Don't compile unnecessary platform files (e.g. ESP8266 files on ESP32) (#9354)

esphome/loader.py

@@ -112,8 +112,17 @@ class ComponentManifest:
         This will return all cpp source files that are located in the same folder as the
         loaded .py file (does not look through subdirectories)
         """
-        ret = []
+        ret: list[FileResource] = []
 
+        # Get filter function for source files
+        filter_source_files_func = getattr(self.module, "FILTER_SOURCE_FILES", None)
+
+        # Get list of files to exclude
+        excluded_files = (
+            set(filter_source_files_func()) if filter_source_files_func else set()
+        )
+
+        # Process all resources
         for resource in (
             r.name
             for r in importlib.resources.files(self.package).iterdir()
@@ -124,6 +133,11 @@ class ComponentManifest:
             if not importlib.resources.files(self.package).joinpath(resource).is_file():
                 # Not a resource = this is a directory (yeah this is confusing)
                 continue
+
+            # Skip excluded files
+            if resource in excluded_files:
+                continue
+
             ret.append(FileResource(self.package, resource))
         return ret