feat: add comprehensive clippy support for Rust WASM components

Add full clippy (Rust linter) integration to enable code quality checks
across all Rust targets in the project.

Features added:
- Global clippy configuration via .bazelrc with --config=clippy flag
- Strict linting enabled by default (warnings, all, correctness, style,
  complexity, perf)
- New rust_wasm_component_clippy() rule for targeted clippy runs
- rust_clippy_all() helper for running clippy on multiple targets
- CI integration to run clippy on all pull requests
- Convenience script at scripts/clippy.sh

Configuration:
- Enable globally: bazel build --config=clippy //...
- Run on specific target: bazel test //path:target_clippy
- Customize via .bazelrc or per-target attributes

Documentation:
- Added comprehensive clippy guide at docs/clippy.md
- Updated example BUILD files to show clippy usage

This ensures consistent code quality and catches common Rust issues
early in the development process.

Author: avrabe

.bazelrc

@@ -29,4 +29,9 @@ build:wasi --platforms=@rules_rust//rust/platform:wasm32-wasi
 # Performance
 build --jobs=auto
 build --local_resources=memory=HOST_RAM*.8
-build --local_resources=cpu=HOST_CPUS*.8
+build --local_resources=cpu=HOST_CPUS*.8
+
+# Clippy configuration - only enable with --config=clippy
+build:clippy --aspects=@rules_rust//rust:defs.bzl%rust_clippy_aspect
+build:clippy --output_groups=+clippy_checks
+build:clippy --@rules_rust//:clippy_flags=-D,warnings,-D,clippy::all,-D,clippy::correctness,-D,clippy::style,-D,clippy::complexity,-D,clippy::perf

.github/workflows/ci.yml

@@ -51,6 +51,7 @@ jobs:
           wasm32-wasip2
           wasm32-unknown-unknown
         override: true
+        components: clippy
 
     - name: Install WASM tools
       run: |
@@ -65,6 +66,9 @@ jobs:
     - name: Run Tests
       run: bazel test //... --test_output=errors
 
+    - name: Run Clippy
+      run: bazel build --config=clippy //...
+    
     - name: Build Examples
       run: |
         bazel build //examples/basic:hello_component

docs/clippy.md

@@ -0,0 +1,102 @@
+# Clippy Support
+
+This project includes built-in support for running [Clippy](https://github.com/rust-lang/rust-clippy), the Rust linter, on all Rust WASM components.
+
+## Running Clippy
+
+### On All Targets
+
+To run clippy on all Rust targets in the project:
+
+```bash
+bazel build --config=clippy //...
+```
+
+Or use the provided script:
+
+```bash
+./scripts/clippy.sh
+```
+
+### On Specific Targets
+
+To run clippy on a specific target, you can use the `rust_wasm_component_clippy` rule:
+
+```starlark
+load("@rules_wasm_component//rust:defs.bzl", "rust_wasm_component", "rust_wasm_component_clippy")
+
+rust_wasm_component(
+    name = "my_component",
+    srcs = ["src/lib.rs"],
+    # ...
+)
+
+rust_wasm_component_clippy(
+    name = "my_component_clippy",
+    target = ":my_component",
+)
+```
+
+Then run:
+
+```bash
+bazel test //path/to:my_component_clippy
+```
+
+## Configuration
+
+### Default Lints
+
+By default, clippy is configured with the following lints as errors:
+- `warnings` - All compiler warnings
+- `clippy::all` - All default clippy lints
+- `clippy::correctness` - Code that is likely incorrect or useless
+- `clippy::style` - Code that should be written in a more idiomatic way
+- `clippy::complexity` - Code that does something simple but in a complex way
+- `clippy::perf` - Code that can be written more efficiently
+
+### Custom Configuration
+
+You can customize clippy behavior by modifying `.bazelrc`:
+
+```bash
+# Add custom clippy flags
+build:clippy --@rules_rust//:clippy_flags=-D,warnings,-W,clippy::pedantic
+```
+
+### Per-Target Configuration
+
+You can also configure clippy on a per-target basis:
+
+```starlark
+rust_wasm_component_clippy(
+    name = "my_component_clippy",
+    target = ":my_component",
+    tags = ["manual"],  # Don't run with //...
+)
+```
+
+## CI Integration
+
+Clippy is automatically run in CI for all pull requests. To ensure your code passes CI:
+
+1. Run clippy locally before pushing: `bazel build --config=clippy //...`
+2. Fix any issues reported by clippy
+3. Commit your changes
+
+## Suppressing Lints
+
+If you need to suppress a specific lint:
+
+```rust
+// Suppress for entire file
+#![allow(clippy::specific_lint)]
+
+// Suppress for specific code block
+#[allow(clippy::specific_lint)]
+fn my_function() {
+    // ...
+}
+```
+
+However, please use suppressions sparingly and document why they're necessary.

