Add directory property to list imported targets

Model the change after commit cbca65826c (Add directory property to list
buildsystem targets, 2016-09-19, v3.7.0-rc1~79^2~1).

Fixes: #22291

Help/manual/cmake-properties.7.rst

@@ -74,6 +74,7 @@ Properties on Directories
    /prop_dir/DEFINITIONS
    /prop_dir/EXCLUDE_FROM_ALL
    /prop_dir/IMPLICIT_DEPENDS_INCLUDE_TRANSFORM
+   /prop_dir/IMPORTED_TARGETS
    /prop_dir/INCLUDE_DIRECTORIES
    /prop_dir/INCLUDE_REGULAR_EXPRESSION
    /prop_dir/INTERPROCEDURAL_OPTIMIZATION

Help/prop_dir/BUILDSYSTEM_TARGETS.rst

@@ -11,3 +11,5 @@ and :command:`add_custom_target` commands.  The list does not include any
 :ref:`Interface Libraries`.  Each entry in the list is the logical name
 of a target, suitable to pass to the :command:`get_property` command
 ``TARGET`` option.
+
+See also the :prop_dir:`IMPORTED_TARGETS` directory property.

Help/prop_dir/IMPORTED_TARGETS.rst

@@ -0,0 +1,14 @@
+IMPORTED_TARGETS
+----------------
+
+.. versionadded:: 3.21
+
+This read-only directory property contains a
+:ref:`semicolon-separated list <CMake Language Lists>` of
+:ref:`Imported Targets` added in the directory by calls to the
+:command:`add_library` and :command:`add_executable` commands.
+Each entry in the list is the logical name of a target, suitable
+to pass to the :command:`get_property` command ``TARGET`` option
+when called in the same directory.
+
+See also the :prop_dir:`BUILDSYSTEM_TARGETS` directory property.

Help/release/dev/dir-IMPORTED_TARGETS.rst

@@ -0,0 +1,6 @@
+dir-IMPORTED_TARGETS
+--------------------
+
+* The :prop_dir:`IMPORTED_TARGETS` directory property was added to
+  get a list of :ref:`Imported Targets` created in the current
+  directory.

Source/cmStateDirectory.cxx

@@ -8,7 +8,9 @@
 #include <vector>
 
 #include <cm/iterator>
+#include <cm/string_view>
 #include <cmext/algorithm>
+#include <cmext/string_view>
 
 #include "cmAlgorithms.h"
 #include "cmProperty.h"
@@ -475,6 +477,10 @@ cmProp cmStateDirectory::GetProperty(const std::string& prop, bool chain) const
     output = cmJoin(this->DirectoryState->NormalTargetNames, ";");
     return &output;
   }
+  if (prop == "IMPORTED_TARGETS"_s) {
+    output = cmJoin(this->DirectoryState->ImportedTargetNames, ";");
+    return &output;
+  }
 
   if (prop == "LISTFILE_STACK") {
     std::vector<std::string> listFiles;

Tests/RunCMake/get_property/directory_properties-stderr.txt

@@ -12,6 +12,10 @@ get_directory_property: -->CustomTop;InterfaceTop<--
 get_property: -->CustomTop;InterfaceTop<--
 get_directory_property: -->CustomSub;InterfaceSub<--
 get_property: -->CustomSub;InterfaceSub<--
+get_directory_property: -->Imported1Top;Imported2Top<--
+get_property: -->Imported1Top;Imported2Top<--
+get_directory_property: -->Imported1Sub;Imported2Sub<--
+get_property: -->Imported1Sub;Imported2Sub<--
 get_directory_property: -->[^<;]*/Tests/RunCMake/get_property/directory_properties-build<--
 get_property: -->[^<;]*/Tests/RunCMake/get_property/directory_properties-build<--
 get_directory_property: -->[^<;]*/RunCMake/get_property<--

Tests/RunCMake/get_property/directory_properties.cmake

@@ -18,11 +18,16 @@ add_custom_target(CustomTop)
 add_library(InterfaceTop INTERFACE)
 add_library(my::InterfaceTop ALIAS InterfaceTop)
 
+add_library(Imported1Top INTERFACE IMPORTED)
+add_library(Imported2Top INTERFACE IMPORTED)
+
 add_subdirectory(directory_properties)
 check_directory_property("${CMAKE_CURRENT_SOURCE_DIR}" SUBDIRECTORIES)
 check_directory_property("${CMAKE_CURRENT_SOURCE_DIR}/directory_properties" SUBDIRECTORIES)
 check_directory_property("${CMAKE_CURRENT_SOURCE_DIR}" BUILDSYSTEM_TARGETS)
 check_directory_property("${CMAKE_CURRENT_SOURCE_DIR}/directory_properties" BUILDSYSTEM_TARGETS)
+check_directory_property("${CMAKE_CURRENT_SOURCE_DIR}" IMPORTED_TARGETS)
+check_directory_property("${CMAKE_CURRENT_SOURCE_DIR}/directory_properties" IMPORTED_TARGETS)
 
 check_directory_property("${CMAKE_CURRENT_SOURCE_DIR}" BINARY_DIR)
 check_directory_property("${CMAKE_CURRENT_SOURCE_DIR}" SOURCE_DIR)

Tests/RunCMake/get_property/directory_properties/CMakeLists.txt

@@ -5,5 +5,8 @@ add_custom_target(CustomSub)
 add_library(InterfaceSub INTERFACE)
 add_library(my::InterfaceSub ALIAS InterfaceSub)
 
+add_library(Imported1Sub INTERFACE IMPORTED)
+add_library(Imported2Sub INTERFACE IMPORTED)
+
 add_test(Sub/test1 COMMAND "${CMAKE_COMMAND}" -E echo "Sub/test1")
 add_test(Sub/test2 COMMAND "${CMAKE_COMMAND}" -E echo "Sub/test2")