ci(codeql): manual c-cpp build replaces autobuild

.github/workflows/codeql.yml

@@ -74,6 +74,13 @@ jobs:
 
       - name: Install C++ build deps
         if: matrix.language == 'c-cpp'
+        # bison + flex are needed to regenerate xml.cc / slghparse.cc /
+        # slghscan.cc from their .y / .l sources during the manual
+        # build below. binutils-dev + libiberty-dev provide bfd.h —
+        # we don't *link* against libbfd (libdecomp_dbg.a is a static
+        # archive, no link step), but `analyzesigs.cc` and
+        # `loadimage_bfd.cc` `#include <bfd.h>` and therefore need
+        # the header at compile time.
         run: |
           sudo apt-get update
           sudo apt-get install -y bison flex g++ make binutils-dev libiberty-dev
@@ -97,8 +104,23 @@ jobs:
         # irrelevant to static analysis.
         run: gradle prepDev --parallel
 
-      - name: Autobuild (non-Java)
-        if: matrix.language != 'java-kotlin'
+      - name: Manual C++ build
+        if: matrix.language == 'c-cpp'
+        # Autobuild fails for this repo because the decompiler's
+        # Makefile lives at Ghidra/Features/Decompiler/src/decompile/cpp/
+        # rather than at the repo root, so `cpp/autobuilder.sh` reports
+        # "No supported build system detected" and exits 1. Build the
+        # static library `libdecomp_dbg.a` instead — that target
+        # compiles every C++ source file in the decompiler core (all
+        # LIBDECOMP_NAMES → com_dbg/*.o, then ar qc into the archive)
+        # without needing BFD at link time. CodeQL's tracer picks up
+        # the .o compile commands, which is what static analysis needs.
+        run: |
+          cd Ghidra/Features/Decompiler/src/decompile/cpp
+          make libdecomp_dbg.a
+
+      - name: Autobuild (other languages)
+        if: matrix.language != 'java-kotlin' && matrix.language != 'c-cpp'
         uses: github/codeql-action/autobuild@v3
 
       - name: Perform CodeQL Analysis