Fix all clippy warnings (#564)

* Fix all clippy warnings

* Revert usage of inclusive ranges

* Remove redundant function argument

* Revert use of unavailable pointer methods

* Introduce ContiguousCaseRange

lib/codegen/src/ir/function.rs

@@ -178,19 +178,14 @@ impl Function {
     ///
     /// This function can only be used after the code layout has been computed by the
     /// `binemit::relax_branches()` function.
-    pub fn inst_offsets<'a>(
-        &'a self,
-        func: &'a Function,
-        ebb: Ebb,
-        encinfo: &EncInfo,
-    ) -> InstOffsetIter<'a> {
+    pub fn inst_offsets<'a>(&'a self, ebb: Ebb, encinfo: &EncInfo) -> InstOffsetIter<'a> {
         assert!(
             !self.offsets.is_empty(),
             "Code layout must be computed first"
         );
         InstOffsetIter {
             encinfo: encinfo.clone(),
-            func,
+            func: self,
             divert: RegDiversions::new(),
             encodings: &self.encodings,
             offset: self.offsets[ebb],