Apply patch from hedronvision#199.

refresh.template.py

@@ -614,6 +614,10 @@ def _get_files(compile_action):
     """Gets the ({source files}, {header files}) clangd should be told the command applies to."""
 
     # Getting the source file is a little trickier than it might seem.
+    is_precompiled_header = any([arg == "-xc++-header" for arg in compile_action.arguments])
+    if is_precompiled_header:
+        header_files = [arg for arg in compile_action.arguments if not arg.startswith('-') and arg.endswith(".h")]
+        return set(), set(header_files)
 
     # First, we do the obvious thing: Filter args to those that look like source files.
     source_file_candidates = [arg for arg in compile_action.arguments if not arg.startswith('-') and arg.endswith(_get_files.source_extensions)]