Simplify the Findyaml-cpp module

This fixes compatibility with yaml-cpp 0.8, which previously failed
because of a `get_property` call with the wrong target name.
I took the liberty to add a few simplifications along the way.

Signed-off-by: Tobias Mayer <[email protected]>

share/cmake/modules/Findyaml-cpp.cmake

@@ -10,10 +10,9 @@
 #   yaml-cpp_VERSION        - Library's version
 #
 # Global targets defined by this module:
-#   yaml-cpp
+#   yaml-cpp::yaml-cpp
 #
 # For compatibility with the upstream CMake package, the following variables and targets are defined:
-#   yaml-cpp::yaml-cpp      - Alias of the yaml-cpp target
 #   YAML_CPP_LIBRARIES      - Libraries to link against yaml-cpp
 #   YAML_CPP_INCLUDE_DIR    - Include directory
 #
@@ -42,22 +41,23 @@ if(CMAKE_BUILD_TYPE MATCHES "[Dd][Ee][Bb][Uu][Gg]")
 endif()
 
 if(NOT OCIO_INSTALL_EXT_PACKAGES STREQUAL ALL)
-    set(_yaml-cpp_REQUIRED_VARS yaml-cpp_LIBRARY)
 
-    if(NOT DEFINED yaml-cpp_ROOT)
-        # Search for yaml-cpp-config.cmake
-        find_package(yaml-cpp ${yaml-cpp_FIND_VERSION} CONFIG QUIET)
-    endif()
+    # Search for yaml-cpp-config.cmake
+    find_package(yaml-cpp ${yaml-cpp_FIND_VERSION} CONFIG QUIET)
 
     if(yaml-cpp_FOUND)
-        get_target_property(yaml-cpp_LIBRARY yaml-cpp LOCATION)
+        ### Alias target for yaml-cpp < 0.8 compatibility ###
+        if(TARGET yaml-cpp AND NOT TARGET yaml-cpp::yaml-cpp)
+            add_library(yaml-cpp::yaml-cpp ALIAS yaml-cpp)
+        endif()
+
+        set(yaml-cpp_INCLUDE_DIR ${YAML_CPP_INCLUDE_DIR})
+        get_target_property(yaml-cpp_LIBRARY yaml-cpp::yaml-cpp LOCATION)
     else()
 
         # As yaml-cpp-config.cmake search fails, search an installed library
         # using yaml-cpp.pc .
 
-        list(APPEND _yaml-cpp_REQUIRED_VARS yaml-cpp_INCLUDE_DIR yaml-cpp_VERSION)
-
         # Search for yaml-cpp.pc
         find_package(PkgConfig QUIET)
         pkg_check_modules(PC_yaml-cpp QUIET "yaml-cpp>=${yaml-cpp_FIND_VERSION}")
@@ -125,44 +125,28 @@ if(NOT OCIO_INSTALL_EXT_PACKAGES STREQUAL ALL)
         set(yaml-cpp_FIND_REQUIRED FALSE)
     endif()
 
-    include(FindPackageHandleStandardArgs)
-    find_package_handle_standard_args(yaml-cpp
-        REQUIRED_VARS 
-            ${_yaml-cpp_REQUIRED_VARS}
-        VERSION_VAR
-            yaml-cpp_VERSION
-    )
-endif()
-
-###############################################################################
-### Create target
-
-if(yaml-cpp_FOUND AND NOT TARGET yaml-cpp)
-    add_library(yaml-cpp UNKNOWN IMPORTED GLOBAL)
-    set(_yaml-cpp_TARGET_CREATE TRUE)
-endif()
-
-###############################################################################
-### Configure target ###
-
-if(_yaml-cpp_TARGET_CREATE)
-    set_target_properties(yaml-cpp PROPERTIES
-        IMPORTED_LOCATION ${yaml-cpp_LIBRARY}
-        INTERFACE_INCLUDE_DIRECTORIES ${yaml-cpp_INCLUDE_DIR}
-    )
-
-    mark_as_advanced(yaml-cpp_INCLUDE_DIR yaml-cpp_LIBRARY yaml-cpp_VERSION)
-endif()
-
-###############################################################################
-### Set variables for compatibility ###
-
-if(TARGET yaml-cpp AND NOT TARGET yaml-cpp::yaml-cpp)
-    add_library(yaml-cpp::yaml-cpp ALIAS yaml-cpp)
-endif()
-
-if(yaml-cpp_INCLUDE_DIR)
     set(YAML_CPP_INCLUDE_DIR "${yaml-cpp_INCLUDE_DIR}")
+
+    # Create target
+    if(yaml-cpp_FOUND AND NOT TARGET yaml-cpp::yaml-cpp)
+        add_library(yaml-cpp::yaml-cpp UNKNOWN IMPORTED GLOBAL)
+        set_target_properties(yaml-cpp::yaml-cpp PROPERTIES
+            IMPORTED_LOCATION ${yaml-cpp_LIBRARY}
+            INTERFACE_INCLUDE_DIRECTORIES ${yaml-cpp_INCLUDE_DIR}
+        )
+    endif()
 endif()
 
 set(YAML_CPP_LIBRARIES yaml-cpp::yaml-cpp)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(yaml-cpp
+    REQUIRED_VARS
+        yaml-cpp_LIBRARY
+        yaml-cpp_INCLUDE_DIR
+        yaml-cpp_VERSION
+    VERSION_VAR
+        yaml-cpp_VERSION
+)
+
+mark_as_advanced(yaml-cpp_INCLUDE_DIR yaml-cpp_LIBRARY yaml-cpp_VERSION)