ALIAS: Add support for add_dependencies for ALIAS targets

The add_dependencies command currently accepts ALIAS targets for
<target-dependencies> which resolve to the referenced target. This further
relaxes the command to accept an ALIAS <target> where the command will
add the dependencies to the target which the alias references.

Help/command/add_dependencies.rst

@@ -35,6 +35,10 @@ transitively in its place since the target itself does not build.
   The command may be called with no dependencies.
   Previously, at least one dependency was required.
 
+.. versionchanged:: 4.5
+  If ``<target>`` is an :ref:`Alias Target <Alias Targets>`, dependencies are
+  added to the target which the alias references.
+
 See Also
 ^^^^^^^^
 

Help/release/dev/alias-transparency.rst

@@ -10,6 +10,9 @@ alias-transparency
   :command:`target_link_directories`, :command:`target_link_libraries`,
   :command:`target_link_options`, :command:`target_precompile_headers`,
   and :command:`target_sources` commands now accept :ref:`Alias Targets`.
-  The commands operate on the target which the alias references.
+  The command operates on the target which the alias references.
+
+* The :command:`add_dependencies` command now accepts :ref:`Alias Targets`.
+  Dependencies are added to the target which the alias references.
 
 * The :prop_tgt:`ALIASED_TARGET` target property is now read-only.

Source/cmAddDependenciesCommand.cxx

@@ -19,12 +19,6 @@ bool cmAddDependenciesCommand(std::vector<std::string> const& args,
 
   cmMakefile& mf = status.GetMakefile();
   std::string const& target_name = args[0];
-  if (mf.IsAlias(target_name)) {
-    mf.IssueMessage(
-      MessageType::FATAL_ERROR,
-      cmStrCat("Cannot add target-level dependencies to alias target \"",
-               target_name, "\".\n"));
-  }
   if (cmTarget* target = mf.FindTargetToUse(target_name)) {
 
     // skip over target_name

Tests/RunCMake/alias_targets/add_dependencies-result.txt

@@ -1 +0,0 @@
-1

Tests/RunCMake/alias_targets/add_dependencies-stderr.txt

@@ -1,5 +0,0 @@
-CMake Error at add_dependencies\.cmake:9 \(add_dependencies\):
-  Cannot add target-level dependencies to alias target "alias"\.
-
-Call Stack \(most recent call first\):
-  CMakeLists\.txt:3 \(include\)

Tests/RunCMake/alias_targets/add_dependencies.cmake

@@ -7,3 +7,8 @@ add_library(bar empty.cpp)
 add_library(alias ALIAS foo)
 
 add_dependencies(alias bar)
+
+get_property(DEPS TARGET foo PROPERTY MANUALLY_ADDED_DEPENDENCIES)
+if(NOT DEPS STREQUAL "bar")
+  message(SEND_ERROR "add_dependencies(): Expected 'bar' as dependency of 'foo' but got: '${DEPS}' instead of 'bar'.")
+endif()