Fix luprex Makefile so it emits full paths, and replace add-compile-commands.py with a better way to build compile_commands.json for luprex

build.py

@@ -287,7 +287,7 @@ def build_luprex_and_integration():
     """
     This builds our C++ code, and also UnrealEngine's C++ code.
     """
-    shell(f"{INTEGRATION}/luprex", "make all 2>&1 | sed 's|^cpp/|luprex/cpp/|; s|^ext/|luprex/ext/|'")
+    shell(INTEGRATION, "make -f luprex/Makefile all")
     shell(INTEGRATION, f"{UNREALENGINE}/Engine/Build/BatchFiles/{BUILD_BAT} -waitmutex IntegrationEditor {OS} {DEBUG} {INTEGRATION}/Integration.uproject")
 
 
@@ -295,11 +295,28 @@ def build_luprex_and_integration():
 # Make a compile_commands.json file.
 #
 
-def build_intellisense_database_for_clangd():
+def build_compile_commands_from_luprex():
     """
-    This builds compile_commands.json, which tells the intellisense system
-    based on clangd how to compile each source file.
-    This also installs a .clangd file in the UnrealEngine directory.
+    Generate compile commands for luprex by parsing make dry-run output.
+    Returns a list of compile_commands.json entries.
+    """
+    result = subprocess.run(
+        ["make", "-n", "-B", "-f", "luprex/Makefile", "all"],
+        capture_output=True, text=True, check=True, cwd=INTEGRATION
+    )
+    entries = []
+    for line in result.stdout.splitlines():
+        parts = line.split()
+        if (parts[0] == "g++") and ("-c" in parts):
+            source = os.path.abspath(os.path.join(INTEGRATION, parts[-1]))
+            entries.append({ "file": source, "command": line, "directory": INTEGRATION })
+    return entries
+
+
+def build_compile_commands_from_integration():
+    """
+    Generate compile commands for Unreal/Integration by scanning RSP files
+    generated by UnrealBuildTool. Returns a list of compile_commands.json entries.
     """
     # Find clang compiler.
     clangs = list(Path(f"{UNREALENGINE}/Engine/Extras/ThirdPartyNotUE/SDKs").rglob("*-linux-gnu/bin/clang++"))
@@ -316,14 +333,22 @@ def build_intellisense_database_for_clangd():
         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
-    # Read the luprex compile commands database.
-    ccjson = json.loads(Path(f"{INTEGRATION}/luprex/build/{OS}/compile_commands.json").read_text())
-    # Generate the new commands
-    ccdir = f"{UNREALENGINE}/Engine/Source";
+    # Generate compile commands.
+    entries = []
+    ccdir = f"{UNREALENGINE}/Engine/Source"
     for cpp in sorted(cpp_to_rsp.keys()):
         rsp = cpp_to_rsp[cpp]
         args = [clang, "@"+rsp]
-        ccjson.append({ "file" : cpp, "arguments":args, "directory":ccdir })
+        entries.append({ "file": cpp, "arguments": args, "directory": ccdir })
+    return entries
+
+
+def build_compile_commands_json():
+    """
+    Build .vscode/compile_commands.json by combining compile commands
+    from luprex and from the Unreal/Integration build.
+    """
+    ccjson = build_compile_commands_from_luprex() + build_compile_commands_from_integration()
     Path(f"{INTEGRATION}/.vscode").mkdir(exist_ok=True)
     Path(f"{INTEGRATION}/.vscode/compile_commands.json").write_text(json.dumps(ccjson, indent=2))
 
@@ -385,7 +410,7 @@ store_system_config_in_globals(CONFIG)
 os.chdir(f"{INTEGRATION}/EnginePatches")
 
 if MODE == "ccjson":
-    build_intellisense_database_for_clangd()
+    build_compile_commands_json()
 
 if MODE == "code-workspace":
     generate_integration_code_workspace()
@@ -401,7 +426,7 @@ if MODE == "all":
 
 if MODE in ["all", "c++"]:
     build_luprex_and_integration()
-    build_intellisense_database_for_clangd()
+    build_compile_commands_json()
 
 if MODE == "clean":
     build_clean()