fix(bench): resolve SIMD benchmark compilation errors

- Add required-features = ["simd-x86-sse41"] to simd_bench in Cargo.toml
  to ensure the feature is properly enabled when running benchmarks
- Make SIMD function imports conditional in simd_bench.rs using
  #[cfg(all(target_arch = "x86_64", target_feature = "sse4.1"))]
  guards to match the function definitions

Fixes #107

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Author: kalwalt

crates/core/Cargo.toml

@@ -118,6 +118,7 @@ harness = false
 [[bench]]
 name = "simd_bench"
 harness = false
+required-features = ["simd-x86-sse41"]
 
 [[bench]]
 name = "feature_map_bench"

crates/core/benches/simd_bench.rs

@@ -35,11 +35,14 @@
  */
 
 use criterion::{black_box, criterion_group, criterion_main, Criterion};
-use webarkitlib_rs::image_proc::{
-    box_filter_h_scalar, box_filter_h_simd_x86, box_filter_v_scalar, box_filter_v_simd_x86,
-    rgba_to_gray_scalar, rgba_to_gray_simd_x86,
-};
-use webarkitlib_rs::pattern::{dot_product_scalar, dot_product_simd_x86};
+use webarkitlib_rs::image_proc::{box_filter_h_scalar, box_filter_v_scalar, rgba_to_gray_scalar};
+use webarkitlib_rs::pattern::dot_product_scalar;
+
+#[cfg(all(target_arch = "x86_64", target_feature = "sse4.1"))]
+use webarkitlib_rs::image_proc::{box_filter_h_simd_x86, box_filter_v_simd_x86, rgba_to_gray_simd_x86};
+
+#[cfg(all(target_arch = "x86_64", target_feature = "sse4.1"))]
+use webarkitlib_rs::pattern::dot_product_simd_x86;
 
 fn bench_rgba_to_gray(c: &mut Criterion) {
     let size = 640 * 480 * 4;

issues/2026-05-06-benchmark-compilation-bug.md

@@ -0,0 +1,50 @@
+## Summary
+SIMD benchmarks fail to compile due to unconditional imports of conditionally-compiled functions and missing `required-features` declaration.
+
+## Environment
+- **Product/Service**: WebARKitLib-rs
+- **Crate**: `crates/core`
+- **Component**: Benchmarks (`simd_bench`)
+
+## Reproduction Steps
+1. Run `cargo bench --features simd`
+2. Observe compilation error in `crates/core/benches/simd_bench.rs`
+
+## Expected Behavior
+Benchmarks compile and run successfully when `--features simd` is enabled, comparing scalar and SIMD implementations.
+
+## Actual Behavior
+Compilation fails with `error[E0432]: unresolved imports` for SIMD functions:
+- `box_filter_h_simd_x86`
+- `box_filter_v_simd_x86`
+- `rgba_to_gray_simd_x86`
+- `dot_product_simd_x86`
+
+## Error Details
+```
+error[E0432]: unresolved imports `webarkitlib_rs::image_proc::box_filter_h_simd_x86`, ...
+   --> crates\core\benches\simd_bench.rs:39:26
+
+note: found an item that was configured out
+   --> crates\core\src\ar\image_proc.rs:576:15
+```
+
+The functions are gated behind `#[cfg(all(feature = "simd-image", target_arch = "x86_64", target_feature = "sse4.1"))]`.
+
+## Root Cause
+1. **Missing `required-features`**: The `simd_bench` benchmark in `Cargo.toml` didn't declare `required-features = ["simd-x86-sse41"]`, so cargo wouldn't ensure the feature is enabled when building the benchmark.
+2. **Unconditional imports**: The benchmark's top-level imports tried to import SIMD functions unconditionally, but they're only compiled when the `target_feature = "sse4.1"` cfg is true.
+
+## Impact
+**Medium** - Benchmarks cannot be run with SIMD features enabled, blocking performance testing of optimized implementations.
+
+## Solution
+1. Added `required-features = ["simd-x86-sse41"]` to the `simd_bench` configuration in `Cargo.toml`
+2. Made SIMD function imports conditional using `#[cfg(all(target_arch = "x86_64", target_feature = "sse4.1"))]` guards in `simd_bench.rs`
+
+## Files Modified
+- `crates/core/Cargo.toml` — Added required-features to simd_bench
+- `crates/core/benches/simd_bench.rs` — Made SIMD imports conditional
+
+## Additional Context
+The benchmark code already had conditional compilation guards around SIMD function calls (lines 54, 73, 105), but the imports at the top were unconditional, causing the mismatch.