ENH: Updated exporting and importing of targets to support libraries and configurations.

  - Created cmExportFileGenerator hierarchy to implement export file generation
  - Installed exports use per-config import files loaded by a central one.
  - Include soname of shared libraries in import information
  - Renamed PREFIX to NAMESPACE in INSTALL(EXPORT) and EXPORT() commands
  - Move addition of CMAKE_INSTALL_PREFIX to destinations to install generators
  - Import files compute the installation prefix relative to their location when loaded
  - Add mapping of importer configurations to importee configurations
  - Rename IMPORT targets to IMPORTED targets to distinguish from windows import libraries
  - Scope IMPORTED targets within directories to isolate them
  - Place all properties created by import files in the IMPORTED namespace
  - Document INSTALL(EXPORT) and EXPORT() commands.
  - Document IMPORTED signature of add_executable and add_library
  - Enable finding of imported targets in cmComputeLinkDepends

1 files changed, 20 insertions, 1 deletions

diff --git a/Source/cmAddLibraryCommand.h b/Source/cmAddLibraryCommand.h
index 6b0f7a4..9b95b86 100644
--- a/Source/cmAddLibraryCommand.h
+++ b/Source/cmAddLibraryCommand.h
@@ -73,7 +73,26 @@ public:
       "to STATIC.\n"
       "If EXCLUDE_FROM_ALL is given the target will not be built by default. "
       "It will be built only if the user explicitly builds the target or "
-      "another target that requires the target depends on it.";
+      "another target that requires the target depends on it."
+      "\n"
+      "The add_library command can also create IMPORTED library "
+      "targets using this signature:\n"
+      "  add_library(<name> <SHARED|STATIC|MODULE> IMPORTED)\n"
+      "An IMPORTED library target references a library file located "
+      "outside the project.  "
+      "No rules are generated to build it.  "
+      "The target name has scope in the directory in which it is created "
+      "and below.  "
+      "It may be referenced like any target built within the project.  "
+      "IMPORTED libraries are useful for convenient reference from "
+      "commands like target_link_libraries.  "
+      "Details about the imported library are specified by setting "
+      "properties whose names begin in \"IMPORTED_\".  "
+      "The most important such property is IMPORTED_LOCATION "
+      "(and its per-configuration version IMPORTED_LOCATION_<CONFIG>) "
+      "which specifies the location of the main library file on disk.  "
+      "See documentation of the IMPORTED_* properties for more information."
+      ;
     }
   
   cmTypeMacro(cmAddLibraryCommand, cmCommand);