More MCP work

build.py

@@ -323,6 +323,7 @@ def build_compile_commands_from_integration():
     if len(clangs) != 1: sys.exit("Couldn't identify correct clang++ compiler in UnrealEngine thirdparty directory")
     clang = str(clangs[0])
     # Build the table of source files and RSP files.
+    # First, scan unity Module.*.o.rsp files and expand their #included .cpp files.
     mods1 = Path(f"{INTEGRATION}/Intermediate/Build/{OS}").rglob(f"UnrealEditor/{DEBUG}/**/Module.*.o.rsp")
     mods1p = Path(f"{INTEGRATION}/Plugins").rglob(f"Intermediate/Build/{OS}/x64/UnrealEditor/{DEBUG}/**/Module.*.o.rsp")
     mods2 = Path(f"{UNREALENGINE}/Engine/Intermediate/Build/{OS}").rglob("UnrealEditor/Development/**/Module.*.o.rsp")
@@ -334,6 +335,15 @@ def build_compile_commands_from_integration():
         for subfile in cpp_files_included_by(cpp):
             abs = os.path.abspath(os.path.join(f"{UNREALENGINE}/Engine/Source", subfile))
             cpp_to_rsp[abs] = rsp
+    # Also pick up non-unity .cpp files that have their own .o.rsp (e.g. files
+    # excluded from unity builds). Only include if the .cpp file actually exists.
+    standalone1 = Path(f"{INTEGRATION}/Intermediate/Build/{OS}").rglob(f"UnrealEditor/{DEBUG}/**/*.cpp.o.rsp")
+    standalone1p = Path(f"{INTEGRATION}/Plugins").rglob(f"Intermediate/Build/{OS}/x64/UnrealEditor/{DEBUG}/**/*.cpp.o.rsp")
+    for rsp_path in itertools.chain(standalone1, standalone1p):
+        rsp = str(rsp_path)
+        cpp = os.path.abspath(rsp.removesuffix(".o.rsp"))
+        if cpp not in cpp_to_rsp and os.path.exists(cpp):
+            cpp_to_rsp[cpp] = rsp
     # Generate compile commands.
     entries = []
     ccdir = f"{UNREALENGINE}/Engine/Source"