Add --dump-context and native/string mapping

Expose a --dump-context CLI flag and implement context JSON dumping to aid template debugging. Added dump_context_json to serialize the mapped template context (files, types, functions, classes, etc.) and updated README to document the option.

Enhance TypeMapper and mapped model to better support cstring/string and native/bridge metadata: bridge_kind, native_type, string/struct free symbols, class create/destroy symbols, pre/post call setup/cleanup lines, and call-arg handling for string parameters and struct returns. Generator context now exposes uses_ffi/uses_pkgffi/uses_ui flags to templates.

IR/normalization improvements: serializer recognizes "string" type; normalizer detects std::string and maps it to kind="string", and restricts items to source paths under src/ (skipping unknown/non-src cursors).

Parser: add macOS system include discovery via xcrun/clang to provide sensible default -I args on Darwin.

Overall these changes improve template visibility, string/native interop handling, and robustness for Mac toolchains.

Author: lijy91

tools/bindgen/README.md

@@ -438,16 +438,18 @@ cd tools/bindgen/example
 PYTHONPATH=../.. python3 -m bindgen \
   --config bindgen/config.yaml \
   --dump-ir out/ir.json \
+  --dump-context out/context.json \
   --out out
 ```
 
-示例运行后将使用 `bindgen/template` 中的模板，并把 IR 与生成结果都写到 `out`。
+示例运行后将使用 `bindgen/template` 中的模板，并把 IR、模板上下文与生成结果都写到 `out`。
 
 常用参数：
 
 - `--config` 配置文件
 - `--out` 输出目录
 - `--dump-ir` 输出 IR JSON 便于调试
+- `--dump-context` 输出模板实际消费的映射后上下文 JSON，便于排查类型/符号/桥接配置
 
 ### 生成后格式化（Post Formatters）
 

tools/bindgen/cli.py

@@ -1,6 +1,7 @@
 import argparse
 from pathlib import Path
 
+from .codegen.context import dump_context_json
 from .codegen.generator import generate_bindings
 from .config import load_config
 from .ir.serializer import dump_ir_json, load_ir_json
@@ -14,6 +15,10 @@ def main(argv=None) -> int:
     parser.add_argument("--out", required=True, help="Output directory")
     parser.add_argument("--ir", help="Load IR from existing JSON file (skips parsing)")
     parser.add_argument("--dump-ir", help="Write IR JSON to path")
+    parser.add_argument(
+        "--dump-context",
+        help="Write mapped template context JSON to path",
+    )
 
     args = parser.parse_args(argv)
 
@@ -30,6 +35,8 @@ def main(argv=None) -> int:
 
     if args.dump_ir:
         dump_ir_json(module, Path(args.dump_ir))
+    if args.dump_context:
+        dump_context_json(module, cfg.mapping, Path(args.dump_context))
 
     out_dir = Path(args.out)
     out_dir.mkdir(parents=True, exist_ok=True)