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| <div class="section" id="cmp0114"> |
| <span id="policy:CMP0114"></span><h1>CMP0114<a class="headerlink" href="#cmp0114" title="Permalink to this headline">ΒΆ</a></h1> |
| <div class="versionadded"> |
| <p><span class="versionmodified added">New in version 3.19.</span></p> |
| </div> |
| <p><span class="target" id="index-0-module:ExternalProject"></span><a class="reference internal" href="../module/ExternalProject.html#module:ExternalProject" title="ExternalProject"><code class="xref cmake cmake-module docutils literal notranslate"><span class="pre">ExternalProject</span></code></a> step targets fully adopt their steps.</p> |
| <p>The <span class="target" id="index-0-command:externalproject_add"></span><a class="reference internal" href="../module/ExternalProject.html#command:externalproject_add" title="externalproject_add"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">ExternalProject_Add()</span></code></a> <code class="docutils literal notranslate"><span class="pre">STEP_TARGETS</span></code> option, and the |
| <span class="target" id="index-0-command:externalproject_add_steptargets"></span><a class="reference internal" href="../module/ExternalProject.html#command:externalproject_add_steptargets" title="externalproject_add_steptargets"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">ExternalProject_Add_StepTargets()</span></code></a> function, can be used to |
| create build targets for individual steps of an external project.</p> |
| <p>In CMake 3.18 and below, step targets have some limitations:</p> |
| <ul> |
| <li><p>Step targets always depend on targets named by the |
| <span class="target" id="index-1-command:externalproject_add"></span><a class="reference internal" href="../module/ExternalProject.html#command:externalproject_add" title="externalproject_add"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">ExternalProject_Add()</span></code></a> <code class="docutils literal notranslate"><span class="pre">DEPENDS</span></code> option even though |
| not all steps need them. In order to allow step targets to be created |
| without those dependencies, the <span class="target" id="index-2-command:externalproject_add"></span><a class="reference internal" href="../module/ExternalProject.html#command:externalproject_add" title="externalproject_add"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">ExternalProject_Add()</span></code></a> |
| <code class="docutils literal notranslate"><span class="pre">INDEPENDENT_STEP_TARGETS</span></code> option or the |
| <span class="target" id="index-1-command:externalproject_add_steptargets"></span><a class="reference internal" href="../module/ExternalProject.html#command:externalproject_add_steptargets" title="externalproject_add_steptargets"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">ExternalProject_Add_StepTargets()</span></code></a> <code class="docutils literal notranslate"><span class="pre">NO_DEPENDS</span></code> option may |
| be used. However, adding such "independent" step targets makes sense |
| only for specific steps such as <code class="docutils literal notranslate"><span class="pre">download</span></code>, <code class="docutils literal notranslate"><span class="pre">update</span></code>, and <code class="docutils literal notranslate"><span class="pre">patch</span></code> |
| because they do not need any of the external project's build dependencies. |
| Furthermore, it does not make sense to create independent step targets |
| for steps that depend on non-independent steps. Such rules are not |
| enforced, and projects that do not follow them can generate build systems |
| with confusing and generator-specific behavior.</p></li> |
| <li><p>Step targets hold copies of the custom commands implementing their |
| steps that are separate from the copies in the primary target created |
| by <span class="target" id="index-3-command:externalproject_add"></span><a class="reference internal" href="../module/ExternalProject.html#command:externalproject_add" title="externalproject_add"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">ExternalProject_Add()</span></code></a>, and the primary target does not |
| depend on the step targets. In parallel builds that drive the primary |
| target and step targets concurrently, multiple copies of the steps' |
| commands may run concurrently and race each other.</p> |
| <p>Also, prior to policy <span class="target" id="index-0-policy:CMP0113"></span><a class="reference internal" href="CMP0113.html#policy:CMP0113" title="CMP0113"><code class="xref cmake cmake-policy docutils literal notranslate"><span class="pre">CMP0113</span></code></a>, the step targets generated |
| by <a class="reference internal" href="../manual/cmake-generators.7.html#makefile-generators"><span class="std std-ref">Makefile Generators</span></a> also contain all the custom commands |
| on which their step depends. This can lead to repeated execution of |
| those steps even in serial builds.</p> |
| </li> |
| </ul> |
| <p>In CMake 3.19 and above, the <span class="target" id="index-1-module:ExternalProject"></span><a class="reference internal" href="../module/ExternalProject.html#module:ExternalProject" title="ExternalProject"><code class="xref cmake cmake-module docutils literal notranslate"><span class="pre">ExternalProject</span></code></a> module prefers |
| a revised design to address these problems:</p> |
| <ul> |
| <li><p>Each step is classified as "independent" if it does not depend |
| on other targets named by the <span class="target" id="index-4-command:externalproject_add"></span><a class="reference internal" href="../module/ExternalProject.html#command:externalproject_add" title="externalproject_add"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">ExternalProject_Add()</span></code></a> <code class="docutils literal notranslate"><span class="pre">DEPENDS</span></code>. |
