Use if let instead of match.

https://github.com/rust-lang-nursery/rust-clippy/wiki#single_match

lib/frontend/src/frontend.rs

@@ -147,10 +147,9 @@ impl<'short, 'long, Variable> InstBuilderBase<'short> for FuncInstBuilder<'short
                 }
                 None => {
 // branch_destination() doesn't detect jump_tables
-                    match data {
 // If jump table we declare all entries successor
 // TODO: not collect with vector?
-                        InstructionData::BranchTable { table, .. } => {
+                    if let InstructionData::BranchTable { table, .. } = data {
 // Unlike all other jumps/branches, jump tables are
 // capable of having the same successor appear
 // multiple times. Use a HashSet to deduplicate.
@@ -167,9 +166,6 @@ impl<'short, 'long, Variable> InstBuilderBase<'short> for FuncInstBuilder<'short
                                 self.builder.declare_successor(dest_ebb, inst)
                             }
                     }
-// If not we do nothing
-                        _ => {}
-                    }
                 }
             }
         }

lib/wasm/src/code_translator.rs

@@ -169,13 +169,9 @@ pub fn translate_function_body(
     let mut func = Function::new();
     let args_num: usize = sig.argument_types.len();
     func.signature = sig.clone();
-    match exports {
-        &None => (),
-        &Some(ref exports) => {
-            match exports.get(&function_index) {
-                None => (),
-                Some(name) => func.name = FunctionName::new(name.clone()),
-            }
+    if let Some(ref exports) = *exports {
+        if let Some(name) = exports.get(&function_index) {
+            func.name = FunctionName::new(name.clone());
         }
     }
     let mut func_imports = FunctionImports::new();
@@ -359,12 +355,9 @@ fn translate_operator(
          ***********************************************************************************/
         Operator::Block { ty } => {
             let next = builder.create_ebb();
-            match type_to_type(&ty) {
-                Ok(ty_cre) => {
+            if let Ok(ty_cre) = type_to_type(&ty) {
                 builder.append_ebb_arg(next, ty_cre);
             }
-                Err(_) => {}
-            }
             control_stack.push(ControlStackFrame::Block {
                 destination: next,
                 return_values: translate_type(ty).unwrap(),
@@ -375,12 +368,9 @@ fn translate_operator(
         Operator::Loop { ty } => {
             let loop_body = builder.create_ebb();
             let next = builder.create_ebb();
-            match type_to_type(&ty) {
-                Ok(ty_cre) => {
+            if let Ok(ty_cre) = type_to_type(&ty) {
                 builder.append_ebb_arg(next, ty_cre);
             }
-                Err(_) => {}
-            }
             builder.ins().jump(loop_body, &[]);
             control_stack.push(ControlStackFrame::Loop {
                 destination: next,
@@ -401,12 +391,9 @@ fn translate_operator(
             //   and we add nothing;
             // - either the If have an Else clause, in that case the destination of this jump
             //   instruction will be changed later when we translate the Else operator.
-            match type_to_type(&ty) {
-                Ok(ty_cre) => {
+            if let Ok(ty_cre) = type_to_type(&ty) {
                 builder.append_ebb_arg(if_not, ty_cre);
             }
-                Err(_) => {}
-            }
             control_stack.push(ControlStackFrame::If {
                 destination: if_not,
                 branch_inst: jump_inst,
@@ -1320,14 +1307,12 @@ fn find_function_import(
     exports: &Option<HashMap<FunctionIndex, String>>,
     signatures: &[Signature],
 ) -> FuncRef {
-    match func_imports.functions.get(&index) {
-        Some(local_index) => return *local_index,
-        None => {}
+    if let Some(local_index) = func_imports.functions.get(&index) {
+        return *local_index;
     }
     // We have to import the function
     let sig_index = functions[index];
-    match func_imports.signatures.get(&(sig_index as usize)) {
-        Some(local_sig_index) => {
+    if let Some(local_sig_index) = func_imports.signatures.get(&(sig_index as usize)) {
         let local_func_index = builder.import_function(ExtFuncData {
             name: match exports {
                 &None => FunctionName::new(""),
@@ -1343,8 +1328,6 @@ fn find_function_import(
         func_imports.functions.insert(index, local_func_index);
         return local_func_index;
     }
-        None => {}
-    };
     // We have to import the signature
     let sig_local_index = builder.import_signature(signatures[sig_index as usize].clone());
     func_imports.signatures.insert(
@@ -1373,9 +1356,8 @@ fn find_signature_import(
     func_imports: &mut FunctionImports,
     signatures: &[Signature],
 ) -> SigRef {
-    match func_imports.signatures.get(&(sig_index as usize)) {
-        Some(local_sig_index) => return *local_sig_index,
-        None => {}
+    if let Some(local_sig_index) = func_imports.signatures.get(&(sig_index as usize)) {
+        return *local_sig_index;
     }
     let sig_local_index = builder.import_signature(signatures[sig_index as usize].clone());
     func_imports.signatures.insert(