[RNE Rewrite] chore: set up clangd for C++ sources

.gitignore

@@ -15,6 +15,9 @@ jsconfig.json
 .cache/
 compile_commands.json
 compile_flags.txt
+# ...but the core package ships a shared, committed clangd config for its C++ sources:
+!/packages/react-native-executorch/.clangd
+!/packages/react-native-executorch/compile_flags.txt
 
 # Xcode
 #

CONTRIBUTING.md

@@ -45,6 +45,40 @@ Found a model you would like to use in your app but it is not currently supplied
 Do you have a neat example use case and want to share it with us? You can just drop us a message on Discord server and/or open a PR to `apps` directory here.
 If you found some inconsistencies in our documentation or just something is missing just open a PR with suggested changes (remember to add changes to previous docs versions too, e.g `docs/versioned_docs/version-0.3.x`, `docs/versioned_docs/version-0.4.x`).
 
+# C++ tooling (clangd)
+
+The core package ships a committed [clangd](https://clangd.llvm.org/) setup so the
+C/C++ sources under `packages/react-native-executorch/cpp` get code intelligence and
+a strict, shared set of compiler warnings:
+
+- `packages/react-native-executorch/compile_flags.txt` — the compilation database:
+  language standard, preprocessor defines, and include roots (paths are relative to
+  the package, so the config is portable). ExecuTorch/torch/JSI headers are added as
+  system includes so their internal warnings don't pollute diagnostics for our code.
+- `packages/react-native-executorch/.clangd` — the warning policy layered on top.
+
+For clangd to resolve the `<executorch/...>` and `<jsi/jsi.h>` includes you need the
+same prerequisites as a native build:
+
+1. `yarn install` at the repo root (provides the JSI headers under `node_modules`).
+2. ExecuTorch headers provisioned under `packages/react-native-executorch/third-party/include`
+   (see [third-party/README.md](./packages/react-native-executorch/third-party/README.md)).
+
+Without them clangd still lints your own code; the third-party includes simply stay
+unresolved until the headers are present.
+
+A `pre-commit` hook (lefthook) compiles staged `cpp/` sources with this same warning set
+and aborts the commit if any warning is introduced — the editor and the commit gate stay
+in sync. It skips automatically when no compiler or the provisioned headers are available,
+so it never blocks contributors who don't build the native code; bypass with
+`git commit --no-verify`.
+
+Editor setup: install the official **clangd** extension (e.g. `llvm-vs-code-extensions.vscode-clangd`
+for VS Code) and disable the default Microsoft C/C++ IntelliSense engine so the two
+don't conflict. clangd discovers `compile_flags.txt`/`.clangd` automatically from the
+open file's directory. If you produce a `compile_commands.json` from a native build,
+clangd will prefer it — it's gitignored and takes precedence over `compile_flags.txt`.
+
 # Creating a Pull Request
 
 Before writing any code reach out to us to make sure no one is currently working on it, you can always open an issue first.

lefthook.yml

@@ -13,6 +13,9 @@ pre-commit:
     format-objc:
       glob: '*.{h,hpp,m,mm,c,cpp}'
       run: clang-format -i {staged_files} && git add {staged_files}
+    cpp-warnings:
+      glob: '*.{h,hpp,c,cpp}'
+      run: packages/react-native-executorch/scripts/check-cpp-warnings.sh {staged_files}
     format-kotlin:
       glob: '*.{kt}'
       run: ktlint -F {staged_files} && git add {staged_files}

packages/react-native-executorch/.clangd

@@ -0,0 +1,33 @@
+# clangd configuration for the react-native-executorch C/C++ sources.
+#
+# Include roots, the language standard, and preprocessor defines live in
+# `compile_flags.txt` (the compilation database). This file layers the project's
+# warning policy on top and configures clangd's diagnostics.
+#
+# The warning set is intentionally strict to surface bugs early during the
+# rewrite. Third-party headers are included as `-isystem` (see compile_flags.txt),
+# so these warnings only apply to our own code in `cpp/`.
+CompileFlags:
+  Add:
+    - -Wall
+    - -Wextra
+    - -Wpedantic
+    - -Wshadow
+    - -Wnon-virtual-dtor
+    - -Woverloaded-virtual
+    - -Wold-style-cast
+    - -Wcast-align
+    - -Wunused
+    - -Wnull-dereference
+    - -Wimplicit-fallthrough
+    - -Wextra-semi
+    - -Wformat=2
+    - -Wconversion
+    - -Wsign-conversion
+    - -Wdouble-promotion
+
+Diagnostics:
+  # ExecuTorch/torch rely heavily on umbrella headers, which clangd's include
+  # cleaner misreports as unused/missing. Disable it to avoid false positives.
+  UnusedIncludes: None
+  MissingIncludes: None

