Add CI for no-std builds. (tkaitchuck#182)

Author: schungx

.github/workflows/rust.yml

@@ -167,3 +167,16 @@ jobs:
         with:
           command: check
           args: --target wasm32-unknown-unknown --no-default-features
+  no_std:
+    name: no-std build
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - uses: actions-rs/toolchain@v1
+      with:
+        toolchain: nightly
+        override: true
+    - uses: actions-rs/cargo@v1
+      with:
+        command: build
+        args: --manifest-path=no_std_test/Cargo.toml

no_std_test/Cargo.toml

@@ -0,0 +1,34 @@
+[workspace]
+
+[package]
+name = "no_std_test"
+version = "0.1.0"
+edition = "2018"
+authors = ["Stephen Chung"]
+description = "no-std test application"
+
+[dependencies]
+ahash = { path = "../", default_features = false }
+wee_alloc = { version = "0.4.5", default_features = false }
+
+[profile.dev]
+panic = "abort"
+
+[profile.release]
+opt-level = "z"          # optimize for size
+debug = false
+rpath = false
+debug-assertions = false
+codegen-units = 1
+panic = "abort"
+
+[profile.unix]
+inherits = "release"
+lto = true
+
+[profile.windows]
+inherits = "release"
+
+[profile.macos]
+inherits = "release"
+lto = "fat"

no_std_test/src/main.rs

@@ -0,0 +1,50 @@
+//! This is a bare-bones `no-std` application that hashes a value and
+//! uses the hash value as the return value.
+
+#![no_std]
+#![feature(alloc_error_handler, start, core_intrinsics, lang_items, link_cfg)]
+
+#[global_allocator]
+static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT;
+
+use core::hash::{Hash, Hasher};
+
+// NB: Rust needs a CRT runtime on Windows MSVC.
+#[cfg(all(windows, target_env = "msvc"))]
+#[link(name = "msvcrt")]
+#[link(name = "libcmt")]
+extern "C" {}
+
+#[start]
+fn main(_argc: isize, _argv: *const *const u8) -> isize {
+	let mut h: ahash::AHasher = Default::default();
+	42_i32.hash(&mut h);
+	return h.finish() as isize;
+}
+
+
+#[alloc_error_handler]
+fn foo(_: core::alloc::Layout) -> ! {
+    core::intrinsics::abort();
+}
+
+#[panic_handler]
+#[lang = "panic_impl"]
+fn rust_begin_panic(_: &core::panic::PanicInfo) -> ! {
+    core::intrinsics::abort();
+}
+
+#[no_mangle]
+extern "C" fn _rust_eh_personality() {}
+
+#[no_mangle]
+extern "C" fn rust_eh_personality() {}
+
+#[no_mangle]
+extern "C" fn rust_eh_register_frames() {}
+
+#[no_mangle]
+extern "C" fn rust_eh_unregister_frames() {}
+
+#[no_mangle]
+extern "C" fn _Unwind_Resume() {}