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| <div class="section" id="cmake-policy"> |
| <span id="command:cmake_policy"></span><h1>cmake_policy<a class="headerlink" href="#cmake-policy" title="Permalink to this headline">¶</a></h1> |
| <p>Manage CMake Policy settings. See the <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"><span class="pre">cmake-policies(7)</span></code></a> |
| manual for defined policies.</p> |
| <p>As CMake evolves it is sometimes necessary to change existing behavior |
| in order to fix bugs or improve implementations of existing features. |
| The CMake Policy mechanism is designed to help keep existing projects |
| building as new versions of CMake introduce changes in behavior. Each |
| new policy (behavioral change) is given an identifier of the form |
| <code class="docutils literal"><span class="pre">CMP<NNNN></span></code> where <code class="docutils literal"><span class="pre"><NNNN></span></code> is an integer index. Documentation |
| associated with each policy describes the <code class="docutils literal"><span class="pre">OLD</span></code> and <code class="docutils literal"><span class="pre">NEW</span></code> behavior |
| and the reason the policy was introduced. Projects may set each policy |
| to select the desired behavior. When CMake needs to know which behavior |
| to use it checks for a setting specified by the project. If no |
| setting is available the <code class="docutils literal"><span class="pre">OLD</span></code> behavior is assumed and a warning is |
| produced requesting that the policy be set.</p> |
| <div class="section" id="setting-policies-by-cmake-version"> |
| <h2>Setting Policies by CMake Version<a class="headerlink" href="#setting-policies-by-cmake-version" title="Permalink to this headline">¶</a></h2> |
| <p>The <code class="docutils literal"><span class="pre">cmake_policy</span></code> command is used to set policies to <code class="docutils literal"><span class="pre">OLD</span></code> or <code class="docutils literal"><span class="pre">NEW</span></code> |
| behavior. While setting policies individually is supported, we |
| encourage projects to set policies based on CMake versions:</p> |
| <div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">cmake_policy</span><span class="p">(</span><span class="n">VERSION</span> <span class="n">major</span><span class="o">.</span><span class="n">minor</span><span class="p">[</span><span class="o">.</span><span class="n">patch</span><span class="p">[</span><span class="o">.</span><span class="n">tweak</span><span class="p">]])</span> |
| </pre></div> |
| </div> |
| <p>Specify that the current CMake code is written for the given |
| version of CMake. All policies introduced in the specified version or |
| earlier will be set to use <code class="docutils literal"><span class="pre">NEW</span></code> behavior. All policies introduced |
| after the specified version will be unset (unless the |
| <span class="target" id="index-0-variable:CMAKE_POLICY_DEFAULT_CMP<NNNN>"></span><a class="reference internal" href="../variable/CMAKE_POLICY_DEFAULT_CMPNNNN.html#variable:CMAKE_POLICY_DEFAULT_CMP<NNNN>" title="CMAKE_POLICY_DEFAULT_CMP<NNNN>"><code class="xref cmake cmake-variable docutils literal"><span class="pre">CMAKE_POLICY_DEFAULT_CMP<NNNN></span></code></a> variable sets a default). |
| This effectively requests behavior preferred as of a given CMake |
| version and tells newer CMake versions to warn about their new policies. |
| The policy version specified must be at least 2.4 or the command will |
| report an error.</p> |
| <p>Note that the <span class="target" id="index-0-command:cmake_minimum_required"></span><a class="reference internal" href="cmake_minimum_required.html#command:cmake_minimum_required" title="cmake_minimum_required"><code class="xref cmake cmake-command docutils literal"><span class="pre">cmake_minimum_required(VERSION)</span></code></a> |
| command implicitly calls <code class="docutils literal"><span class="pre">cmake_policy(VERSION)</span></code> too.</p> |
| </div> |
| <div class="section" id="setting-policies-explicitly"> |
| <h2>Setting Policies Explicitly<a class="headerlink" href="#setting-policies-explicitly" title="Permalink to this headline">¶</a></h2> |
| <div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">cmake_policy</span><span class="p">(</span><span class="n">SET</span> <span class="n">CMP</span><span class="o"><</span><span class="n">NNNN</span><span class="o">></span> <span class="n">NEW</span><span class="p">)</span> |
| <span class="n">cmake_policy</span><span class="p">(</span><span class="n">SET</span> <span class="n">CMP</span><span class="o"><</span><span class="n">NNNN</span><span class="o">></span> <span class="n">OLD</span><span class="p">)</span> |
| </pre></div> |
| </div> |
| <p>Tell CMake to use the <code class="docutils literal"><span class="pre">OLD</span></code> or <code class="docutils literal"><span class="pre">NEW</span></code> behavior for a given policy. |
| Projects depending on the old behavior of a given policy may silence a |
| policy warning by setting the policy state to <code class="docutils literal"><span class="pre">OLD</span></code>. Alternatively |
| one may fix the project to work with the new behavior and set the |
| policy state to <code class="docutils literal"><span class="pre">NEW</span></code>.</p> |
| <div class="admonition note"> |
| <p class="first admonition-title">Note</p> |