packages/react-native-executorch/compile_flags.txt

@@ -0,0 +1,11 @@
+-xc++
+-std=c++20
+-DC10_USING_CUSTOM_GENERATED_MACROS=1
+-DEXECUTORCH_ENABLE_EXECUTION_PROFILING=1
+-Icpp
+-isystem../../node_modules/react-native/ReactCommon/jsi
+-isystemthird-party/include
+-isystemthird-party/include/executorch/extension/llm/tokenizers/include
+-isystemthird-party/include/executorch/extension/llm/tokenizers/third-party/json/include
+-isystemthird-party/include/executorch/extension/llm/tokenizers/third-party/re2
+-isystemthird-party/include/executorch/extension/llm/tokenizers/third-party/abseil-cpp

packages/react-native-executorch/cpp/core/model.cpp

@@ -27,7 +27,7 @@ jsi::Value ModelHostObject::get(jsi::Runtime &rt, const jsi::PropNameID &name) {
 
     if (nameStr == "getMethodNames") {
         auto self = shared_from_this();
-        auto fnBody = [self](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+        auto fnBody = [self](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value * /*args*/, size_t count) -> jsi::Value {
             if (count != 0) {
                 throw jsi::JSError(rt, "getMethodNames: Usage: getMethodNames()");
             }
@@ -61,7 +61,7 @@ jsi::Value ModelHostObject::get(jsi::Runtime &rt, const jsi::PropNameID &name) {
 
     if (nameStr == "getMethodMeta") {
         auto self = shared_from_this();
-        auto fnBody = [self](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+        auto fnBody = [self](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value *args, size_t count) -> jsi::Value {
             if (count != 1) {
                 throw jsi::JSError(rt, "getMethodMeta: Usage: getMethodMeta(methodName)");
             }
@@ -176,7 +176,7 @@ jsi::Value ModelHostObject::get(jsi::Runtime &rt, const jsi::PropNameID &name) {
 
     if (nameStr == "execute") {
         auto self = shared_from_this();
-        auto fnBody = [self](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+        auto fnBody = [self](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value *args, size_t count) -> jsi::Value {
             if (count != 3) {
                 throw jsi::JSError(rt, "execute: Usage: execute(methodName, inputs, outputTensors)");
             }
@@ -435,7 +435,7 @@ jsi::Value ModelHostObject::get(jsi::Runtime &rt, const jsi::PropNameID &name) {
 
     if (nameStr == "dispose") {
         auto self = shared_from_this();
-        auto fnBody = [self](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+        auto fnBody = [self](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value * /*args*/, size_t count) -> jsi::Value {
             if (count != 0) {
                 throw jsi::JSError(rt, "dispose: Usage: dispose()");
             }
@@ -468,7 +468,7 @@ std::vector<facebook::jsi::PropNameID> ModelHostObject::getPropertyNames(jsi::Ru
 
 void install_loadModel(jsi::Runtime &rt, jsi::Object &module) {
     auto name = "loadModel";
-    auto fnBody = [](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+    auto fnBody = [](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value *args, size_t count) -> jsi::Value {
         if (count != 1) {
             throw jsi::JSError(rt, "loadModel: Usage: loadModel(arg0)");
         }

packages/react-native-executorch/cpp/core/tensor.cpp

@@ -38,7 +38,7 @@ jsi::Value TensorHostObject::get(jsi::Runtime &rt, const jsi::PropNameID &name)
 
     if (nameStr == "copyTo") {
         auto self = shared_from_this();
-        auto fnBody = [self](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+        auto fnBody = [self](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value *args, size_t count) -> jsi::Value {
             if (count != 1) {
                 throw jsi::JSError(rt, "copyTo: Usage: copyTo(dst)");
             }
@@ -143,7 +143,7 @@ jsi::Value TensorHostObject::get(jsi::Runtime &rt, const jsi::PropNameID &name)
 
