_&lt;LANG&gt;_FLAGS" title="CMAKE_&lt;LANG&gt;_FLAGS"><code class="xref cmake cmake-variable docutils literal notranslate"><span class="pre">CMAKE_&lt;LANG&gt;_FLAGS</span></code></a> for a given language <code class="docutils literal notranslate"><span class="pre">&lt;LANG&gt;</span></code>.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Once the policy has taken effect at the top of a project for a given
language, that choice must be used throughout the tree for that language.
In projects that have nested projects in subdirectories, be sure to
convert everything together.</p>
</div>
<p>The <code class="docutils literal notranslate"><span class="pre">OLD</span></code> behavior for this policy is to place MSVC warning flags in the
default <span class="target" id="index-5-variable:CMAKE_&lt;LANG&gt;_FLAGS"></span><a class="reference internal" href="../variable/CMAKE_LANG_FLAGS.html#variable:CMAKE_&lt;LANG&gt;_FLAGS" title="CMAKE_&lt;LANG&gt;_FLAGS"><code class="xref cmake cmake-variable docutils literal notranslate"><span class="pre">CMAKE_&lt;LANG&gt;_FLAGS</span></code></a> cache entries. The <code class="docutils literal notranslate"><span class="pre">NEW</span></code> behavior
for this policy is to <em>not</em> place MSVC warning flags in the default cache
entries.</p>
<p>This policy was introduced in CMake version 3.15. Use the
<span class="target" id="index-0-command:cmake_policy"></span><a class="reference internal" href="../command/cmake_policy.html#command:cmake_policy" title="cmake_policy"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">cmake_policy()</span></code></a> command to set it to <code class="docutils literal notranslate"><span class="pre">OLD</span></code> or <code class="docutils literal notranslate"><span class="pre">NEW</span></code> explicitly.
Unlike many policies, CMake version 3.23.1 does <em>not</em> warn
when this policy is not set and simply uses <code class="docutils literal notranslate"><span class="pre">OLD</span></code> behavior.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>The <code class="docutils literal notranslate"><span class="pre">OLD</span></code> behavior of a policy is
<span class="target" id="index-0-manual:cmake-policies(7)"></span><a class="reference internal" href="../manual/cmake-policies.7.html#manual:cmake-policies(7)" title="cmake-policies(7)"><code class="xref cmake cmake-manual docutils literal notranslate"><span class="pre">deprecated</span> <span class="pre">by</span> <span class="pre">definition</span></code></a>
and may be removed in a future version of CMake.</p>
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