productbuild: Restore CPACK_PACKAGEMAKER_CHOICES variable

In 2a8df7e7db (productbuild: Don't write rootVolumeOnly attribute if
writing domains, 2022-03-21), the variable holding the main contents
of the distribution.dist XML file was renamed from
CPACK_PACKAGEMAKER_CHOICES to CPACK_APPLE_PKG_INSTALLER_CONTENT.
This reflected the fact that the PackageMaker generator is deprecated.
The new variable also includes more details than the old one held.
Some projects were relying on the old variable name, so we need to still
set that to the same contents as it would have previously provided.

Neither of these variables were previously documented, but the older
variable was mentioned in enough semi-official places that it essentially
became semi-supported. Document both variables and highlight that the
older one is deprecated.

Fixes: #23467

3 files changed, 108 insertions, 21 deletions

diff --git a/Help/cpack_gen/productbuild.rst b/Help/cpack_gen/productbuild.rst
index 26e0782..48a9b44 100644
--- a/Help/cpack_gen/productbuild.rst
+++ b/Help/cpack_gen/productbuild.rst
@@ -203,3 +203,47 @@ installer.
 
  Does the same as :variable:`CPACK_PRODUCTBUILD_BACKGROUND_UTI` option,
  but for the dark theme.
+
+Distribution XML Template
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+CPack uses a template file to generate the ``distribution.dist`` file used
+internally by this package generator. Ordinarily, CMake provides the template
+file, but projects may supply their own by placing a file called
+``CPack.distribution.dist.in`` in one of the directories listed in the
+:variable:`CMAKE_MODULE_PATH` variable. CPack will then pick up the project's
+template file instead of using its own.
+
+The ``distribution.dist`` file is generated by performing substitutions
+similar to the :command:`configure_file` command. Any variable set when
+CPack runs will be available for substitution using the usual ``@...@``
+form. The following variables are also set internally and made available for
+substitution:
+
+``CPACK_RESOURCE_FILE_LICENSE_NOPATH``
+  Same as :variable:`CPACK_RESOURCE_FILE_LICENSE` except without the path.
+  The named file will be available in the same directory as the generated
+  ``distribution.dist`` file.
+
+``CPACK_RESOURCE_FILE_README_NOPATH``
+  Same as :variable:`CPACK_RESOURCE_FILE_README` except without the path.
+  The named file will be available in the same directory as the generated
+  ``distribution.dist`` file.
+
+``CPACK_RESOURCE_FILE_WELCOME_NOPATH``
+  Same as :variable:`CPACK_RESOURCE_FILE_WELCOME` except without the path.
+  The named file will be available in the same directory as the generated
+  ``distribution.dist`` file.
+
+``CPACK_APPLE_PKG_INSTALLER_CONTENT``
+  .. versionadded:: 3.23
+
+  This contains all the XML elements that specify installer-wide options
+  (including domain details), default backgrounds and the choices outline.
+
+``CPACK_PACKAGEMAKER_CHOICES``
+  .. deprecated:: 3.23
+
+  This contains only the XML elements that specify the default backgrounds
+  and the choices outline. It does not include the installer-wide options or
+  any domain details. Use ``CPACK_APPLE_PKG_INSTALLER_CONTENT`` instead.
diff --git a/Help/release/3.23.rst b/Help/release/3.23.rst
index 2febbec..47c4243 100644
--- a/Help/release/3.23.rst
+++ b/Help/release/3.23.rst
@@ -185,6 +185,13 @@ CPack
   :variable:`CPACK_PRODUCTBUILD_IDENTIFIER`, used to customize the unique
   product identifier associated with the product.
 
+* The ``CPack.distribution.dist.in`` template used by the
+  :cpack_gen:`CPack productbuild Generator` and
+  :cpack_gen:`CPack PackageMaker Generator` was updated to use a new
+  ``CPACK_APPLE_PKG_INSTALLER_CONTENT`` variable for its main content.
+  This replaced the previously undocumented and now deprecated
+  ``CPACK_PACKAGEMAKER_CHOICES`` variable.
+
 * The :cpack_gen:`CPack IFW Generator` gained the new
   :variable:`CPACK_IFW_ARCHIVE_FORMAT` and
   :variable:`CPACK_IFW_ARCHIVE_COMPRESSION` variables for setting the
@@ -230,6 +237,15 @@ Deprecated and Removed Features
 
 * The :manual:`cpack(1)` undocumented ``OSXX11`` generator has been removed.
 
+* The previously undocumented ``CPACK_PACKAGEMAKER_CHOICES`` variable used in
+  the ``CPack.distribution.dist.in`` template has been replaced by a new
+  ``CPACK_APPLE_PKG_INSTALLER_CONTENT`` variable. This only affects projects
+  that were providing their own custom ``CPack.distribution.dist.in`` template
+  file, but still relied on ``CPACK_PACKAGEMAKER_CHOICES`` being set. Those
+  custom template files should be updated to use
+  ``CPACK_APPLE_PKG_INSTALLER_CONTENT`` instead, or to fully define all the
+  template file's contents without relying on substitution of either variable.
+
 Other Changes
 =============
 
