Genex: Allow TARGET_OBJECTS to be used everywhere

Previously the `TARGET_OBJECTS` generator expression was limited
only to use in a buildsystem context so that Xcode's placeholders
in object file paths can be evaluated.  Lift this restriction so
that the expression can at least be used in most settings.

Co-Author: Brad King <brad.king@kitware.com>

4 files changed, 50 insertions, 0 deletions

diff --git a/Tests/GeneratorExpression/CMakeLists.txt b/Tests/GeneratorExpression/CMakeLists.txt
index adc87cd..8ac3419 100644
--- a/Tests/GeneratorExpression/CMakeLists.txt
+++ b/Tests/GeneratorExpression/CMakeLists.txt
@@ -292,3 +292,19 @@ set(CMP0044_TYPE NEW)
 add_subdirectory(CMP0044 ${CMAKE_BINARY_DIR}/CMP0044-NEW)
 set(CMP0044_TYPE OLD)
 add_subdirectory(CMP0044 ${CMAKE_BINARY_DIR}/CMP0044-OLD)
+
+if(NOT CMAKE_GENERATOR STREQUAL Xcode OR NOT CMAKE_OSX_ARCHITECTURES MATCHES "[;$]")
+  add_library(objlib OBJECT objlib1.c objlib2.c)
+  file(GENERATE
+    OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/objlib_files_$<CONFIGURATION>"
+    CONTENT "$<JOIN:$<TARGET_OBJECTS:objlib>,\n>\n"
+  )
+
+  add_custom_target(check_object_files ALL
+    COMMAND ${CMAKE_COMMAND}
+      "-DOBJLIB_LISTFILE=${CMAKE_CURRENT_BINARY_DIR}/objlib_files_$<CONFIGURATION>"
+      -DEXPECTED_NUM_OBJECTFILES=2
+      -P "${CMAKE_CURRENT_SOURCE_DIR}/check_object_files.cmake"
+    DEPENDS objlib
+  )
+endif()
diff --git a/Tests/GeneratorExpression/check_object_files.cmake b/Tests/GeneratorExpression/check_object_files.cmake
new file mode 100644
index 0000000..cfccd29
--- /dev/null
+++ b/Tests/GeneratorExpression/check_object_files.cmake
@@ -0,0 +1,26 @@
+
+if (NOT EXISTS ${OBJLIB_LISTFILE})
+  message(SEND_ERROR "Object listing file \"${OBJLIB_LISTFILE}\" not found!")
+endif()
+
+file(STRINGS ${OBJLIB_LISTFILE} objlib_files ENCODING UTF-8)
+
+list(LENGTH objlib_files num_objectfiles)
+if (NOT EXPECTED_NUM_OBJECTFILES EQUAL num_objectfiles)
+  message(SEND_ERROR "Unexpected number of entries in object list file (${num_objectfiles} instead of ${EXPECTED_NUM_OBJECTFILES})")
+endif()
+
+foreach(objlib_file ${objlib_files})
+  set(file_exists False)
+  if (EXISTS ${objlib_file})
+    set(file_exists True)
+  endif()
+
+  if (NOT file_exists)
+    if(attempts)
+      list(REMOVE_DUPLICATES attempts)
+      set(tried "  Tried ${attempts}")
+    endif()
+    message(SEND_ERROR "File \"${objlib_file}\" does not exist!${tried}")
+  endif()
+endforeach()
diff --git a/Tests/GeneratorExpression/objlib1.c b/Tests/GeneratorExpression/objlib1.c
new file mode 100644
index 0000000..98a95a4
--- /dev/null
+++ b/Tests/GeneratorExpression/objlib1.c
@@ -0,0 +1,4 @@
+
+void objlib1()
+{
+}
diff --git a/Tests/GeneratorExpression/objlib2.c b/Tests/GeneratorExpression/objlib2.c
new file mode 100644
index 0000000..b2c1050
--- /dev/null
+++ b/Tests/GeneratorExpression/objlib2.c
@@ -0,0 +1,4 @@
+
+void objlib2()
+{
+}