Check at build-time if aes feature is enabled (and panic otherwise)

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "gxhash"
 authors = ["Olivier Giniaux"]
-version = "3.1.0"
+version = "3.1.1"
 edition = "2021"
 description = "GxHash non-cryptographic algorithm"
 license = "MIT"

README.md

@@ -36,6 +36,9 @@ Check out the [paper](https://github.com/ogxd/gxhash-rust/blob/main/article/arti
 
 ## Portability
 
+> **Important**
+> Because GxHash relies on `aes` hardware acceleration, you must make sure the `aes` feature is enabled when building (otherwise it won't build). This can be done by setting the `RUSTFLAGS` environment variable to `-C target-feature=+aes` or `-C target-cpu=native` (the latter should work if your CPU is properly recognized by rustc, which is the case most of the time).
+
 ### Architecture Compatibility
 GxHash is compatible with:
 - X86 processors with `AES-NI` & `SSE2` intrinsics

build.rs

@@ -2,10 +2,18 @@ extern crate rustc_version;
 use rustc_version::{version_meta, Channel};
 
 fn main() {
+    // When conditions permits, enable hybrid feature to leverage wider intrinsics for even more throughput
     if version_meta().unwrap().channel == Channel::Nightly
     && cfg!(target_arch = "x86_64")
     && cfg!(target_feature = "avx2")
     && cfg!(target_feature = "vaes") {
         println!("cargo:rustc-cfg=hybrid");
     }
+
+    // If not cross compiling, make sure the aes feature is available
+    if std::env::var("HOST").unwrap_or_default() == std::env::var("TARGET").unwrap_or_default()
+    && cfg!(not(target_feature = "aes")) {
+        panic!("| GxHash requires target-feature 'aes' to be enabled.\n\
+        | Build with RUSTFLAGS=\"-C target-cpu=native\" or RUSTFLAGS=\"-C target-feature=+aes\" to enable.");
+    }
 }