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.

8 files changed, 34 insertions, 17 deletions

diff --git a/Tests/ExportImport/Export/CMakeLists.txt b/Tests/ExportImport/Export/CMakeLists.txt
index eeae3f0..4f663f6 100644
--- a/Tests/ExportImport/Export/CMakeLists.txt
+++ b/Tests/ExportImport/Export/CMakeLists.txt
@@ -83,11 +83,13 @@ set_property(TARGET testLib7 PROPERTY OUTPUT_NAME testLib7-$<CONFIG>)
 add_library(testLib8 OBJECT testLib8A.c testLib8B.c sub/testLib8C.c)
 
 if(NOT CMAKE_GENERATOR STREQUAL "Xcode" OR NOT CMAKE_OSX_ARCHITECTURES MATCHES "[;$]")
-  set(maybe_testLib8 testLib8)
+  set(maybe_OBJECTS_DESTINATION OBJECTS DESTINATION $<1:lib>)
 else()
-  set(maybe_testLib8 "")
+  set(maybe_OBJECTS_DESTINATION "")
 endif()
 
+add_library(testLib9Obj OBJECT testLib9Obj.c)
+
 # Test using the target_link_libraries command to set the
 # LINK_INTERFACE_LIBRARIES* properties.  We construct two libraries
 # providing the same two symbols.  In each library one of the symbols
@@ -483,7 +485,7 @@ install(
   TARGETS
   testExe1 testLib1 testLib2 testExe2 testLib3 testLib4 testExe3 testExe4
   testExe2lib testLib4lib testLib4libdbg testLib4libopt
-  testLib6 testLib7 ${maybe_testLib8}
+  testLib6 testLib7 testLib8
   testLibCycleA testLibCycleB
   testLibNoSONAME
   cmp0022NEW cmp0022OLD
@@ -492,10 +494,15 @@ install(
   RUNTIME DESTINATION $<1:bin>
   LIBRARY DESTINATION $<1:lib> NAMELINK_SKIP
   ARCHIVE DESTINATION $<1:lib>
-  OBJECTS DESTINATION $<1:lib>
+  ${maybe_OBJECTS_DESTINATION}
   FRAMEWORK DESTINATION Frameworks
   BUNDLE DESTINATION Applications
   )
+install(
+  TARGETS
+  testLib9Obj
+  EXPORT exp
+  )
 if (APPLE)
   file(COPY testLib4.h DESTINATION ${CMAKE_CURRENT_BINARY_DIR}/testLib4.framework/Headers)
   file(COPY testLib4.h DESTINATION ${CMAKE_CURRENT_BINARY_DIR}/Debug/testLib4.framework/Headers)
@@ -545,7 +552,8 @@ export(TARGETS testExe1 testLib1 testLib2 testLib3
   FILE ExportBuildTree.cmake
   )
 export(TARGETS testExe2 testLib4 testLib5 testLib6 testLib7 testExe3 testExe4 testExe2lib
-  ${maybe_testLib8}
+  testLib8
+  testLib9Obj
   testLib4lib testLib4libdbg testLib4libopt
   testLibCycleA testLibCycleB
   testLibNoSONAME
diff --git a/Tests/ExportImport/Export/testLib9Obj.c b/Tests/ExportImport/Export/testLib9Obj.c
new file mode 100644
index 0000000..6a13e48
--- /dev/null
+++ b/Tests/ExportImport/Export/testLib9Obj.c
@@ -0,0 +1,4 @@
+int testLib9Obj(void)
+{
+  return 0;
+}
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()
 
 #-----------------------------------------------------------------------------
diff --git a/Tests/RunCMake/ObjectLibrary/ExportNotSupported-result.txt b/Tests/RunCMake/ObjectLibrary/ExportNotSupported-result.txt
deleted file mode 100644
index d00491f..0000000
--- a/Tests/RunCMake/ObjectLibrary/ExportNotSupported-result.txt
+++ /dev/null
@@ -1 +0,0 @@
-1
diff --git a/Tests/RunCMake/ObjectLibrary/ExportNotSupported-stderr.txt b/Tests/RunCMake/ObjectLibrary/ExportNotSupported-stderr.txt
deleted file mode 100644
index 5420159..0000000
--- a/Tests/RunCMake/ObjectLibrary/ExportNotSupported-stderr.txt
+++ /dev/null
@@ -1,5 +0,0 @@
-CMake Error at ExportNotSupported.cmake:[0-9]+ \(export\):
-  export given OBJECT library "A" which may not be exported under Xcode with
-  multiple architectures.
-Call Stack \(most recent call first\):
-  CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/ObjectLibrary/ExportNotSupported.cmake b/Tests/RunCMake/ObjectLibrary/ExportNotSupported.cmake
deleted file mode 100644
index a3f104e..0000000
--- a/Tests/RunCMake/ObjectLibrary/ExportNotSupported.cmake
+++ /dev/null
@@ -1,2 +0,0 @@
-add_library(A OBJECT a.c)
-export(TARGETS A FILE AExport.cmake)
diff --git a/Tests/RunCMake/ObjectLibrary/InstallNotSupported-stderr.txt b/Tests/RunCMake/ObjectLibrary/InstallNotSupported-stderr.txt
index 35a0e4f..a7004c1 100644
--- a/Tests/RunCMake/ObjectLibrary/InstallNotSupported-stderr.txt
+++ b/Tests/RunCMake/ObjectLibrary/InstallNotSupported-stderr.txt
@@ -1,5 +1,5 @@
 CMake Error at InstallNotSupported.cmake:[0-9]+ \(install\):
-  install TARGETS given OBJECT library "A" which may not be installed under
-  Xcode with multiple architectures.
+  install TARGETS given OBJECT library "A" whose objects may not be installed
+  under Xcode with multiple architectures.
 Call Stack \(most recent call first\):
   CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/ObjectLibrary/RunCMakeTest.cmake b/Tests/RunCMake/ObjectLibrary/RunCMakeTest.cmake
index b8eed73..5c9dd65 100644
--- a/Tests/RunCMake/ObjectLibrary/RunCMakeTest.cmake
+++ b/Tests/RunCMake/ObjectLibrary/RunCMakeTest.cmake
@@ -6,14 +6,13 @@ run_cmake(BadSourceExpression3)
 run_cmake(BadObjSource1)
 run_cmake(BadObjSource2)
 if(RunCMake_GENERATOR STREQUAL "Xcode" AND "$ENV{CMAKE_OSX_ARCHITECTURES}" MATCHES "[;$]")
-  run_cmake(ExportNotSupported)
   run_cmake(ImportNotSupported)
   run_cmake(InstallNotSupported)
 else()
-  run_cmake(Export)
   run_cmake(Import)
   run_cmake(Install)
 endif()
+run_cmake(Export)
 run_cmake(LinkObjLHS)
 run_cmake(LinkObjRHS1)
 run_cmake(LinkObjRHS2)