     if (nameStr == "getData") {
         auto self = shared_from_this();
-        auto fnBody = [self](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+        auto fnBody = [self](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value *args, size_t count) -> jsi::Value {
             if (count != 1) {
                 throw jsi::JSError(rt, "getData: Usage: getData(array)");
             }
@@ -259,7 +259,7 @@ jsi::Value TensorHostObject::get(jsi::Runtime &rt, const jsi::PropNameID &name)
 
     if (nameStr == "dispose") {
         auto self = shared_from_this();
-        auto fnBody = [self](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+        auto fnBody = [self](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value * /*args*/, size_t count) -> jsi::Value {
             if (count != 0) {
                 throw jsi::JSError(rt, "dispose: Usage: dispose()");
             }
@@ -297,7 +297,7 @@ std::vector<facebook::jsi::PropNameID> TensorHostObject::getPropertyNames(jsi::R
 
 void install_createTensor(jsi::Runtime &rt, jsi::Object &module) {
     auto name = "createTensor";
-    auto fnBody = [](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+    auto fnBody = [](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value *args, size_t count) -> jsi::Value {
         if (count != 2) {
             throw jsi::JSError(rt, "createTensor: Usage: createTensor(shape, dtype)");
         }

packages/react-native-executorch/cpp/core/utils.cpp

@@ -10,7 +10,7 @@ namespace jsi = facebook::jsi;
 
 void install_getExecuTorchRegisteredBackends(jsi::Runtime &rt, jsi::Object &module) {
     auto name = "getExecuTorchRegisteredBackends";
-    auto fnBody = [](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+    auto fnBody = [](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value * /*args*/, size_t count) -> jsi::Value {
         if (count != 0) {
             throw jsi::JSError(rt, "Usage: getExecuTorchRegisteredBackends()");
         }

packages/react-native-executorch/cpp/extensions/cv/box_ops.cpp

@@ -67,7 +67,7 @@ std::array<float, 4> decodeToXyxy(
 
 void install_nms(jsi::Runtime &rt, jsi::Object &module) {
     auto name = "nms";
-    auto fnBody = [](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+    auto fnBody = [](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value *args, size_t count) -> jsi::Value {
         if (count < 3) {
             throw jsi::JSError(rt, "Usage: nms(boxes, scores, options)");
         }
@@ -143,7 +143,7 @@ void install_nms(jsi::Runtime &rt, jsi::Object &module) {
         const float *scoresPtr = reinterpret_cast<const float *>(scores->data_.get());
 
         std::vector<std::pair<std::int32_t, float>> candidates;
-        candidates.reserve(numAnchors);
+        candidates.reserve(static_cast<size_t>(numAnchors));
 
         for (size_t idx = 0; std::cmp_less(idx, numAnchors); ++idx) {
             float score = scoresPtr[idx];

packages/react-native-executorch/cpp/extensions/cv/image_ops.cpp

@@ -65,7 +65,7 @@ FitBox computeFit(int32_t srcW, int32_t srcH, int32_t dstW, int32_t dstH, bool i
 
 void install_resize(jsi::Runtime &rt, jsi::Object &module) {
     auto name = "resize";
-    auto fnBody = [](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+    auto fnBody = [](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value *args, size_t count) -> jsi::Value {
         if (count != 3) {
             throw jsi::JSError(rt, "Usage: resize(src, dst, options)");
         }
@@ -233,7 +233,7 @@ int codeToColorConversionFlag(const std::string &code) {
 
 void install_cvtColor(jsi::Runtime &rt, jsi::Object &module) {
     auto name = "cvtColor";
-    auto fnBody = [](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+    auto fnBody = [](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value *args, size_t count) -> jsi::Value {
         if (count != 3) {
             throw jsi::JSError(rt, "Usage: cvtColor(src, dst, code)");
         }
@@ -319,7 +319,7 @@ void install_cvtColor(jsi::Runtime &rt, jsi::Object &module) {
 
 void install_toChannelsFirst(jsi::Runtime &rt, jsi::Object &module) {
     auto name = "toChannelsFirst";
-    auto fnBody = [](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+    auto fnBody = [](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value *args, size_t count) -> jsi::Value {
         if (count != 2) {
             throw jsi::JSError(rt, "Usage: toChannelsFirst(src, dst)");
         }
@@ -391,7 +391,7 @@ void install_toChannelsFirst(jsi::Runtime &rt, jsi::Object &module) {
         std::vector<::cv::Mat> channels;
         ::cv::split(srcMat, channels);
 
