From 4bdcc20f530ea3e2d0061da3701eaaf5a84e618b Mon Sep 17 00:00:00 2001
From: Matthew Treinish <mtreinish@kortar.org>
Date: Thu, 16 Nov 2023 17:47:30 -0500
Subject: [PATCH] Fix use_symengine ScheduleBlock

---
 qiskit/qpy/binary_io/schedules.py                         | 7 ++++---
 releasenotes/notes/platform-support-f7f693aaf5dec044.yaml | 6 ++++++
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/qiskit/qpy/binary_io/schedules.py b/qiskit/qpy/binary_io/schedules.py
index b0615a3ce966..ce22702c89da 100644
--- a/qiskit/qpy/binary_io/schedules.py
+++ b/qiskit/qpy/binary_io/schedules.py
@@ -104,12 +104,13 @@ def _read_discriminator(file_obj, version):
 def _loads_symbolic_expr(expr_bytes, use_symengine=False):
     if expr_bytes == b"":
         return None
+    expr_bytes = zlib.decompress(expr_bytes)
     if use_symengine:
-        return load_basic(zlib.decompress(expr_bytes))
+        return load_basic(expr_bytes)
     else:
         from sympy import parse_expr
 
-        expr_txt = zlib.decompress(expr_bytes).decode(common.ENCODE)
+        expr_txt = expr_bytes.decode(common.ENCODE)
         expr = parse_expr(expr_txt)
         return sym.sympify(expr)
 
@@ -472,7 +473,7 @@ def _dumps_operand(operand, use_symengine):
 def _write_element(file_obj, element, metadata_serializer, use_symengine):
     if isinstance(element, ScheduleBlock):
         common.write_type_key(file_obj, type_keys.Program.SCHEDULE_BLOCK)
-        write_schedule_block(file_obj, element, metadata_serializer)
+        write_schedule_block(file_obj, element, metadata_serializer, use_symengine)
     else:
         type_key = type_keys.ScheduleInstruction.assign(element)
         common.write_type_key(file_obj, type_key)
diff --git a/releasenotes/notes/platform-support-f7f693aaf5dec044.yaml b/releasenotes/notes/platform-support-f7f693aaf5dec044.yaml
index 2f31d26035a4..9894895e8467 100644
--- a/releasenotes/notes/platform-support-f7f693aaf5dec044.yaml
+++ b/releasenotes/notes/platform-support-f7f693aaf5dec044.yaml
@@ -26,3 +26,9 @@ upgrade:
     build Qiskit from source while the Qiskit MSRV (minimum supported Rust
     version) is < 1.74, but the precompiled binaries published to PyPI will
     only be compatible with macOS >= 10.12.
+
+fixes:
+  - |
+    Fixed an issue with :class:`.qpy.dump` which would cause the function to
+    potentially ignore the value of ``use_symengine`` when serializing a
+    :class:`.ScheduleBlock` object.