fix cargo doc warnings (#417)

src/backends/plonky2/primitives/ec/curve.rs

@@ -42,7 +42,7 @@ type ECField = QuinticExtension<GoldilocksField>;
 /// Computes sqrt in ECField as sqrt(x) = sqrt(x^r)/x^((r-1)/2) with r
 /// = 1 + p + ... + p^4, where the numerator involves a sqrt in
 /// GoldilocksField, cf.
-/// https://github.com/pornin/ecgfp5/blob/ce059c6d1e1662db437aecbf3db6bb67fe63c716/rust/src/field.rs#L1041
+/// <https://github.com/pornin/ecgfp5/blob/ce059c6d1e1662db437aecbf3db6bb67fe63c716/rust/src/field.rs#L1041>
 pub fn ec_field_sqrt(x: &ECField) -> Option<ECField> {
     // Compute x^r.
     let x_to_the_r = (0..5)

src/backends/plonky2/primitives/ec/gates/curve.rs

@@ -41,10 +41,10 @@ use crate::backends::plonky2::{
 /// allocation of operations to gates via the `current_slots` field.  Once the circuit is fully
 /// defined, during the build the circuit the generators
 /// associated to unused operations (free slots) are removed:
-/// https://github.com/0xPolygonZero/plonky2/blob/82791c4809d6275682c34b926390ecdbdc2a5297/plonky2/src/plonk/circuit_builder.rs#L1210
+/// <https://github.com/0xPolygonZero/plonky2/blob/82791c4809d6275682c34b926390ecdbdc2a5297/plonky2/src/plonk/circuit_builder.rs#L1210>
 /// Since the generator for the unused operations are removed, no witness value will be calculated
 /// for them, and the free slots gate witness wires will be filled with the default value which is zero:
-/// https://github.com/0xPolygonZero/plonky2/blob/82791c4809d6275682c34b926390ecdbdc2a5297/plonky2/src/iop/witness.rs#L377
+/// <https://github.com/0xPolygonZero/plonky2/blob/82791c4809d6275682c34b926390ecdbdc2a5297/plonky2/src/iop/witness.rs#L377>
 /// This means that a gate with multiple operations need to pass the constraints for a single
 /// operation when all its witness wire values are zero (so that when the gate is partially used,
 /// the unused slots still pass the constraints). This is the reason why this gate doesn't add the

src/backends/plonky2/primitives/merkletree/mod.rs

@@ -1,5 +1,5 @@
 //! Module that implements the MerkleTree specified at
-//! https://0xparc.github.io/pod2/merkletree.html .
+//! <https://0xparc.github.io/pod2/merkletree.html> .
 use std::{collections::HashMap, fmt, iter::IntoIterator};
 
 use itertools::zip_eq;
@@ -14,7 +14,7 @@ pub mod error;
 pub use error::{TreeError, TreeResult};
 
 /// Implements the MerkleTree specified at
-/// https://0xparc.github.io/pod2/merkletree.html
+/// <https://0xparc.github.io/pod2/merkletree.html>
 #[derive(Clone, Debug)]
 pub struct MerkleTree {
     max_depth: usize,

src/backends/plonky2/primitives/signature/mod.rs

@@ -1,5 +1,5 @@
 //! Proof-based signatures using Plonky2 proofs, following
-//! https://eprint.iacr.org/2024/1553 .
+//! <https://eprint.iacr.org/2024/1553> .
 
 pub mod circuit;
 pub use circuit::*;

src/middleware/containers.rs

@@ -1,5 +1,5 @@
 //! This file implements the types defined at
-//! https://0xparc.github.io/pod2/values.html#dictionary-array-set .
+//! <https://0xparc.github.io/pod2/values.html#dictionary-array-set> .
 
 use std::collections::{HashMap, HashSet};
 

src/middleware/mod.rs

@@ -989,6 +989,6 @@ pub trait MainPodProver {
 }
 
 pub trait ToFields {
-    /// returns Vec<F> representation of the type
+    /// returns `Vec<F>` representation of the type
     fn to_fields(&self, params: &Params) -> Vec<F>;
 }

src/middleware/operation.rs

@@ -50,8 +50,8 @@ impl fmt::Display for OperationAux {
 
 impl ToFields for OperationType {
     /// Encoding:
-    /// - Native(native_op) => [1, [native_op], 0, 0, 0, 0]
+    /// - Native(native_op) => `[1, [native_op], 0, 0, 0, 0]`
-    /// - Custom(batch, index) => [3, [batch.id], index]
+    /// - Custom(batch, index) => `[3, [batch.id], index]`
     fn to_fields(&self, params: &Params) -> Vec<F> {
         let mut fields: Vec<F> = match self {
             Self::Native(p) => iter::once(F::from_canonical_u64(1))

src/middleware/statement.rs

@@ -485,10 +485,10 @@ impl StatementArg {
 
 impl ToFields for StatementArg {
     /// Encoding:
-    /// - None => [0, 0, 0, 0, 0, 0, 0, 0]
+    /// - None => `[0, 0, 0, 0, 0, 0, 0, 0]`
-    /// - Literal(v) => [[v], 0, 0, 0, 0]
+    /// - Literal(v) => `[[v], 0, 0, 0, 0]`
-    /// - Key(root, key) => [[root], [key]]
+    /// - Key(root, key) => `[[root], [key]]`
-    /// - WildcardLiteral(v) => [[v], 0, 0, 0, 0]
+    /// - WildcardLiteral(v) => `[[v], 0, 0, 0, 0]`
     fn to_fields(&self, params: &Params) -> Vec<F> {
         // NOTE for @ax0: I removed the old comment because may `to_fields` implementations do
         // padding and we need fixed output length for the circuits.