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| <div class="section" id="cmp0126"> |
| <span id="policy:CMP0126"></span><h1>CMP0126<a class="headerlink" href="#cmp0126" title="Permalink to this headline">ΒΆ</a></h1> |
| <div class="versionadded"> |
| <p><span class="versionmodified added">New in version 3.21.</span></p> |
| </div> |
| <p>When this policy is set to <code class="docutils literal notranslate"><span class="pre">NEW</span></code>, the <span class="target" id="index-0-command:set"></span><a class="reference internal" href="../command/set.html#command:set" title="set"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">set(CACHE)</span></code></a> command does not |
| remove any normal variable of the same name from the current scope. |
| The <code class="docutils literal notranslate"><span class="pre">OLD</span></code> behavior removes any normal variable of the same name from the |
| current scope in the following situations:</p> |
| <ul class="simple"> |
| <li><p>No cache variable of that name existed previously.</p></li> |
| <li><p>A cache variable of that name existed previously, but it had no type. |
| This can occur when the variable was set on the command line using a form |
| like <code class="docutils literal notranslate"><span class="pre">cmake</span> <span class="pre">-DMYVAR=blah</span></code> instead of <code class="docutils literal notranslate"><span class="pre">cmake</span> <span class="pre">-DMYVAR:STRING=blah</span></code>.</p></li> |
| <li><p>The <code class="docutils literal notranslate"><span class="pre">FORCE</span></code> or <code class="docutils literal notranslate"><span class="pre">INTERNAL</span></code> keywords were used when setting the cache |
| variable.</p></li> |
| </ul> |
| <p>Note that the <code class="docutils literal notranslate"><span class="pre">NEW</span></code> behavior has an important difference to the similar |
| <code class="docutils literal notranslate"><span class="pre">NEW</span></code> behavior of policy <span class="target" id="index-0-policy:CMP0077"></span><a class="reference internal" href="CMP0077.html#policy:CMP0077" title="CMP0077"><code class="xref cmake cmake-policy docutils literal notranslate"><span class="pre">CMP0077</span></code></a>. The <span class="target" id="index-1-command:set"></span><a class="reference internal" href="../command/set.html#command:set" title="set"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">set(CACHE)</span></code></a> |
| command always sets the cache variable if it did not exist previously, |
| regardless of the <code class="docutils literal notranslate"><span class="pre">CMP0126</span></code> policy setting. The <span class="target" id="index-0-command:option"></span><a class="reference internal" href="../command/option.html#command:option" title="option"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">option()</span></code></a> command |
| will <em>not</em> set the cache variable if a non-cache variable of the same name |
| already exists and <span class="target" id="index-1-policy:CMP0077"></span><a class="reference internal" href="CMP0077.html#policy:CMP0077" title="CMP0077"><code class="xref cmake cmake-policy docutils literal notranslate"><span class="pre">CMP0077</span></code></a> is set to <code class="docutils literal notranslate"><span class="pre">NEW</span></code>.</p> |
| <p>Policy <code class="docutils literal notranslate"><span class="pre">CMP0126</span></code> was introduced in CMake version 3.21. 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 |
| within a project. Use 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 notranslate"><span class="pre">CMAKE_POLICY_DEFAULT_CMP0126</span></code></a> variable to set the policy for |
| a third-party project in a subdirectory without modifying it. |
| Unlike many policies, CMake version 3.23.1 does <em>not</em> warn when the policy |
| is not set and simply uses <code class="docutils literal notranslate"><span class="pre">OLD</span></code> behavior. See documentation of the |
| <span class="target" id="index-0-variable:CMAKE_POLICY_WARNING_CMP<NNNN>"></span><a class="reference internal" href="../variable/CMAKE_POLICY_WARNING_CMPNNNN.html#variable:CMAKE_POLICY_WARNING_CMP<NNNN>" title="CMAKE_POLICY_WARNING_CMP<NNNN>"><code class="xref cmake cmake-variable docutils literal notranslate"><span class="pre">CMAKE_POLICY_WARNING_CMP0126</span></code></a> |
| variable to control the warning.</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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