poseidon: Return CellValue from squeeze()

src/circuit.rs

@@ -488,12 +488,10 @@ impl plonk::Circuit<pallas::Base> for Circuit {
                     layouter.namespace(|| "Poseidon init"),
                     ConstantLength::<2>,
                 )?;
-                let poseidon_output = poseidon_hasher.hash(
+                poseidon_hasher.hash(
                     layouter.namespace(|| "Poseidon hash (nk, rho_old)"),
                     poseidon_message,
-                )?;
-                let poseidon_output: CellValue<pallas::Base> = poseidon_output.inner().into();
-                poseidon_output
+                )?
             };
 
             // Add hash output to psi.

src/circuit/gadget/poseidon.rs

@@ -20,7 +20,7 @@ pub trait PoseidonInstructions<F: FieldExt, S: Spec<F, T, RATE>, const T: usize,
     Chip<F>
 {
     /// Variable representing the word over which the Poseidon permutation operates.
-    type Word: Copy + fmt::Debug + From<CellValue<F>>;
+    type Word: Copy + fmt::Debug + From<CellValue<F>> + Into<CellValue<F>>;
 
     /// Applies the Poseidon permutation to the given state.
     fn permute(
@@ -182,10 +182,7 @@ impl<
     }
 
     /// Squeezes an element from the sponge.
-    pub fn squeeze(
-        &mut self,
-        mut layouter: impl Layouter<F>,
-    ) -> Result<Word<F, PoseidonChip, S, T, RATE>, Error> {
+    pub fn squeeze(&mut self, mut layouter: impl Layouter<F>) -> Result<CellValue<F>, Error> {
         loop {
             match self.sponge {
                 Sponge::Absorbing(ref input) => {
@@ -200,7 +197,7 @@ impl<
                 Sponge::Squeezing(ref mut output) => {
                     for entry in output.iter_mut() {
                         if let Some(inner) = entry.take() {
-                            return Ok(Word { inner });
+                            return Ok(inner.into());
                         }
                     }
 
@@ -253,7 +250,7 @@ impl<
         mut self,
         mut layouter: impl Layouter<F>,
         message: [CellValue<F>; L],
-    ) -> Result<Word<F, PoseidonChip, S, T, RATE>, Error> {
+    ) -> Result<CellValue<F>, Error> {
         for (i, value) in array::IntoIter::new(message).enumerate() {
             self.duplex
                 .absorb(layouter.namespace(|| format!("absorb_{}", i)), value)?;

src/circuit/gadget/poseidon/pow5t3.rs

@@ -821,8 +821,7 @@ mod tests {
                         0,
                         || self.output.ok_or(Error::SynthesisError),
                     )?;
-                    let word: StateWord<_> = output.inner;
-                    region.constrain_equal(word.var, expected_var)
+                    region.constrain_equal(output.cell(), expected_var)
                 },
             )
         }