Fix no_std support in cranelift/frontend

cranelift/frontend/src/frontend.rs

@@ -1,7 +1,7 @@
 //! A frontend for building Cranelift IR from other languages.
 use crate::ssa::{SSABuilder, SideEffects};
 use crate::variable::Variable;
-use alloc::vec::Vec;
+use alloc::{vec, vec::Vec};
 use core::fmt::{self, Debug};
 use cranelift_codegen::cursor::{Cursor, CursorPosition, FuncCursor};
 use cranelift_codegen::entity::{EntityRef, EntitySet, PrimaryMap, SecondaryMap};
@@ -242,7 +242,7 @@ impl fmt::Display for UseVariableError {
     }
 }
 
-impl std::error::Error for UseVariableError {}
+impl core::error::Error for UseVariableError {}
 
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 /// An error encountered when defining the initial value of a variable.
@@ -1107,8 +1107,8 @@ impl<'a> FunctionBuilder<'a> {
         left: Value,
         right: Value,
         size: u64,
-        left_align: std::num::NonZeroU8,
-        right_align: std::num::NonZeroU8,
+        left_align: core::num::NonZeroU8,
+        right_align: core::num::NonZeroU8,
         flags: MemFlags,
     ) -> Value {
         use IntCC::*;

cranelift/frontend/src/ssa.rs

@@ -8,7 +8,7 @@
 //! <https://link.springer.com/content/pdf/10.1007/978-3-642-37051-9_6.pdf>
 
 use crate::Variable;
-use alloc::vec::Vec;
+use alloc::{vec, vec::Vec};
 use core::mem;
 use cranelift_codegen::cursor::{Cursor, FuncCursor};
 use cranelift_codegen::entity::{EntityList, EntitySet, ListPool, SecondaryMap};

cranelift/frontend/src/switch.rs

@@ -1,6 +1,6 @@
 use super::HashMap;
 use crate::frontend::FunctionBuilder;
-use alloc::vec::Vec;
+use alloc::{vec, vec::Vec};
 use cranelift_codegen::ir::condcodes::IntCC;
 use cranelift_codegen::ir::*;