Allow OBJECT libraries to be installed, exported, and imported

Teach install() and export() to handle the actual object files.
Disallow this on Xcode with multiple architectures because it
still cannot be cleanly supported there.

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

2 files changed, 16 insertions, 16 deletions

diff --git a/Help/command/add_library.rst b/Help/command/add_library.rst
index af75a39..3a76040 100644
--- a/Help/command/add_library.rst
+++ b/Help/command/add_library.rst
@@ -64,7 +64,7 @@ Imported Libraries
 
 ::
 
-  add_library(<name> <SHARED|STATIC|MODULE|UNKNOWN> IMPORTED
+  add_library(<name> <SHARED|STATIC|MODULE|OBJECT|UNKNOWN> IMPORTED
               [GLOBAL])
 
 An :ref:`IMPORTED library target <Imported Targets>` references a library
@@ -106,10 +106,9 @@ may contain only sources that compile, header files, and other files
 that would not affect linking of a normal library (e.g. ``.txt``).
 They may contain custom commands generating such sources, but not
 ``PRE_BUILD``, ``PRE_LINK``, or ``POST_BUILD`` commands.  Object libraries
-cannot be imported, exported, installed, or linked.  Some native build
-systems may not like targets that have only object files, so consider
-adding at least one real source file to any target that references
-``$<TARGET_OBJECTS:objlib>``.
+cannot be linked.  Some native build systems may not like targets that
+have only object files, so consider adding at least one real source file
+to any target that references ``$<TARGET_OBJECTS:objlib>``.
 
 Alias Libraries
 ^^^^^^^^^^^^^^^
diff --git a/Help/command/install.rst b/Help/command/install.rst
index 70087a4..58438b7 100644
--- a/Help/command/install.rst
+++ b/Help/command/install.rst
@@ -73,7 +73,7 @@ Installing Targets
 ::
 
   install(TARGETS targets... [EXPORT <export-name>]
-          [[ARCHIVE|LIBRARY|RUNTIME|FRAMEWORK|BUNDLE|
+          [[ARCHIVE|LIBRARY|RUNTIME|OBJECTS|FRAMEWORK|BUNDLE|
             PRIVATE_HEADER|PUBLIC_HEADER|RESOURCE]
            [DESTINATION <dir>]
            [PERMISSIONS permissions...]
@@ -86,10 +86,10 @@ Installing Targets
           )
 
 The ``TARGETS`` form specifies rules for installing targets from a
-project.  There are five kinds of target files that may be installed:
-``ARCHIVE``, ``LIBRARY``, ``RUNTIME``, ``FRAMEWORK``, and ``BUNDLE``.
-Executables are treated as ``RUNTIME`` targets, except that those
-marked with the ``MACOSX_BUNDLE`` property are treated as ``BUNDLE``
+project.  There are six kinds of target files that may be installed:
+``ARCHIVE``, ``LIBRARY``, ``RUNTIME``, ``OBJECTS``, ``FRAMEWORK``, and
+``BUNDLE``. Executables are treated as ``RUNTIME`` targets, except that
+those marked with the ``MACOSX_BUNDLE`` property are treated as ``BUNDLE``
 targets on OS X.  Static libraries are treated as ``ARCHIVE`` targets,
 except that those marked with the ``FRAMEWORK`` property are treated
 as ``FRAMEWORK`` targets on OS X.
@@ -99,10 +99,11 @@ targets, except that those marked with the ``FRAMEWORK`` property are
 treated as ``FRAMEWORK`` targets on OS X.  For DLL platforms the DLL
 part of a shared library is treated as a ``RUNTIME`` target and the
 corresponding import library is treated as an ``ARCHIVE`` target.
-All Windows-based systems including Cygwin are DLL platforms.
-The ``ARCHIVE``, ``LIBRARY``, ``RUNTIME``, and ``FRAMEWORK`` arguments
-change the type of target to which the subsequent properties apply.
-If none is given the installation properties apply to all target
+All Windows-based systems including Cygwin are DLL platforms. Object
+libraries are always treated as ``OBJECTS`` targets.
+The ``ARCHIVE``, ``LIBRARY``, ``RUNTIME``, ``OBJECTS``, and ``FRAMEWORK``
+arguments change the type of target to which the subsequent properties
+apply. If none is given the installation properties apply to all target
 types.  If only one is given then only targets of that type will be
 installed (which can be used to install just a DLL or just an import
 library).
@@ -165,8 +166,8 @@ the ``mySharedLib`` DLL will be installed to ``<prefix>/bin`` and
 
 The ``EXPORT`` option associates the installed target files with an
 export called ``<export-name>``.  It must appear before any ``RUNTIME``,
-``LIBRARY``, or ``ARCHIVE`` options.  To actually install the export
-file itself, call ``install(EXPORT)``, documented below.
+``LIBRARY``, ``ARCHIVE``, or ``OBJECTS`` options.  To actually install the
+export file itself, call ``install(EXPORT)``, documented below.
 
 Installing a target with the :prop_tgt:`EXCLUDE_FROM_ALL` target property
 set to ``TRUE`` has undefined behavior.