| <p class="last">The <code class="docutils literal"><span class="pre">OLD</span></code> behavior of a policy is |
| <span class="target" id="index-1-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"><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> |
| </div> |
| </div> |
| <div class="section" id="checking-policy-settings"> |
| <h2>Checking Policy Settings<a class="headerlink" href="#checking-policy-settings" title="Permalink to this headline">¶</a></h2> |
| <div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">cmake_policy</span><span class="p">(</span><span class="n">GET</span> <span class="n">CMP</span><span class="o"><</span><span class="n">NNNN</span><span class="o">></span> <span class="o"><</span><span class="n">variable</span><span class="o">></span><span class="p">)</span> |
| </pre></div> |
| </div> |
| <p>Check whether a given policy is set to <code class="docutils literal"><span class="pre">OLD</span></code> or <code class="docutils literal"><span class="pre">NEW</span></code> behavior. |
| The output <code class="docutils literal"><span class="pre"><variable></span></code> value will be <code class="docutils literal"><span class="pre">OLD</span></code> or <code class="docutils literal"><span class="pre">NEW</span></code> if the |
| policy is set, and empty otherwise.</p> |
| </div> |
| <div class="section" id="cmake-policy-stack"> |
| <h2>CMake Policy Stack<a class="headerlink" href="#cmake-policy-stack" title="Permalink to this headline">¶</a></h2> |
| <p>CMake keeps policy settings on a stack, so changes made by the |
| cmake_policy command affect only the top of the stack. A new entry on |
| the policy stack is managed automatically for each subdirectory to |
| protect its parents and siblings. CMake also manages a new entry for |
| scripts loaded by <span class="target" id="index-0-command:include"></span><a class="reference internal" href="include.html#command:include" title="include"><code class="xref cmake cmake-command docutils literal"><span class="pre">include()</span></code></a> and <span class="target" id="index-0-command:find_package"></span><a class="reference internal" href="find_package.html#command:find_package" title="find_package"><code class="xref cmake cmake-command docutils literal"><span class="pre">find_package()</span></code></a> commands |
| except when invoked with the <code class="docutils literal"><span class="pre">NO_POLICY_SCOPE</span></code> option |
| (see also policy <span class="target" id="index-0-policy:CMP0011"></span><a class="reference internal" href="../policy/CMP0011.html#policy:CMP0011" title="CMP0011"><code class="xref cmake cmake-policy docutils literal"><span class="pre">CMP0011</span></code></a>). |
| The <code class="docutils literal"><span class="pre">cmake_policy</span></code> command provides an interface to manage custom |
| entries on the policy stack:</p> |
| <div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">cmake_policy</span><span class="p">(</span><span class="n">PUSH</span><span class="p">)</span> |
| <span class="n">cmake_policy</span><span class="p">(</span><span class="n">POP</span><span class="p">)</span> |
| </pre></div> |
| </div> |
| <p>Each <code class="docutils literal"><span class="pre">PUSH</span></code> must have a matching <code class="docutils literal"><span class="pre">POP</span></code> to erase any changes. |
| This is useful to make temporary changes to policy settings. |
| Calls to the <span class="target" id="index-1-command:cmake_minimum_required"></span><a class="reference internal" href="cmake_minimum_required.html#command:cmake_minimum_required" title="cmake_minimum_required"><code class="xref cmake cmake-command docutils literal"><span class="pre">cmake_minimum_required(VERSION)</span></code></a>, |
| <code class="docutils literal"><span class="pre">cmake_policy(VERSION)</span></code>, or <code class="docutils literal"><span class="pre">cmake_policy(SET)</span></code> commands |
| influence only the current top of the policy stack.</p> |
| <p>Commands created by the <span class="target" id="index-0-command:function"></span><a class="reference internal" href="function.html#command:function" title="function"><code class="xref cmake cmake-command docutils literal"><span class="pre">function()</span></code></a> and <span class="target" id="index-0-command:macro"></span><a class="reference internal" href="macro.html#command:macro" title="macro"><code class="xref cmake cmake-command docutils literal"><span class="pre">macro()</span></code></a> |
| commands record policy settings when they are created and |
| use the pre-record policies when they are invoked. If the function or |
| macro implementation sets policies, the changes automatically |
| propagate up through callers until they reach the closest nested |
| policy stack entry.</p> |
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| <li><a class="reference internal" href="#">cmake_policy</a><ul> |
| <li><a class="reference internal" href="#setting-policies-by-cmake-version">Setting Policies by CMake Version</a></li> |
| <li><a class="reference internal" href="#setting-policies-explicitly">Setting Policies Explicitly</a></li> |
| <li><a class="reference internal" href="#checking-policy-settings">Checking Policy Settings</a></li> |
| <li><a class="reference internal" href="#cmake-policy-stack">CMake Policy Stack</a></li> |
| </ul> |
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