install,export: Maybe transform OBJECT libraries to INTERFACE libraries

Teach the `install` and `export` commands to support installing and
exporting `OBJECT` libraries without their object files.  Transform
them to `INTERFACE` libraries in such cases.

For `install(TARGETS)`, activate this when no destination for the object
files is specified.  For `export`, activate this only under Xcode with
multiple architectures when we have no well-defined object file
locations to give to clients.

1 files changed, 14 insertions, 0 deletions

diff --git a/Tests/ExportImport/Import/A/CMakeLists.txt b/Tests/ExportImport/Import/A/CMakeLists.txt
index 01960ea..6d16cb7 100644
--- a/Tests/ExportImport/Import/A/CMakeLists.txt
+++ b/Tests/ExportImport/Import/A/CMakeLists.txt
@@ -229,6 +229,8 @@ add_library(imp_lib1b STATIC imp_lib1.c)
 target_link_libraries(imp_lib1b bld_testLib2)
 
 if(NOT CMAKE_GENERATOR STREQUAL "Xcode" OR NOT CMAKE_OSX_ARCHITECTURES MATCHES "[;$]")
+  set(bld_objlib_type OBJECT_LIBRARY)
+
   # Create a executable that is using objects imported from the install tree
   add_executable(imp_testLib8 imp_testLib8.c $<TARGET_OBJECTS:exp_testLib8>)
 
@@ -236,6 +238,18 @@ if(NOT CMAKE_GENERATOR STREQUAL "Xcode" OR NOT CMAKE_OSX_ARCHITECTURES MATCHES "
     # Create a executable that is using objects imported from the build tree
     add_executable(imp_testLib8b imp_testLib8.c $<TARGET_OBJECTS:bld_testLib8>)
   endif()
+else()
+  set(bld_objlib_type INTERFACE_LIBRARY)
+endif()
+
+# Check that object libraries were transformed on export as expected.
+get_property(type TARGET exp_testLib9Obj PROPERTY TYPE)
+if(NOT type STREQUAL INTERFACE_LIBRARY)
+  message(FATAL_ERROR "exp_testLib9Obj type is '${type}', not 'INTERFACE_LIBRARY'")
+endif()
+get_property(type TARGET bld_testLib9Obj PROPERTY TYPE)
+if(NOT type STREQUAL "${bld_objlib_type}")
+  message(FATAL_ERROR "bld_testLib9Obj type is '${type}', not '${bld_objlib_type}'")
 endif()
 
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