Revert "Delete unreachable/unused attributes"

This reverts commit 67c099f.

Author: lucic71

libcc2rs-macros/src/state_machine.rs

@@ -61,6 +61,7 @@ impl GotoStateMachine {
         };
         quote! {
             #idx => {
+                #[allow(unreachable_code)]
                 { #body; #tail }
             }
         }
@@ -77,6 +78,7 @@ impl GotoStateMachine {
         (
             quote! { let mut #flag: bool = false; },
             quote! {
+                #[allow(unreachable_code)]
                 if #flag { #stmt }
             },
         )
@@ -116,6 +118,7 @@ impl StateMachine for GotoStateMachine {
             #brk_decl
             #cnt_decl
             let mut #s: u32 = 0;
+            #[allow(unreachable_code, unused_labels)]
             #lbl: loop {
                 match #s {
                     #(#body_arms)*
@@ -167,6 +170,7 @@ impl SwitchStateMachine {
         });
         let body: Expr = syn::parse_quote! {
             {
+                #[allow(unreachable_patterns)]
                 match #cond {
                     #(#case_arms,)*
                     _ => break #label,