Enable some Clippy conversion lints for wasmtime-cranelift

Similar to how `wasmtime::runtime` has a few off-by-default lints turned
on for it do the same for the compilation phase of `wasmtime-cranelift`.
This is intended to help weed out lossy `as` casts and instead steer
users to `from` or `try_from` conversions.

cranelift/codegen/Cargo.toml

@@ -17,7 +17,7 @@ rust-version.workspace = true
 workspace = true
 
 [package.metadata.docs.rs]
-# Ask Cargo to build docs with the feature `all-arch` 
+# Ask Cargo to build docs with the feature `all-arch`
 features = ["all-arch"]
 
 [dependencies]
@@ -62,7 +62,7 @@ default = ["std", "unwind", "host-arch", "timing"]
 # The "std" feature enables use of libstd. The "core" feature enables use
 # of some minimal std-like replacement libraries. At least one of these two
 # features need to be enabled.
-std = []
+std = ["serde?/std"]
 
 # The "core" feature used to enable a hashmap workaround, but is now
 # deprecated (we (i) always use hashbrown, and (ii) don't support a

crates/cranelift/src/compiled_function.rs

@@ -111,7 +111,7 @@ impl CompiledFunction {
             .into_iter()
             .map(|&MachSrcLoc { start, end, loc }| (loc, start, (end - start)));
         let instructions = if with_instruction_addresses {
-            collect_address_maps(len as u32, srclocs)
+            collect_address_maps(len.try_into().unwrap(), srclocs)
         } else {
             Default::default()
         };
@@ -123,7 +123,7 @@ impl CompiledFunction {
             start_srcloc,
             end_srcloc,
             body_offset: 0,
-            body_len: len as u32,
+            body_len: len.try_into().unwrap(),
         };
 
         self.metadata.address_map = address_map;

crates/cranelift/src/compiler.rs

@@ -833,8 +833,8 @@ impl FunctionCompiler<'_> {
             let offset = data.original_position();
             let len = data.bytes_remaining();
             compiled_function.set_address_map(
-                offset as u32,
-                len as u32,
+                offset.try_into().unwrap(),
+                len.try_into().unwrap(),
                 tunables.generate_address_map,
             );
         }

crates/cranelift/src/debug.rs

@@ -1,5 +1,10 @@
 //! Debug utils for WebAssembly using Cranelift.
 
+// FIXME: this whole crate opts-in to these two noisier-than-default lints, but
+// this module has lots of hits on this warning which aren't the easiest to
+// resolve. Ideally all warnings would be resolved here though.
+#![allow(clippy::cast_possible_truncation, clippy::cast_sign_loss)]
+
 use crate::CompiledFunctionMetadata;
 use cranelift_codegen::isa::TargetIsa;
 use object::write::SymbolId;

crates/cranelift/src/func_environ.rs

@@ -952,7 +952,7 @@ impl<'module_environment> FuncEnvironment<'module_environment> {
             .name_section
             .func_names
             .get(&func_index)
-            .map(|s| *s)
+            .copied()
     }
 
     /// Proof-carrying code: create a memtype describing an empty

crates/cranelift/src/lib.rs

@@ -3,6 +3,10 @@
 //! This crate provides an implementation of the `wasmtime_environ::Compiler`
 //! and `wasmtime_environ::CompilerBuilder` traits.
 
+// See documentation in crates/wasmtime/src/runtime.rs for why this is
+// selectively enabled here.
+#![warn(clippy::cast_possible_truncation, clippy::cast_sign_loss)]
+
 use cranelift_codegen::{
     binemit,
     cursor::FuncCursor,

crates/cranelift/src/obj.rs

@@ -26,7 +26,7 @@ use object::{Architecture, SectionKind, SymbolFlags, SymbolKind, SymbolScope};
 use std::collections::HashMap;
 use std::ops::Range;
 use wasmtime_environ::obj::LibCall;
-use wasmtime_environ::Compiler;
+use wasmtime_environ::{Compiler, Unsigned};
 
 const TEXT_SECTION_NAME: &[u8] = b".text";
 
