Fix some nightly dead code warnings (#3404)

* Fix some nightly dead code warnings

Looks like the "struct field not used" lint has improved on nightly and
caught a few more instances of fields that were never actually read.

* Fix windows

cranelift/codegen/meta/src/cdsl/instructions.rs

@@ -35,7 +35,6 @@ impl<'all_inst> InstructionGroupBuilder<'all_inst> {
 pub(crate) struct PolymorphicInfo {
     pub use_typevar_operand: bool,
     pub ctrl_typevar: TypeVar,
-    pub other_typevars: Vec<TypeVar>,
 }
 
 #[derive(Debug)]
@@ -52,8 +51,6 @@ pub(crate) struct InstructionContent {
     pub operands_in: Vec<Operand>,
     /// Output operands. The output operands must be SSA values or `variable_args`.
     pub operands_out: Vec<Operand>,
-    /// Instruction-specific TypeConstraints.
-    pub constraints: Vec<Constraint>,
 
     /// Instruction format, automatically derived from the input operands.
     pub format: Rc<InstructionFormat>,
@@ -296,7 +293,6 @@ impl InstructionBuilder {
             doc: self.doc,
             operands_in,
             operands_out,
-            constraints: self.constraints.unwrap_or_else(Vec::new),
             format: self.format,
             polymorphic_info,
             value_opnums,
@@ -404,11 +400,10 @@ fn verify_polymorphic(
                 || tv.singleton_type().is_some()
             {
                 match is_ctrl_typevar_candidate(tv, &operands_in, &operands_out) {
-                    Ok(other_typevars) => {
+                    Ok(_other_typevars) => {
                         return Some(PolymorphicInfo {
                             use_typevar_operand: true,
                             ctrl_typevar: tv.clone(),
-                            other_typevars,
                         });
                     }
                     Err(error_message) => {
@@ -439,12 +434,11 @@ fn verify_polymorphic(
 
     // At this point, if the next unwrap() fails, it means the output type couldn't be used as a
     // controlling type variable either; panicking is the right behavior.
-    let other_typevars = is_ctrl_typevar_candidate(tv, &operands_in, &operands_out).unwrap();
+    is_ctrl_typevar_candidate(tv, &operands_in, &operands_out).unwrap();
 
     Some(PolymorphicInfo {
         use_typevar_operand: false,
         ctrl_typevar: tv.clone(),
-        other_typevars,
     })
 }
 

crates/runtime/src/instance/allocator.rs

@@ -577,6 +577,7 @@ unsafe fn initialize_vmcontext_globals(instance: &Instance) {
 #[derive(Clone)]
 pub struct OnDemandInstanceAllocator {
     mem_creator: Option<Arc<dyn RuntimeMemoryCreator>>,
+    #[cfg(feature = "async")]
     stack_size: usize,
 }
 
@@ -594,8 +595,10 @@ fn borrow_limiter<'a>(
 impl OnDemandInstanceAllocator {
     /// Creates a new on-demand instance allocator.
     pub fn new(mem_creator: Option<Arc<dyn RuntimeMemoryCreator>>, stack_size: usize) -> Self {
+        drop(stack_size); // suppress unused warnings w/o async feature
         Self {
             mem_creator,
+            #[cfg(feature = "async")]
             stack_size,
         }
     }
@@ -642,6 +645,7 @@ impl Default for OnDemandInstanceAllocator {
     fn default() -> Self {
         Self {
             mem_creator: None,
+            #[cfg(feature = "async")]
             stack_size: 0,
         }
     }

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

@@ -907,11 +907,11 @@ impl StackPool {
 pub struct PoolingInstanceAllocator {
     strategy: PoolingAllocationStrategy,
     module_limits: ModuleLimits,
-    instance_limits: InstanceLimits,
     // This is manually drop so that the pools unmap their memory before the page fault handler drops.
     instances: mem::ManuallyDrop<InstancePool>,
     #[cfg(all(feature = "async", unix))]
     stacks: StackPool,
+    #[cfg(all(feature = "async", windows))]
     stack_size: usize,
     #[cfg(all(feature = "uffd", target_os = "linux"))]
     _fault_handler: imp::PageFaultHandler,
@@ -935,13 +935,15 @@ impl PoolingInstanceAllocator {
         #[cfg(all(feature = "uffd", target_os = "linux"))]
         let _fault_handler = imp::PageFaultHandler::new(&instances)?;
 
+        drop(stack_size); // suppress unused warnings w/o async feature
+
         Ok(Self {
             strategy,
             module_limits,
-            instance_limits,
             instances: mem::ManuallyDrop::new(instances),
             #[cfg(all(feature = "async", unix))]
             stacks: StackPool::new(&instance_limits, stack_size)?,
+            #[cfg(all(feature = "async", windows))]
             stack_size,
             #[cfg(all(feature = "uffd", target_os = "linux"))]
             _fault_handler,