add clippy rules for ff-macros crate (#931)

Author: tcoratger

ff-macros/Cargo.toml

@@ -13,12 +13,15 @@ edition.workspace = true
 rust-version.workspace = true
 metadata.docs.rs.workspace = true
 package.metadata.release.workspace = true
-keywords = ["cryptography", "finite-fields", "assembly" ]
+keywords = ["cryptography", "finite-fields", "assembly"]
+
+[lints]
+workspace = true
 
 [dependencies]
 quote.workspace = true
 proc-macro2.workspace = true
-syn = { workspace = true, features = ["full", "parsing", "extra-traits"]}
+syn = { workspace = true, features = ["full", "parsing", "extra-traits"] }
 num-bigint.workspace = true
 num-traits.workspace = true
 

ff-macros/src/lib.rs

@@ -120,9 +120,8 @@ fn fetch_attr(name: &str, attrs: &[syn::Attribute]) -> Option<String> {
                 }) = nv.value
                 {
                     return Some(s.value());
-                } else {
-                    panic!("attribute {name} should be a string")
                 }
+                panic!("attribute {name} should be a string")
             },
             _ => continue,
         }
@@ -131,6 +130,7 @@ fn fetch_attr(name: &str, attrs: &[syn::Attribute]) -> Option<String> {
 }
 
 #[test]
+#[allow(clippy::match_same_arms)]
 fn test_str_to_limbs() {
     use num_bigint::Sign::*;
     for i in 0..100 {

ff-macros/src/montgomery/mod.rs

@@ -21,7 +21,7 @@ use sum_of_products::sum_of_products_impl;
 
 use crate::utils;
 
-pub fn mont_config_helper(
+pub(crate) fn mont_config_helper(
     modulus: BigUint,
     generator: BigUint,
     small_subgroup_base: Option<u32>,
@@ -60,10 +60,10 @@ pub fn mont_config_helper(
     let modulus_has_spare_bit = modulus_limbs.last().unwrap() >> 63 == 0;
     let can_use_no_carry_mul_opt = {
         let first_limb_check = *modulus_limbs.last().unwrap() < (u64::MAX >> 1);
-        if limbs != 1 {
-            first_limb_check && modulus_limbs[..limbs - 1].iter().any(|l| *l != u64::MAX)
-        } else {
+        if limbs == 1 {
             first_limb_check
+        } else {
+            first_limb_check && modulus_limbs[..limbs - 1].iter().any(|l| *l != u64::MAX)
         }
     };
     let modulus = quote::quote! { BigInt([ #( #modulus_limbs ),* ]) };

ff-macros/src/unroll.rs

@@ -65,7 +65,7 @@ pub(crate) fn unroll_in_block(block: &Block, unroll_by: usize) -> Block {
         ref stmts,
     } = block;
     let mut new_stmts = Vec::new();
-    for stmt in stmts.iter() {
+    for stmt in stmts {
         if let Stmt::Expr(expr, semi) = stmt {
             new_stmts.push(Stmt::Expr(unroll(expr, unroll_by), *semi));
         } else {

ff-macros/src/utils.rs

@@ -5,7 +5,7 @@ use num_traits::Num;
 use proc_macro::TokenStream;
 use syn::{Expr, Lit};
 
-pub fn parse_string(input: TokenStream) -> Option<String> {
+pub(crate) fn parse_string(input: TokenStream) -> Option<String> {
     let input: Expr = syn::parse(input).unwrap();
     let input = if let Expr::Group(syn::ExprGroup { expr, .. }) = input {
         expr
@@ -21,12 +21,12 @@ pub fn parse_string(input: TokenStream) -> Option<String> {
     }
 }
 
-pub fn str_to_limbs(num: &str) -> (bool, Vec<String>) {
+pub(crate) fn str_to_limbs(num: &str) -> (bool, Vec<String>) {
     let (sign, limbs) = str_to_limbs_u64(num);
     (sign, limbs.into_iter().map(|l| format!("{l}u64")).collect())
 }
 
-pub fn str_to_limbs_u64(num: &str) -> (bool, Vec<u64>) {
+pub(crate) fn str_to_limbs_u64(num: &str) -> (bool, Vec<u64>) {
     let is_negative = num.starts_with('-');
     let num = if is_negative { &num[1..] } else { num };
     let number = if num.starts_with("0x") || num.starts_with("0X") {