From 479961bf50768113d2fffd41519483d8f4666c85 Mon Sep 17 00:00:00 2001
From: Seyon Sivarajah <seyon.sivarajah@quantinuum.com>
Date: Wed, 9 Oct 2024 16:04:02 +0100
Subject: [PATCH] feat: return replaced ops from lowering

drive-by: whitespace trimming in yml
---
 .github/workflows/ci-py.yml | 4 ++--
 hugr-passes/src/lower.rs    | 8 ++++----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/ci-py.yml b/.github/workflows/ci-py.yml
index 8fca5e049..6f9e58e78 100644
--- a/.github/workflows/ci-py.yml
+++ b/.github/workflows/ci-py.yml
@@ -58,7 +58,7 @@ jobs:
           enable-cache: true
       - name: Install Python
         run: uv python install ${{ matrix.python-version }}
-        
+
       - name: Setup dependencies. Fail if the lockfile is outdated.
         run: uv sync --locked
 
@@ -106,7 +106,7 @@ jobs:
           - { py: '3.12', coverage: true }
     steps:
       - uses: actions/checkout@v4
-      
+
       - name: Set up uv
         uses: astral-sh/setup-uv@v3
         with:
diff --git a/hugr-passes/src/lower.rs b/hugr-passes/src/lower.rs
index a7e75b355..b799638fc 100644
--- a/hugr-passes/src/lower.rs
+++ b/hugr-passes/src/lower.rs
@@ -55,7 +55,7 @@ pub enum LowerError {
 pub fn lower_ops(
     hugr: &mut impl HugrMut,
     lowering: impl Fn(&OpType) -> Option<Hugr>,
-) -> Result<Vec<Node>, LowerError> {
+) -> Result<Vec<(Node, OpType)>, LowerError> {
     let replacements = hugr
         .nodes()
         .filter_map(|node| {
@@ -69,9 +69,9 @@ pub fn lower_ops(
         .map(|(node, replacement)| {
             let subcirc = SiblingSubgraph::try_from_nodes([node], hugr)?;
             let rw = subcirc.create_simple_replacement(hugr, replacement)?;
-            // TODO return weights once https://github.com/CQCL/hugr/issues/476 is done.
-            hugr.apply_rewrite(rw)?;
-            Ok(node)
+            let mut repls = hugr.apply_rewrite(rw)?;
+            debug_assert_eq!(repls.len(), 1);
+            Ok(repls.remove(0))
         })
         .collect()
 }