CMake: "Flatten" metalibs more

By "flatten" I mean that component libraries aren't referenced by
genex anymore; instead, their include directories and libraries
are copied out of their interfaces and into the interface of
the metalib.

This prepares for exporting our targets, by making sure that the
component libraries don't have to be installed for CMake to be
able to export metalibs.

cmake/macros/BuildMetalib.cmake

@@ -201,7 +201,11 @@ function(add_metalib target_name)
     endif()
   endforeach()
 
-  set(defines)
+  string(REPLACE ";" "|" piped_components "${components}")
+  set(component_genex_regex ".*TARGET_PROPERTY:(${piped_components}),.*")
+
+  set(private_defines)
+  set(interface_defines)
   set(includes)
   set(libs)
   set(component_init_funcs "")
@@ -212,6 +216,7 @@ function(add_metalib target_name)
         "Missing component library ${component} referenced by metalib ${target_name}!
         (Component library targets must be created BEFORE add_metalib.)")
     endif()
+
     get_target_property(is_component "${component}" IS_COMPONENT)
     if(NOT is_component)
       message(FATAL_ERROR
@@ -231,9 +236,49 @@ function(add_metalib target_name)
     endif()
 
     if(BUILD_METALIBS)
-      list(APPEND defines "$<TARGET_PROPERTY:${component},COMPILE_DEFINITIONS>")
-      list(APPEND includes "$<TARGET_PROPERTY:${component},INTERFACE_INCLUDE_DIRECTORIES>")
-      list(APPEND libs "$<TARGET_PROPERTY:${component},INTERFACE_LINK_LIBRARIES>")
+      # This will be an object library we're pulling in; rather than link,
+      # let's try to "flatten" all of its properties into ours.
+
+      # Private defines: Just reference using a generator expression
+      list(APPEND private_defines "$<TARGET_PROPERTY:${component},COMPILE_DEFINITIONS>")
+      # Interface defines: Copy those
+      get_target_property(component_defines "${component}" INTERFACE_COMPILE_DEFINITIONS)
+      if(component_defines)
+        list(APPEND interface_defines ${component_defines})
+      endif()
+
+      # Include directories: Filter out anything that references a component
+      # library or anything in the project path
+      get_target_property(component_includes "${component}" INTERFACE_INCLUDE_DIRECTORIES)
+      foreach(component_include ${component_includes})
+        if(component_include MATCHES "${component_genex_regex}")
+          # Ignore component references
+        elseif(component_include MATCHES "^${PROJECT_SOURCE_DIR}")
+          # Include path within project; should only be included when building
+          list(APPEND includes "$<BUILD_INTERFACE:${component_include}>")
+        else()
+          # Anything else gets included
+          list(APPEND includes "${component_include}")
+        endif()
+      endforeach(component_include)
+
+      # Link libraries: Filter out component libraries; we aren't linking
+      # against them, we're using their objects
+      get_target_property(component_libraries "${component}" INTERFACE_LINK_LIBRARIES)
+      foreach(component_library ${component_libraries})
+        if(NOT component_library)
+          # NOTFOUND - guess there are no INTERFACE_LINK_LIBRARIES
+        elseif(component_library MATCHES "${component_genex_regex}")
+          # Ignore component references
+        elseif(component_library MATCHES ".*(${piped_components}).*")
+          # Component library, ignore
+        else()
+          # Anything else gets included
+          list(APPEND libs "${component_library}")
+        endif()
+      endforeach(component_library)
+
+      # Consume this component's objects
       list(APPEND sources "$<TARGET_OBJECTS:${component}>")
     else()
       list(APPEND libs "${component}")
@@ -252,8 +297,12 @@ function(add_metalib target_name)
   endif()
 
   add_library("${target_name}" ${sources})
-  target_compile_definitions("${target_name}" PRIVATE ${defines})
+  target_compile_definitions("${target_name}"
+    PRIVATE ${private_defines}
+    INTERFACE ${interface_defines})
   target_link_libraries("${target_name}" ${libs})
-  target_include_directories("${target_name}" PUBLIC ${includes})
+  target_include_directories("${target_name}"
+    PUBLIC ${includes}
+    INTERFACE "$<INSTALL_INTERFACE:$<INSTALL_PREFIX>/include/panda3d>")
 
 endfunction(add_metalib)

panda/metalibs/pandagl/CMakeLists.txt

@@ -7,7 +7,7 @@ if(HAVE_GL)
     HAVE_WGL, HAVE_COCOA, HAVE_CARBON, or HAVE_GLX must be defined.")
   endif()
 
-  set(PANDAGL_LINK_TARGETS p3glgsg)
+  set(PANDAGL_LINK_TARGETS p3glgsg p3glstuff)
 
   if(HAVE_GLX)
     list(APPEND PANDAGL_LINK_TARGETS p3glxdisplay p3x11display)