CMake: Clean up docs of deployment variables for 6.3

Clarified the docs that using the deployment variables is for avoiding
hard-coding of specific paths.
Added docs on how to customize the variable defaults
Added example doc snippet demonstrating how to modify the values.
Added upstream doc links where relevant.

Pick-to: 6.3
Fixes: QTBUG-100924
Change-Id: I938dcadd776c8b7019da4709dfced166454a6c92
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>

1 files changed, 49 insertions, 12 deletions

diff --git a/src/corelib/doc/src/cmake/cmake-deploy-variables.qdoc b/src/corelib/doc/src/cmake/cmake-deploy-variables.qdoc
index 4444153243..e693024eb6 100644
--- a/src/corelib/doc/src/cmake/cmake-deploy-variables.qdoc
+++ b/src/corelib/doc/src/cmake/cmake-deploy-variables.qdoc
@@ -45,11 +45,12 @@
 \cmakevariablesince 6.3
 \preliminarycmakevariable
 
-\c{QT_DEPLOY_PREFIX} provides the base directory of the deployment. The other
+\c{QT_DEPLOY_PREFIX} provides the base deployment directory. The other
 \c{QT_DEPLOY_..._DIR} variables should be treated as relative to this location.
 The value of \c{QT_DEPLOY_PREFIX} may be relative or absolute, so projects
 should not assume one or the other in any given situation. A relative path is
-expected to be treated as relative to the current working directory.
+expected to be treated as relative to the current working directory, as seen
+by the build tool (ninja, make, and so on) at install time.
 
 The default value is \c{$ENV{DESTDIR}${CMAKE_INSTALL_PREFIX}}, which is the
 base location CMake uses during installation. If that evaluates to an empty
@@ -59,6 +60,13 @@ fallback logic ensures that projects can assume \c{QT_DEPLOY_PREFIX} will not
 be an empty string, so it can safely be used as part of a path like
 \c{${QT_DEPLOY_PREFIX}/${QT_DEPLOY_BIN_DIR}}.
 
+To change the value of \c QT_DEPLOY_PREFIX, the project can be configured
+with a custom \l CMAKE_INSTALL_PREFIX as described in
+\l {Command Line cmake invocation}.
+
+The \l DESTDIR environment variable can also be used to modify the final
+installation, and thus deployment, location.
+
 Projects should rarely need to use this variable. In typical scenarios, deploy
 scripts should assume that the working directory is already set to the base
 install location and just use the prefix-relative \c{QT_DEPLOY_..._DIR}
@@ -82,7 +90,7 @@ variables.
 \cmakevariablesince 6.3
 \preliminarycmakevariable
 
-Projects should use \c QT_DEPLOY_BIN_DIR in their deploy scripts instead of
+Projects should use \c QT_DEPLOY_BIN_DIR in their deploy scripts to avoid
 hard-coding a particular directory in which to deploy the following types of
 binaries:
 
@@ -91,8 +99,12 @@ binaries:
 \li DLLs on Windows.
 \endlist
 
-\c QT_DEPLOY_BIN_DIR defaults to the value of \c${CMAKE_INSTALL_BINDIR}, which
-is provided by CMake's \l{GNUInstallDirs} module.
+\c QT_DEPLOY_BIN_DIR defaults to the value of \c${CMAKE_INSTALL_BINDIR}
+(usually \c{bin}), which is provided by CMake's \l{GNUInstallDirs} module.
+To change the value of \c QT_DEPLOY_BIN_DIR, ensure that the project sets
+\c{CMAKE_INSTALL_BINDIR} before the \c Core package is found.
+
+The \c QT_DEPLOY_BIN_DIR path is relative to \l{QT_DEPLOY_PREFIX}.
 
