fix(cmake): Fix "IMPORTED_LOCATION not set for imported target" errors

esp-idf uses imported targets as dummy targets that are never linked.
Previous CMake versions would ignore these and not error on unset
IMPORTED_LOCATION if they are never actually linked. CMake 4.2 and newer
errors during codemodel-v2 api queries when imported targets are missing
IMPORTED_LOCATION, so set a dummy location that would error when
actually linked, which fixes the error during api queries.

Closes https://github.com/espressif/esp-idf/pull/18103

tools/cmake/build.cmake

@@ -198,6 +198,8 @@ function(__build_init idf_path)
     # Create the build target, to which the ESP-IDF build properties, dependencies are attached to.
     # Must be global so as to be accessible from any subdirectory in custom projects.
     add_library(__idf_build_target STATIC IMPORTED GLOBAL)
+    # Set the IMPORTED_LOCATION property to avoid errors on IDE codemodel queries with CMake >=4.2
+    set_property(TARGET __idf_build_target PROPERTY IMPORTED_LOCATION "${CMAKE_CURRENT_BINARY_DIR}/dummy.a")
 
     # Set the Python path (which may be passed in via -DPYTHON=) and store in a build property
     set_default(PYTHON "python")

tools/cmake/component.cmake

@@ -166,6 +166,8 @@ function(__component_add component_dir prefix component_source)
     if(NOT component_target IN_LIST component_targets)
         if(NOT TARGET ${component_target})
             add_library(${component_target} STATIC IMPORTED)
+            # Set the IMPORTED_LOCATION property to avoid errors on IDE codemodel queries with CMake >=4.2
+            set_property(TARGET ${component_target} PROPERTY IMPORTED_LOCATION "${CMAKE_CURRENT_BINARY_DIR}/dummy.a")
         endif()
         idf_build_set_property(__COMPONENT_TARGETS ${component_target} APPEND)
     else()