build target

Author: vgvassilev

.github/workflows/root.yml

@@ -103,6 +103,23 @@ jobs:
           cling
         key: ${{ steps.cache.outputs.cache-primary-key }}
 
+    - name: Build clangInterpreter for ROOT's bundled cling
+      shell: bash
+      run: |
+        # Build_LLVM's cling-case ninja line builds `clang LLVMOrcDebugging
+        # clingInterpreter` -- it does not produce `libclangInterpreter.a`
+        # (upstream clang's Interpreter / clang-repl library). The cling
+        # version we cache (v1.3) doesn't depend on it, but ROOT's bundled
+        # `interpreter/cling/` is newer and links against it, so the ROOT
+        # build fails with `libclangInterpreter.a ... missing and no known
+        # rule to make it`. Build it incrementally here -- on a cache hit
+        # this is a no-op once the lib is present; on a cache miss the
+        # lib is small relative to the rest of LLVM. Build_LLVM preserves
+        # `build/build.ninja` for the cling branch and the source-tree
+        # trim keeps `clang/lib/`, so the incremental build has what it
+        # needs.
+        ninja -C "$GITHUB_WORKSPACE/llvm-project/build" clangInterpreter
+
     - name: Verify cached LLVM/Clang layout
       shell: bash
       run: |