examples/basic/BUILD.bazel

@@ -1,7 +1,7 @@
 """Basic example of building a WASM component"""
 
 load("@rules_wasm_component//wit:defs.bzl", "wit_library")
-load("@rules_wasm_component//rust:defs.bzl", "rust_wasm_component", "rust_wasm_component_test")
+load("@rules_wasm_component//rust:defs.bzl", "rust_wasm_component", "rust_wasm_component_test", "rust_wasm_component_clippy")
 
 package(default_visibility = ["//visibility:public"])
 
@@ -27,4 +27,10 @@ rust_wasm_component(
 rust_wasm_component_test(
     name = "hello_component_test",
     component = ":hello_component",
+)
+
+# Run clippy on the component
+rust_wasm_component_clippy(
+    name = "hello_component_clippy",
+    target = ":hello_component",
 )

rust/clippy.bzl

@@ -0,0 +1,40 @@
+"""Clippy configuration and rules for Rust WASM components"""
+
+load("@rules_rust//rust:defs.bzl", "rust_clippy")
+
+def rust_wasm_component_clippy(name, target, **kwargs):
+    """Run clippy on a rust_wasm_component target.
+    
+    Args:
+        name: Name of the clippy test target
+        target: The rust_wasm_component target to run clippy on
+        **kwargs: Additional arguments passed to rust_clippy
+    """
+    rust_clippy(
+        name = name,
+        deps = [target],
+        **kwargs
+    )
+
+def rust_clippy_all(name, targets, **kwargs):
+    """Run clippy on multiple Rust targets.
+    
+    Args:
+        name: Name of the test suite
+        targets: List of Rust targets to run clippy on
+        **kwargs: Additional arguments passed to test_suite
+    """
+    clippy_targets = []
+    for target in targets:
+        clippy_name = "{}_clippy".format(target.split(":")[-1])
+        rust_clippy(
+            name = clippy_name,
+            deps = [target],
+        )
+        clippy_targets.append(":" + clippy_name)
+    
+    native.test_suite(
+        name = name,
+        tests = clippy_targets,
+        **kwargs
+    )

rust/defs.bzl

@@ -8,7 +8,14 @@ load(
     "//rust:rust_wasm_component_test.bzl",
     _rust_wasm_component_test = "rust_wasm_component_test",
 )
+load(
+    "//rust:clippy.bzl",
+    _rust_wasm_component_clippy = "rust_wasm_component_clippy",
+    _rust_clippy_all = "rust_clippy_all",
+)
 
 # Re-export public rules
 rust_wasm_component = _rust_wasm_component
-rust_wasm_component_test = _rust_wasm_component_test
+rust_wasm_component_test = _rust_wasm_component_test
+rust_wasm_component_clippy = _rust_wasm_component_clippy
+rust_clippy_all = _rust_clippy_all

scripts/clippy.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+# Run clippy on all Rust targets in the project
+
+set -e
+
+echo "Running clippy on all Rust targets..."
+
+# Run clippy using the clippy configuration
+bazel build --config=clippy //...
+
+echo "Clippy checks completed successfully!"

test/clippy/BUILD.bazel

@@ -0,0 +1,14 @@
+"""Test clippy configuration"""
+
+load("@rules_rust//rust:defs.bzl", "rust_library", "rust_clippy")
+
+rust_library(
+    name = "test_lib",
+    srcs = ["test.rs"],
+    edition = "2021",
+)
+
+rust_clippy(
+    name = "test_lib_clippy",
+    deps = [":test_lib"],
+)

test/clippy/test.rs

@@ -0,0 +1,16 @@
+//! Test file for clippy
+
+#[allow(dead_code)]
+fn main() {
+    // This should trigger clippy warnings if not suppressed
+    let x = 1;
+    let y = 1;
+    if x == 1 && y == 1 {
+        println!("test");
+    }
+}
+
+#[allow(dead_code)]
+fn unused_function() {
+    // This would normally trigger dead_code warning
+}