| The predefined steps are automatically classified by default:</p> |
| <ul class="simple"> |
| <li><p>The <code class="docutils literal notranslate"><span class="pre">download</span></code>, <code class="docutils literal notranslate"><span class="pre">update</span></code>, and <code class="docutils literal notranslate"><span class="pre">patch</span></code> steps are independent.</p></li> |
| <li><p>The <code class="docutils literal notranslate"><span class="pre">configure</span></code>, <code class="docutils literal notranslate"><span class="pre">build</span></code>, <code class="docutils literal notranslate"><span class="pre">test</span></code>, and <code class="docutils literal notranslate"><span class="pre">install</span></code> steps are not.</p></li> |
| </ul> |
| <p>For custom steps, the <span class="target" id="index-0-command:externalproject_add_step"></span><a class="reference internal" href="../module/ExternalProject.html#command:externalproject_add_step" title="externalproject_add_step"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">ExternalProject_Add_Step()</span></code></a> command provides |
| an <code class="docutils literal notranslate"><span class="pre">INDEPENDENT</span></code> option to mark them as independent. It is an error to |
| mark a step as independent if it depends on other steps that are not. Note |
| that this use of the term "independent" refers only to independence from |
| external targets and is orthogonal to a step's dependencies on other steps.</p> |
| </li> |
| <li><p>Step targets created by the <span class="target" id="index-5-command:externalproject_add"></span><a class="reference internal" href="../module/ExternalProject.html#command:externalproject_add" title="externalproject_add"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">ExternalProject_Add()</span></code></a> <code class="docutils literal notranslate"><span class="pre">STEP_TARGETS</span></code> |
| option or the <span class="target" id="index-1-command:externalproject_add_step"></span><a class="reference internal" href="../module/ExternalProject.html#command:externalproject_add_step" title="externalproject_add_step"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">ExternalProject_Add_Step()</span></code></a> function are now |
| independent if and only if their steps are marked as independent. |
| The <span class="target" id="index-6-command:externalproject_add"></span><a class="reference internal" href="../module/ExternalProject.html#command:externalproject_add" title="externalproject_add"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">ExternalProject_Add()</span></code></a> <code class="docutils literal notranslate"><span class="pre">INDEPENDENT_STEP_TARGETS</span></code> option |
| and <span class="target" id="index-2-command:externalproject_add_steptargets"></span><a class="reference internal" href="../module/ExternalProject.html#command:externalproject_add_steptargets" title="externalproject_add_steptargets"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">ExternalProject_Add_StepTargets()</span></code></a> <code class="docutils literal notranslate"><span class="pre">NO_DEPENDS</span></code> option |
| are no longer allowed.</p></li> |
| <li><p>Step targets, when created, are fully responsible for holding the |
| custom commands implementing their steps. The primary target created |
| by <span class="target" id="index-7-command:externalproject_add"></span><a class="reference internal" href="../module/ExternalProject.html#command:externalproject_add" title="externalproject_add"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">ExternalProject_Add()</span></code></a> depends on the step targets, and the |
| step targets depend on each other. The target-level dependencies match |
| the file-level dependencies used by the custom commands for each step.</p> |
| <p>When the <span class="target" id="index-8-command:externalproject_add"></span><a class="reference internal" href="../module/ExternalProject.html#command:externalproject_add" title="externalproject_add"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">ExternalProject_Add()</span></code></a> <code class="docutils literal notranslate"><span class="pre">UPDATE_DISCONNECTED</span></code> or |
| <code class="docutils literal notranslate"><span class="pre">TEST_EXCLUDE_FROM_MAIN</span></code> option is used, or the |
| <span class="target" id="index-2-command:externalproject_add_step"></span><a class="reference internal" href="../module/ExternalProject.html#command:externalproject_add_step" title="externalproject_add_step"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">ExternalProject_Add_Step()</span></code></a> <code class="docutils literal notranslate"><span class="pre">EXCLUDE_FROM_MAIN</span></code> option is used |
| for a custom step, some step targets may be created automatically. |
| These are needed to hold the steps commonly depended upon by the primary |
| target and the disconnected step targets.</p> |
| </li> |
| </ul> |
| <p>Policy <code class="docutils literal notranslate"><span class="pre">CMP0114</span></code> provides compatibility for projects that have not been |
| updated to expect the new behavior. The <code class="docutils literal notranslate"><span class="pre">OLD</span></code> behavior for this policy |
| is to use the above-documented behavior from 3.18 and below. The <code class="docutils literal notranslate"><span class="pre">NEW</span></code> |
| behavior for this policy is to use the above-documented behavior preferred |
| by 3.19 and above.</p> |
| <p>This policy was introduced in CMake version 3.19. CMake version |
| 3.23.1 warns when the policy is not set and uses <code class="docutils literal notranslate"><span class="pre">OLD</span></code> behavior. |
| 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.</p> |
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