cmake : allow repeated find_package calls for llama (#29228)

cmake/llama-config.cmake.in

@@ -17,14 +17,16 @@ find_library(llama_LIBRARY llama
     NO_CMAKE_FIND_ROOT_PATH
 )
 
-add_library(llama UNKNOWN IMPORTED)
-set_target_properties(llama
-    PROPERTIES
-        INTERFACE_INCLUDE_DIRECTORIES "${LLAMA_INCLUDE_DIR}"
-        INTERFACE_LINK_LIBRARIES "ggml::ggml;ggml::ggml-base;"
-        IMPORTED_LINK_INTERFACE_LANGUAGES "CXX"
-        IMPORTED_LOCATION "${llama_LIBRARY}"
-        INTERFACE_COMPILE_FEATURES c_std_90
-        POSITION_INDEPENDENT_CODE ON)
+if(NOT TARGET llama)
+    add_library(llama UNKNOWN IMPORTED)
+    set_target_properties(llama
+        PROPERTIES
+            INTERFACE_INCLUDE_DIRECTORIES "${LLAMA_INCLUDE_DIR}"
+            INTERFACE_LINK_LIBRARIES "ggml::ggml;ggml::ggml-base;"
+            IMPORTED_LINK_INTERFACE_LANGUAGES "CXX"
+            IMPORTED_LOCATION "${llama_LIBRARY}"
+            INTERFACE_COMPILE_FEATURES c_std_90
+            POSITION_INDEPENDENT_CODE ON)
+endif()
 
 check_required_components(Llama)

examples/simple-cmake-pkg/CMakeLists.txt

@@ -5,6 +5,9 @@ set(TARGET llama-simple-cmake-pkg)
 
 find_package(Llama REQUIRED)
 
+# Check that repeated package discovery does not redefine imported targets.
+find_package(Llama REQUIRED)
+
 add_executable(${TARGET} ${CMAKE_CURRENT_LIST_DIR}/../simple/simple.cpp)
 install(TARGETS ${TARGET} RUNTIME)
 target_link_libraries(${TARGET} PRIVATE llama ggml::all ${CMAKE_THREAD_LIBS_INIT})