fix: filter __builtin_ types, install numpy in CI

Author: elijahr

.github/workflows/test.yml

@@ -91,6 +91,10 @@ jobs:
           # Install clang2 package version matching system libclang
           uv pip install --system "clang2==${LLVM_MAJOR_VERSION}.*"
 
+      - name: Install numpy for test headers (Linux)
+        if: runner.os == 'Linux'
+        run: uv pip install --system numpy
+
       - name: Test all backends (Linux)
         if: runner.os == 'Linux'
         run: pytest ./test

autopxd/backends/libclang_backend.py

@@ -1253,6 +1253,12 @@ def _process_typedef(self, cursor: "clang.cindex.Cursor") -> None:
 
         underlying = cursor.underlying_typedef_type
 
+        # Skip typedefs that reference compiler builtin types
+        # These are internal to GCC/Clang and cannot be used in Cython
+        underlying_spelling = underlying.spelling
+        if underlying_spelling.startswith("__builtin_"):
+            return
+
         # Special handling for struct/union typedefs that have inline definitions
         # e.g., typedef struct foo { int x; } foo_t;
         # We need to emit the struct definition first, then the typedef