@@ -282,3 +298,14 @@ Changes made since CMake 3.23.0 include the following.
 * The :prop_tgt:`HEADER_SETS` and :prop_tgt:`INTERFACE_HEADER_SETS` target
   properties added in CMake 3.23.0 are now read-only records of the header
   sets created by the :command:`target_sources` command.
+
+3.23.2
+------
+
+* The ``CPACK_PACKAGEMAKER_CHOICES`` variable used in the
+  ``CPack.distribution.dist.in`` template file was replaced by a new
+  ``CPACK_APPLE_PKG_INSTALLER_CONTENT`` variable in CMake 3.23.0.
+  This broke projects that provided their own template file but still
+  expected the ``CPACK_PACKAGEMAKER_CHOICES`` variable to be defined.
+  The old ``CPACK_PACKAGEMAKER_CHOICES`` variable is now also set to the
+  same content as it was before, but it is formally deprecated.
diff --git a/Source/CPack/cmCPackPKGGenerator.cxx b/Source/CPack/cmCPackPKGGenerator.cxx
index 2a14ccf..7b9f6cf 100644
--- a/Source/CPack/cmCPackPKGGenerator.cxx
+++ b/Source/CPack/cmCPackPKGGenerator.cxx
@@ -123,7 +123,9 @@ void cmCPackPKGGenerator::WriteDistributionFile(const char* metapackageFile,
   std::ostringstream xContents;
   cmXMLWriter xout(xContents, 1);
 
-  // Installer-wide options
+  // Installer-wide options and domains. These need to be separate from the
+  // choices and background elements added further below so that we can
+  // preserve backward compatibility.
   xout.StartElement("options");
   xout.Attribute("allow-external-scripts", "no");
   xout.Attribute("customize", "allow");
@@ -131,55 +133,69 @@ void cmCPackPKGGenerator::WriteDistributionFile(const char* metapackageFile,
     xout.Attribute("rootVolumeOnly", "false");
   }
   xout.EndElement();
+  this->CreateDomains(xout);
+
+  // In order to preserve backward compatibility, all elements added below
+  // here need to be made available in a variable named
+  // CPACK_PACKAGEMAKER_CHOICES. The above elements are new and only appear
+  // in the CPACK_APPLE_PKG_INSTALLER_CONTENT variable, which is a superset
+  // of what CPACK_PACKAGEMAKER_CHOICES used to provide. The renaming reflects
+  // the fact that CMake has deprecated the PackageMaker generator.
 
   // Create the choice outline, which provides a tree-based view of
   // the components in their groups.
-  xout.StartElement("choices-outline");
+  std::ostringstream choiceOut;
+  cmXMLWriter xChoiceOut(choiceOut, 1);
+  xChoiceOut.StartElement("choices-outline");
 
   // Emit the outline for the groups
   for (auto const& group : this->ComponentGroups) {
     if (group.second.ParentGroup == nullptr) {
-      CreateChoiceOutline(group.second, xout);
+      CreateChoiceOutline(group.second, xChoiceOut);
     }
   }
 
   // Emit the outline for the non-grouped components
   for (auto const& comp : this->Components) {
     if (!comp.second.Group) {
-      xout.StartElement("line");
-      xout.Attribute("choice", comp.first + "Choice");
-      xout.Content(""); // Avoid self-closing tag.
-      xout.EndElement();
+      xChoiceOut.StartElement("line");
+      xChoiceOut.Attribute("choice", comp.first + "Choice");
+      xChoiceOut.Content(""); // Avoid self-closing tag.
+      xChoiceOut.EndElement();
     }
   }
   if (!this->PostFlightComponent.Name.empty()) {
-    xout.StartElement("line");
-    xout.Attribute("choice", PostFlightComponent.Name + "Choice");
-    xout.Content(""); // Avoid self-closing tag.
-    xout.EndElement();
+    xChoiceOut.StartElement("line");
+    xChoiceOut.Attribute("choice", PostFlightComponent.Name + "Choice");
+    xChoiceOut.Content(""); // Avoid self-closing tag.
+    xChoiceOut.EndElement();
   }
-  xout.EndElement(); // choices-outline>
+  xChoiceOut.EndElement(); // choices-outline>
 
   // Create the actual choices
   for (auto const& group : this->ComponentGroups) {
-    CreateChoice(group.second, xout);
+    CreateChoice(group.second, xChoiceOut);
   }
   for (auto const& comp : this->Components) {
-    CreateChoice(comp.second, xout);
+    CreateChoice(comp.second, xChoiceOut);
   }
 
   if (!this->PostFlightComponent.Name.empty()) {
-    CreateChoice(PostFlightComponent, xout);
+    CreateChoice(PostFlightComponent, xChoiceOut);
   }
 
-  this->CreateDomains(xout);
-
-  // default background
-  this->CreateBackground(nullptr, metapackageFile, genName, xout);
+  // default background. These are not strictly part of the choices, but they
+  // must be included in CPACK_PACKAGEMAKER_CHOICES to preserve backward
+  // compatibility.
+  this->CreateBackground(nullptr, metapackageFile, genName, xChoiceOut);
   // Dark Aqua
-  this->CreateBackground("darkAqua", metapackageFile, genName, xout);
+  this->CreateBackground("darkAqua", metapackageFile, genName, xChoiceOut);
 
-  this->SetOption("CPACK_APPLE_PKG_INSTALLER_CONTENT", xContents.str());
+  // Provide the content for substitution into the template. Support both the
+  // old and new variables.
+  this->SetOption("CPACK_PACKAGEMAKER_CHOICES", choiceOut.str());
+  this->SetOption("CPACK_APPLE_PKG_INSTALLER_CONTENT",
+                  cmStrCat(xContents.str(), "    ", choiceOut.str()));
 
   // Create the distribution.dist file in the metapackage to turn it
   // into a distribution package.