feat: Deprecate local find_tuple_unpack rewrite (#1188)

We moved the untuple rewrite into a hugr pass
(https://docs.rs/hugr/latest/hugr/algorithms/struct.UntuplePass.html),
but never removed it from here.

Author: aborgna-q

tket/src/passes.rs

@@ -11,6 +11,7 @@ pub mod pytket;
 pub use pytket::lower_to_pytket;
 
 pub mod tuple_unpack;
+#[allow(deprecated)]
 pub use tuple_unpack::find_tuple_unpack_rewrites;
 
 pub mod unpack_container;

tket/src/passes/pytket.rs

@@ -4,14 +4,13 @@
 //! This is a best-effort attempt, and may not always succeed.
 
 use derive_more::{Display, Error, From};
+use hugr::algorithms::untuple::{UntupleError, UntupleRecursive};
+use hugr::algorithms::{ComposablePass, UntuplePass};
 use hugr::{HugrView, Node};
-use itertools::Itertools;
 
 use crate::serialize::pytket::OpConvertError;
 use crate::Circuit;
 
-use super::find_tuple_unpack_rewrites;
-
 /// Try to lower a circuit to a form that can be encoded as a pytket legacy circuit.
 pub fn lower_to_pytket<T: HugrView<Node = Node>>(
     circ: &Circuit<T>,
@@ -22,10 +21,7 @@ pub fn lower_to_pytket<T: HugrView<Node = Node>>(
 
     // Remove sequences of tuple pack-unpack operations,
     // typically generated by guppy.
-    let rewrites = find_tuple_unpack_rewrites(&circ).collect_vec();
-    for rewrite in rewrites {
-        rewrite.apply(&mut circ).unwrap();
-    }
+    UntuplePass::new(UntupleRecursive::NonRecursive).run(circ.hugr_mut())?;
 
     Ok(circ)
 }
@@ -42,6 +38,10 @@ pub enum PytketLoweringError {
     /// Function calls are not supported.
     #[display("Non-local operations found. Function calls are not supported.")]
     NonLocalOperations,
+    /// An error occurred during the untuple pass.
+    #[display("untuple pass error: {_0}")]
+    #[from]
+    UntupleError(UntupleError),
 }
 
 #[cfg(test)]

tket/src/passes/tuple_unpack.rs

@@ -16,6 +16,7 @@ use crate::Circuit;
 
 /// Find tuple pack operations followed by tuple unpack operations
 /// and generate rewrites to remove them.
+#[deprecated(since = "0.15.1", note = "Use hugr::algorithms::UntuplePass instead")]
 pub fn find_tuple_unpack_rewrites(
     circ: &Circuit<impl HugrView<Node = Node>>,
 ) -> impl Iterator<Item = CircuitRewrite> + '_ {
@@ -239,6 +240,7 @@ mod test {
     ) -> Result<(), Box<dyn std::error::Error>> {
         let mut num_rewrites = 0;
         loop {
+            #[allow(deprecated)]
             let Some(rewrite) = find_tuple_unpack_rewrites(&circ).next() else {
                 break;
             };