Rust toolchain mismatch: building for wasm32-wasip1 instead of wasm32-wasip2

[avrabe]

Summary

The build is failing because the Rust toolchain is configured for wasm32-wasip1 but the platform transition expects wasm32-wasip2.

Error

ERROR: /private/var/tmp/_bazel_r/1ca65a983d68290a99a9611f71f46bcb/external/rules_rust++rust+rust_macos_aarch64__wasm32-wasip1__stable_tools/BUILD.bazel:97:15: Linking external/rules_rust++rust+rust_macos_aarch64__wasm32-wasip1__stable_tools/librust_toolchain.a failed: (Exit 1): true failed: error executing CppArchive command (from target @@rules_rust++rust+rust_macos_aarch64__wasm32-wasip1__stable_tools//:rust_toolchain) /bin/true rcsD bazel-out/darwin_arm64-fastbuild-ST-805526428602/bin/external/rules_rust++rust+rust_macos_aarch64__wasm32-wasip1__stable_tools/librust_toolchain.a ... (remaining 2 arguments skipped)

src/main/tools/process-wrapper-legacy.cc:80: "execvp(/bin/true, ...)": No such file or directory

Problem Analysis

1. Platform transition in rust/transitions.bzl line 6 sets: "//command_line_option:platforms": "//platforms:wasm32-wasip2"
2. Common constants in common/common.bzl line 4 defines: WASM_TARGET_TRIPLE = "wasm32-wasip2"
3. But actual build shows: wasm32-wasip1 in the error path

Expected Behavior

The Rust toolchain should be configured for wasm32-wasip2 to match the platform definitions.

Steps to Reproduce

1. Use rust_wasm_component_bindgen in a BUILD file
2. Build the target: bazel build //path/to:target
3. Build fails with wasm32-wasip1 toolchain error

Environment

• Bazel 8.3.1
• rules_wasm_component commit: f151bef
• Platform: macOS ARM64
• rules_rust: via MODULE.bazel dependencies

Potential Fix

The platform definitions in //platforms:wasm32-wasip2 may need to be updated to properly configure the Rust toolchain for wasip2 instead of wasip1.

[avrabe]

✅ RESOLVED: Complete WASI Component Model Support Implemented

This issue has been completely resolved in commit 5db67aa. The entire WebAssembly Component Model pipeline is now working with full wasm32-wasip2 support.

🎯 What Was Fixed

1. Platform transition corrected - Now properly uses wasm32-wasip2 throughout
2. Rules_rust fork integration - All toolchain issues resolved (GitHub avrabe/rules_rust Rust toolchain mismatch: building for wasm32-wasip1 instead of wasm32-wasip2 #2 & Build strategy fails with custom git repository for wit-bindgen #4)
3. WIT bindings system rebuilt - Complete dependency resolution working
4. Component detection logic - Wasip2 outputs are already components (no conversion needed)
5. Provider forwarding fixed - RustInfo providers properly passed through transitions

🚀 How to Use the Fixed System

1. Update to the working commit:

git checkout 5db67aa

2. Build WebAssembly components with wasip2:

# Build all examples (recommended to verify everything works)
bazel build //examples/... --platforms=//platforms:wasm32-wasip2

# Build specific component
bazel build //examples/basic:hello_component --platforms=//platforms:wasm32-wasip2

3. Verify component output:

# Check the generated component has correct WIT exports
wasm-tools component wit bazel-bin/examples/basic/hello_component_wasm_lib_release.wasm

⚠️ Important Changes to Consider

1. Platform Target Updated:

• Before: Build failures with wasm32-wasip1
• Now: Use --platforms=//platforms:wasm32-wasip2 for all builds
• Why: Wasip2 has native component model support (no adapters needed)

2. MODULE.bazel Dependencies:

• Now uses rules_rust fork commit df1e8ac6 (automatically handled)
• Includes proper WASI SDK integration
• All examples are CI-compatible

3. Component Output Format:

• Wasip2 builds directly output WebAssembly components
• No manual conversion needed (wasm-tools component new is skipped)
• WIT metadata is automatically embedded

📋 Verification Checklist

After updating, verify these work:

• bazel build //examples/basic:hello_component --platforms=//platforms:wasm32-wasip2
• wasm-tools validate on the output component
• wasm-tools component wit shows your exported interfaces

🎉 Result

The rules_wasm_component repository now provides production-ready WebAssembly Component Model support with:

• ✅ Full wasm32-wasip2 component model implementation
• ✅ Automatic WIT bindings generation and linking
• ✅ Complete toolchain integration (WASI SDK + Rust)
• ✅ All examples building successfully
• ✅ CI compatibility maintained

The system is now ready for production use! 🚀