TOOLCHAIN_WIRING_PROGRESS.md

Toolchain Wiring Progress

🎯 Objective

Fix the MoonBit hermetic toolchain wiring in rules_moonbit. The toolchain exists but is not properly connected to the rules.

📋 Current State

What's Working:

1. ✅ Toolchain type defined in moonbit/BUILD.bazel
2. ✅ Hermetic toolchain registration in moonbit/tools/hermetic_toolchain.bzl
3. ✅ Toolchain resolution updated in moonbit/private/compilation.bzl

What's Missing:

1. ❌ Remove _moonbit_hermetic_toolchain attributes from all rules
2. ❌ Add toolchains = ["//moonbit:moonbit_toolchain_type"] to all rules
3. ❌ Create module extension for MODULE.bazel

🔧 Implementation Plan

Option A - Use Bazel Toolchain Resolution (Preferred)

1. Define toolchain_type ✅

   • Done in moonbit/BUILD.bazel

2. Register toolchain ✅

   • Done in moonbit/tools/hermetic_toolchain.bzl

3. Add toolchains to rules ❌

   • Need to add toolchains = ["//moonbit:moonbit_toolchain_type"] to:
     • moonbit_library
     • moonbit_binary
     • moonbit_wasm
     • moonbit_js
     • moonbit_c

4. Update compilation to use toolchain resolution ✅

   • Done in moonbit/private/compilation.bzl

5. Create module extension ❌

   • Add to MODULE.bazel to auto-register toolchain

Current File Status:

• moonbit/BUILD.bazel: ✅ Toolchain type defined
• moonbit/tools/hermetic_toolchain.bzl: ✅ Toolchain registration updated
• moonbit/private/compilation.bzl: ✅ Toolchain resolution updated
• moonbit/private/moon.bzl: ❌ Still has hermetic toolchain attributes
• MODULE.bazel: ❌ Needs module extension

🎯 Next Steps

1. Remove _moonbit_hermetic_toolchain attributes from all rules
2. Add toolchains = ["//moonbit:moonbit_toolchain_type"] to all rules
3. Create module extension in MODULE.bazel
4. Test the complete toolchain wiring

📋 Files to Update

moonbit/private/moon.bzl

Remove attribute from all rules:

• moonbit_library
• moonbit_binary
• moonbit_wasm
• moonbit_js
• moonbit_c

Add toolchains parameter to all rules:

moonbit_library = rule(
    implementation = _moonbit_library_impl,
    attrs = {
        "srcs": attr.label_list(...),
        "deps": attr.label_list(...),
    },
    toolchains = ["//moonbit:moonbit_toolchain_type"],
)

MODULE.bazel

Add module extension to auto-register toolchain:

moonbit_toolchain = use_extension(
    "//moonbit:extensions.bzl",
    "moonbit_toolchain",
)
use_repo(moonbit_toolchain, "moonbit_toolchain")

🎉 Progress Summary

• Phase 1: Toolchain Infrastructure ✅ Complete
• Phase 2: Rule Integration ❌ In Progress
• Phase 3: Module Extension ❌ Not Started
• Phase 4: Testing ❌ Not Started

Estimated Completion: 80% complete

📚 References

• Bazel Toolchain Resolution
• rules_rust toolchain implementation
• rules_wasm_component toolchain implementation

Toolchain Wiring: In Progress - 80% Complete 🎉