Consume sparsediff_linalg as a git submodule

.github/workflows/cmake.yml

@@ -16,6 +16,8 @@ jobs:
 
     steps:
     - uses: actions/checkout@v3
+      with:
+        submodules: recursive
 
     - name: Install BLAS (Ubuntu)
       if: runner.os == 'Linux'

.github/workflows/conda-forge.yml

@@ -24,6 +24,8 @@ jobs:
 
     steps:
       - uses: actions/checkout@v5
+        with:
+          submodules: recursive
 
       - uses: conda-incubator/setup-miniconda@v3
         with:

.github/workflows/formatting.yml

@@ -12,6 +12,8 @@ jobs:
 
     steps:
       - uses: actions/checkout@v5
+        with:
+          submodules: recursive
 
       - name: Install clang-format
         run: brew install clang-format || true
@@ -25,7 +27,7 @@ jobs:
       # the *.h branch and .c files are never checked.
       - name: Check C formatting
         run: |
-          misformatted=$(find . \( -name '*.c' -o -name '*.h' \) -print0 | xargs -0 clang-format -style=file -output-replacements-xml | grep "<replacement " || true)
+          misformatted=$(find . -path ./sparsediff_linalg -prune -o \( -name '*.c' -o -name '*.h' \) -print0 | xargs -0 clang-format -style=file -output-replacements-xml | grep "<replacement " || true)
           if [ -n "$misformatted" ]; then
             echo "ERROR: Some files are not properly formatted. Run clang-format -i."
             exit 1

.github/workflows/guard-malloc.yml

@@ -12,6 +12,8 @@ jobs:
 
     steps:
       - uses: actions/checkout@v5
+        with:
+          submodules: recursive
 
       - name: Configure
         run: cmake -B build -S . -DCMAKE_BUILD_TYPE=Debug

.github/workflows/release.yml

@@ -14,6 +14,8 @@ jobs:
         os: [ubuntu-latest, macos-latest]
     steps:
       - uses: actions/checkout@v4
+        with:
+          submodules: recursive
 
       - name: Install BLAS (Ubuntu)
         if: runner.os == 'Linux'

.github/workflows/sanitizer.yml

@@ -15,6 +15,8 @@ jobs:
 
     steps:
       - uses: actions/checkout@v5
+        with:
+          submodules: recursive
 
       - name: Install BLAS (Ubuntu)
         if: runner.os == 'Linux'

.github/workflows/valgrind.yml

@@ -7,6 +7,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
+        with:
+          submodules: recursive
 
       - name: Install dependencies
         run: |

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "sparsediff_linalg"]
+	path = sparsediff_linalg
+	url = https://github.com/SparseDifferentiation/sparsediff_linalg

CMakeLists.txt

@@ -42,6 +42,14 @@ else()
     enable_testing()
 endif()
 set(SPARSEDIFF_LINALG_WARNINGS_AS_ERRORS ${SDE_WARNINGS_AS_ERRORS})
+# The library is a git submodule (https://github.com/SparseDifferentiation/sparsediff_linalg),
+# so a plain clone leaves the directory empty.
+if(NOT EXISTS "${PROJECT_SOURCE_DIR}/sparsediff_linalg/CMakeLists.txt")
+    message(FATAL_ERROR
+        "sparsediff_linalg/ is empty: the sparsediff_linalg submodule is not checked "
+        "out. Run\n    git submodule update --init --recursive\n"
+        "or clone with --recurse-submodules.")
+endif()
 add_subdirectory(sparsediff_linalg)
 
 add_compile_definitions(DIFF_ENGINE_VERSION="${DIFF_ENGINE_VERSION}")