Initial commit

skills/cpython-build/SKILL.md

@@ -0,0 +1,52 @@
+---
+name: cpython-build
+description: Use this skill when you need to configure, build, or rebuild CPython from source. It covers initial setup with configure, incremental builds, platform-specific considerations, and working with Argument Clinic generated code.
+---
+
+# Building CPython
+
+**ONLY build in a `build/` subdirectory** at repo root. Never build in the source tree.
+
+## Setup and Configuration
+
+**IMPORTANT**: Use sub-agents when running configure and make build steps!
+
+```bash
+# Build directory setup
+REPO_ROOT=<path-to-cpython-git-repo>
+BUILD_DIR=$REPO_ROOT/build
+
+# Configure with debug support (enables debug symbols, assertions, runtime checks)
+cd $BUILD_DIR && ../configure --with-pydebug
+
+# Build using all CPU cores (initial or incremental)
+make -C $BUILD_DIR -j $(nproc)
+```
+
+**Platform notes**:
+- Linux: `BUILT_PY=$BUILD_DIR/python`
+- macOS: `BUILT_PY=$BUILD_DIR/python.exe` (note .exe extension)
+- Windows: Ask user how to build (uses Visual Studio, different process)
+
+## Argument Clinic
+
+After editing `.c` files that change function signatures, docstrings, or argument specs:
+```bash
+make -C $BUILD_DIR clinic
+```
+
+**NEVER** edit files in `**/clinic/**` subdirectories - they're auto-generated.
+
+## Verify Build
+
+```bash
+$BUILT_PY --version
+$BUILT_PY -c "print('Hello from CPython!')"
+```
+
+## Troubleshooting
+
+- **Missing dependencies**: Configure reports missing libraries
+- **Stale build**: `make clean` in BUILD_DIR and rebuild
+- **Clinic files out of sync**: `make -C $BUILD_DIR clinic`
+- **Clean build**: `rm -rf $BUILD_DIR && mkdir $BUILD_DIR && cd $BUILD_DIR && ../configure --with-pydebug && make -C $BUILD_DIR -j $(nproc)`