Use stable Rust on CI to test the x64 backend (#2766)

* Use stable Rust on CI to test the x64 backend

This commit leverages the newly-released 1.51.0 compiler to test the
new backend on Windows and Linux with a stable compiler instead of a
nightly compiler. This isolates the nightly build to just the nightly
documentation generation and fuzzing, both of which rely on nightly for
the best results right now.

* Use updated stable in book build job

* Run rustfmt for new stable

* Silence new warnings for wasi-nn

* Allow some dead code in the x64 backend

Looks like new rustc is better about emitting some dead-code warnings

* Update rust in peepmatic job

* Fix a test in the pooling allocator

* Remove `package.metdata.docs.rs` temporarily

Needs resolution of https://github.com/rust-lang/cargo/pull/9300 first

* Fix a warning in a wasi-nn example

crates/jit/src/unwind/systemv.rs

@@ -90,7 +90,10 @@ impl UnwindRegistry {
         let mut eh_frame = EhFrame(EndianVec::new(RunTimeEndian::default()));
         table.write_eh_frame(&mut eh_frame).unwrap();
 
-        if cfg!(any(all(target_os = "linux", target_env = "gnu"), target_os = "freebsd")) {
+        if cfg!(any(
+            all(target_os = "linux", target_env = "gnu"),
+            target_os = "freebsd"
+        )) {
             // libgcc expects a terminating "empty" length, so write a 0 length at the end of the table.
             eh_frame.0.write_u32(0).unwrap();
         }
@@ -101,7 +104,10 @@ impl UnwindRegistry {
     }
 
     unsafe fn register_frames(&mut self) {
-        if cfg!(any(all(target_os = "linux", target_env = "gnu"), target_os = "freebsd")) {
+        if cfg!(any(
+            all(target_os = "linux", target_env = "gnu"),
+            target_os = "freebsd"
+        )) {
             // On gnu (libgcc), `__register_frame` will walk the FDEs until an entry of length 0
             let ptr = self.frame_table.as_ptr();
             __register_frame(ptr);

crates/runtime/src/instance/allocator/pooling.rs

@@ -1618,7 +1618,7 @@ mod test {
     }
 
     #[cfg_attr(target_arch = "aarch64", ignore)] // https://github.com/bytecodealliance/wasmtime/pull/2518#issuecomment-747280133
-    #[cfg(all(unix, target_pointer_width = "64"))]
+    #[cfg(all(unix, target_pointer_width = "64", feature = "async"))]
     #[test]
     fn test_stack_zeroed() -> Result<()> {
         let allocator = PoolingInstanceAllocator::new(

crates/wasi-nn/examples/classification-example/src/main.rs

@@ -49,7 +49,8 @@ pub fn main() {
             0,
             &mut output_buffer[..] as *mut [f32] as *mut u8,
             (output_buffer.len() * 4).try_into().unwrap(),
-        );
+        )
+        .unwrap();
     }
     println!(
         "Found results, sorted top 5: {:?}",

crates/wasi-nn/examples/wasi-nn-rust-bindings/src/generated.rs

@@ -152,6 +152,7 @@ pub unsafe fn compute(context: GraphExecutionContext) -> Result<()> {
     }
 }
 
+#[allow(improper_ctypes)]
 pub mod wasi_ephemeral_nn {
     use super::*;
     #[link(wasm_import_module = "wasi_ephemeral_nn")]

crates/wasmtime/Cargo.toml

@@ -9,8 +9,9 @@ repository = "https://github.com/bytecodealliance/wasmtime"
 readme = "README.md"
 edition = "2018"
 
-[package.metadata.docs.rs]
-rustdoc-args = ["--cfg", "nightlydoc"]
+# FIXME(rust-lang/cargo#9300): uncomment once that lands
+# [package.metadata.docs.rs]
+# rustdoc-args = ["--cfg", "nightlydoc"]
 
 [dependencies]
 wasmtime-runtime = { path = "../runtime", version = "0.25.0" }