-        int32_t hw = srcH * srcW;
+        size_t hw = static_cast<size_t>(srcH) * static_cast<size_t>(srcW);
         size_t elemSize = rnexecutorch::core::types::elementSize(src->dtype_);
         uint8_t *dstPtr = dst->data_.get();
 
@@ -407,7 +407,7 @@ void install_toChannelsFirst(jsi::Runtime &rt, jsi::Object &module) {
 
 void install_toChannelsLast(jsi::Runtime &rt, jsi::Object &module) {
     auto name = "toChannelsLast";
-    auto fnBody = [](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+    auto fnBody = [](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value *args, size_t count) -> jsi::Value {
         if (count != 2) {
             throw jsi::JSError(rt, "Usage: toChannelsLast(src, dst)");
         }
@@ -475,7 +475,7 @@ void install_toChannelsLast(jsi::Runtime &rt, jsi::Object &module) {
             throw jsi::JSError(rt, "toChannelsLast: " + std::string(e.what()));
         }
 
-        int32_t hw = srcH * srcW;
+        size_t hw = static_cast<size_t>(srcH) * static_cast<size_t>(srcW);
         size_t elemSize = rnexecutorch::core::types::elementSize(src->dtype_);
         uint8_t *srcPtr = src->data_.get();
 
@@ -495,7 +495,7 @@ void install_toChannelsLast(jsi::Runtime &rt, jsi::Object &module) {
 
 void install_normalize(jsi::Runtime &rt, jsi::Object &module) {
     auto name = "normalize";
-    auto fnBody = [](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+    auto fnBody = [](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value *args, size_t count) -> jsi::Value {
         if (count != 3) {
             throw jsi::JSError(rt, "Usage: normalize(src, dst, options)");
         }
@@ -541,7 +541,7 @@ void install_normalize(jsi::Runtime &rt, jsi::Object &module) {
             }
 
             auto val = opts.getProperty(rt, name);
-            std::vector<double> result(c);
+            std::vector<double> result(static_cast<size_t>(c));
 
             if (val.isNumber()) {
                 std::ranges::fill(result, val.asNumber());
@@ -602,9 +602,10 @@ void install_normalize(jsi::Runtime &rt, jsi::Object &module) {
         uint8_t *srcPtr = src->data_.get();
         uint8_t *dstPtr = dst->data_.get();
 
+        const size_t plane = static_cast<size_t>(h) * static_cast<size_t>(w);
         for (size_t ch = 0; std::cmp_less(ch, c); ++ch) {
-            ::cv::Mat srcChannel(h, w, srcDepthType, srcPtr + ch * h * w * srcElemSize);
-            ::cv::Mat dstChannel(h, w, dstDepthType, dstPtr + ch * h * w * dstElemSize);
+            ::cv::Mat srcChannel(h, w, srcDepthType, srcPtr + ch * plane * srcElemSize);
+            ::cv::Mat dstChannel(h, w, dstDepthType, dstPtr + ch * plane * dstElemSize);
 
             srcChannel.convertTo(dstChannel, dstDepthType, alpha[ch], beta[ch]);
         }
@@ -617,7 +618,7 @@ void install_normalize(jsi::Runtime &rt, jsi::Object &module) {
 
 void install_applyColormap(jsi::Runtime &rt, jsi::Object &module) {
     auto name = "applyColormap";
-    auto fnBody = [](jsi::Runtime &rt, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
+    auto fnBody = [](jsi::Runtime &rt, const jsi::Value & /*thisVal*/, const jsi::Value *args, size_t count) -> jsi::Value {
         if (count != 3) {
             throw jsi::JSError(rt, "Usage: applyColormap(src, dst, colormap)");
         }
@@ -695,7 +696,7 @@ void install_applyColormap(jsi::Runtime &rt, jsi::Object &module) {
                                            std::to_string(numColors) + ")");
             }
             for (size_t c = 0; c < numRgbaChannels; ++c) {
-                dstData[i * numRgbaChannels + c] = lut[idx][c];
+                dstData[i * numRgbaChannels + c] = lut[static_cast<size_t>(idx)][c];
             }
         }