@@ -341,9 +341,9 @@ impl<'a> UnwindInfoBuilder<'a> {
                 let requires_extended_counts = code_words > (1 << 5);
                 let encoded_function_len = function_len / 4;
                 assert!(encoded_function_len < (1 << 18), "function too large");
-                let mut word1 = encoded_function_len as u32;
+                let mut word1 = u32::try_from(encoded_function_len).unwrap();
                 if !requires_extended_counts {
-                    word1 |= (code_words as u32) << 27;
+                    word1 |= u32::from(code_words) << 27;
                 }
                 let unwind_address = self.windows_xdata.len();
                 self.windows_xdata.extend_from_slice(&word1.to_le_bytes());
@@ -548,7 +548,7 @@ impl<'a> UnwindInfoBuilder<'a> {
             // unwinders just use this constant for a relative addition with the
             // address of the FDE, which means that the sign doesn't actually
             // matter.
-            let fde = unwind_info.to_fde(Address::Constant(actual_offset as u64));
+            let fde = unwind_info.to_fde(Address::Constant(actual_offset.unsigned()));
             table.add_fde(cie_id, fde);
         }
         let endian = match compiler.triple().endianness().unwrap() {

crates/cranelift/src/translate/code_translator.rs

@@ -78,7 +78,6 @@ use crate::translate::state::{ControlStackFrame, ElseData, FuncTranslationState}
 use crate::translate::translation_utils::{
     block_with_params, blocktype_params_results, f32_translation, f64_translation,
 };
-use core::{i32, u32};
 use cranelift_codegen::ir::condcodes::{FloatCC, IntCC};
 use cranelift_codegen::ir::immediates::Offset32;
 use cranelift_codegen::ir::types::*;
@@ -93,8 +92,8 @@ use std::collections::{hash_map, HashMap};
 use std::vec::Vec;
 use wasmparser::{FuncValidator, MemArg, Operator, WasmModuleResources};
 use wasmtime_environ::{
-    wasm_unsupported, DataIndex, ElemIndex, FuncIndex, GlobalIndex, MemoryIndex, TableIndex,
-    TypeIndex, WasmRefType, WasmResult,
+    wasm_unsupported, DataIndex, ElemIndex, FuncIndex, GlobalIndex, MemoryIndex, Signed,
+    TableIndex, TypeIndex, Unsigned, WasmRefType, WasmResult,
 };
 
 /// Given a `Reachability<T>`, unwrap the inner `T` or, when unreachable, set
@@ -930,7 +929,7 @@ pub fn translate_operator<FE: FuncEnvironment + ?Sized>(
         }
         /****************************** Nullary Operators ************************************/
         Operator::I32Const { value } => {
-            state.push1(builder.ins().iconst(I32, *value as u32 as i64))
+            state.push1(builder.ins().iconst(I32, i64::from(value.unsigned())));
         }
         Operator::I64Const { value } => state.push1(builder.ins().iconst(I64, *value)),
         Operator::F32Const { value } => {
@@ -3289,9 +3288,7 @@ fn align_atomic_addr<FE: FuncEnvironment + ?Sized>(
         let effective_addr = if memarg.offset == 0 {
             addr
         } else {
-            builder
-                .ins()
-                .iadd_imm(addr, i64::from(memarg.offset as i32))
+            builder.ins().iadd_imm(addr, memarg.offset.signed())
         };
         debug_assert!(loaded_bytes.is_power_of_two());
         let misalignment = builder

crates/cranelift/src/translate/func_translator.rs

@@ -278,6 +278,6 @@ fn parse_function_body<FE: FuncEnvironment + ?Sized>(
 /// Get the current source location from a reader.
 fn cur_srcloc(reader: &BinaryReader) -> ir::SourceLoc {
     // We record source locations as byte code offsets relative to the beginning of the file.
-    // This will wrap around if byte code is larger than 4 GB.
-    ir::SourceLoc::new(reader.original_position() as u32)
+    // This will panic if bytecode is larger than 4 GB.
+    ir::SourceLoc::new(reader.original_position().try_into().unwrap())
 }

crates/wasmtime/src/runtime/vm.rs

@@ -1,6 +1,8 @@
 //! Runtime library support for Wasmtime.
 
 #![deny(missing_docs)]
+// See documentation in crates/wasmtime/src/runtime.rs for why this is
+// selectively enabled here.
 #![warn(clippy::cast_sign_loss)]
 
 use crate::prelude::*;