 This variable is not meaningful when deploying into a macOS app bundle and
 should not be used for that scenario.
@@ -119,7 +131,7 @@ should not be used for that scenario.
 \cmakevariablesince 6.3
 \preliminarycmakevariable
 
-Projects should use \c QT_DEPLOY_LIB_DIR in their deploy scripts instead of
+Projects should use \c QT_DEPLOY_LIB_DIR in their deploy scripts to avoid
 hard-coding a particular directory in which to deploy the following types of
 binaries:
 
@@ -128,12 +140,21 @@ binaries:
 \li Import libraries on Windows.
 \endlist
 
-\c QT_DEPLOY_LIB_DIR defaults to the value of \c${CMAKE_INSTALL_LIBDIR}, which
-is provided by CMake's \l{GNUInstallDirs} module.
+\c QT_DEPLOY_LIB_DIR defaults to the value of \c${CMAKE_INSTALL_LIBDIR}
+(usually \c{lib} or \c{lib64}), which is provided by
+CMake's \l{GNUInstallDirs} module.
+To change the value of \c QT_DEPLOY_LIB_DIR, ensure that the project sets
+\c{CMAKE_INSTALL_LIBDIR} before the \c Core package is found.
+
+The \c QT_DEPLOY_LIB_DIR path is relative to \l{QT_DEPLOY_PREFIX}.
 
 This variable is not meaningful when deploying into a macOS app bundle and
 should not be used for that scenario.
 
+\section1 Example
+
+\include cmake-deploy-modified-variable-values.qdocinc
+
 \sa QT_DEPLOY_SUPPORT, QT_DEPLOY_PREFIX, QT_DEPLOY_BIN_DIR,
     QT_DEPLOY_PLUGINS_DIR, QT_DEPLOY_QML_DIR
 */
@@ -152,16 +173,24 @@ should not be used for that scenario.
 \cmakevariablesince 6.3
 \preliminarycmakevariable
 
-Projects should use \c QT_DEPLOY_PLUGINS_DIR in their deploy scripts instead of
+Projects should use \c QT_DEPLOY_PLUGINS_DIR in their deploy scripts to avoid
 hard-coding a particular directory under which to deploy plugins.
 
-\c QT_DEPLOY_PLUGINS_DIR defaults to the value \c{plugins}.
+\c QT_DEPLOY_PLUGINS_DIR defaults to the value \c{plugins}. To change the value
+of \c QT_DEPLOY_PLUGINS_DIR, set it in the project deployment script
+before \c QT_DEPLOY_SUPPORT is included.
+
+The \c QT_DEPLOY_PLUGINS_DIR path is relative to \l{QT_DEPLOY_PREFIX}.
 
 This variable is not meaningful when deploying into a macOS app bundle and
 should not be used for that scenario. Apple's macOS app bundle guidelines
 require all plugins to be deployed to the \c{PlugIns} subdirectory of the
 bundle contents.
 
+\section1 Example
+
+\include cmake-deploy-modified-variable-values.qdocinc
+
 \sa QT_DEPLOY_SUPPORT, QT_DEPLOY_PREFIX, QT_DEPLOY_BIN_DIR, QT_DEPLOY_LIB_DIR,
     QT_DEPLOY_QML_DIR
 */
@@ -180,10 +209,14 @@ bundle contents.
 \cmakevariablesince 6.3
 \preliminarycmakevariable
 
-Projects should use \c QT_DEPLOY_QML_DIR in their deploy scripts instead of
+Projects should use \c QT_DEPLOY_QML_DIR in their deploy scripts to avoid
 hard-coding a particular directory under which to deploy QML modules.
 
-\c QT_DEPLOY_QML_DIR defaults to the value \c{qml}.
+\c QT_DEPLOY_QML_DIR defaults to the value \c{qml}. To change the value
+of \c QT_DEPLOY_QML_DIR, set it in the project deployment script
+before \c QT_DEPLOY_SUPPORT is included.
+
+The \c QT_DEPLOY_QML_DIR path is relative to \l{QT_DEPLOY_PREFIX}.
 
 This variable is not meaningful when deploying into a macOS app bundle and
 should not be used for that scenario. Apple's macOS app bundle guidelines
@@ -192,6 +225,10 @@ bundle contents, and all other non-binary files should generally be under the
 \c{Resources} subdirectory. The different parts of a QML module therefore need
 to be deployed to different locations within the app bundle.
 
+\section1 Example
+
+\include cmake-deploy-modified-variable-values.qdocinc
+
 \sa QT_DEPLOY_SUPPORT, QT_DEPLOY_PREFIX, QT_DEPLOY_BIN_DIR, QT_DEPLOY_LIB_DIR,
     QT_DEPLOY_PLUGINS_DIR
 */