Don't explode if given paths outside the root dir

Author: multiplemonomials

tools/cmake/mbed_generate_configuration.cmake

@@ -43,13 +43,15 @@ if(NOT MBED_NEED_TO_RECONFIGURE)
     file(TIMESTAMP ${CMAKE_CURRENT_BINARY_DIR}/mbed_config.cmake MBED_CONFIG_CMAKE_TIMESTAMP "%s" UTC)
 
     foreach(CONFIG_JSON ${MBED_CONFIG_JSON_SOURCE_FILES})
-        if(NOT EXISTS ${CMAKE_SOURCE_DIR}/${CONFIG_JSON})
+        get_filename_component(CONFIG_JSON_ABSPATH ${CONFIG_JSON} ABSOLUTE)
+
+        if(NOT EXISTS ${CONFIG_JSON_ABSPATH})
             message(STATUS "Mbed: ${CONFIG_JSON} deleted or renamed, regenerating configs...")
             set(MBED_NEED_TO_RECONFIGURE TRUE)
             break()
         endif()
 
-        file(TIMESTAMP ${CMAKE_SOURCE_DIR}/${CONFIG_JSON} CONFIG_JSON_TIMESTAMP "%s" UTC)
+        file(TIMESTAMP ${CONFIG_JSON_ABSPATH} CONFIG_JSON_TIMESTAMP "%s" UTC)
         if(${CONFIG_JSON_TIMESTAMP} GREATER ${MBED_CONFIG_CMAKE_TIMESTAMP})
             message(STATUS "Mbed: ${CONFIG_JSON} modified, regenerating configs...")
             set(MBED_NEED_TO_RECONFIGURE TRUE)

tools/python/mbed_tools/build/_internal/config/assemble_build_config.py

@@ -52,7 +52,14 @@ def assemble_config(target_attributes: dict, program: MbedProgram) -> Config:
         config.json_sources.append(program.files.custom_targets_json)
 
     # Make all JSON sources relative paths to the program root
-    config.json_sources = [json_source.relative_to(program.root) for json_source in config.json_sources]
+    def make_relative_if_possible(path: Path):
+        # Sadly, Pathlib did not gain a better way to do this until newer python versions.
+        try:
+            return path.relative_to(program.root)
+        except ValueError:
+            return path
+
+    config.json_sources = [make_relative_if_possible(program.root) for json_source in config.json_sources]
 
     return config
 

tools/python/mbed_tools/build/_internal/config/config.py

@@ -24,7 +24,7 @@ class Config(UserDict):
 
     # List of JSON files used to create this config.  Dumped to CMake at the end of configuration
     # so that it can regenerate configuration if the JSONs change.
-    # All paths will be relative to the Mbed program root directory.
+    # All paths will be relative to the Mbed program root directory, or absolute if outside said directory.
     json_sources: List[pathlib.Path] = []
 
     def __setitem__(self, key: Hashable, item: Any) -> None: