Fix bug in QPY symengine payload version handling

qiskit/qpy/__init__.py

@@ -118,11 +118,11 @@
 
 .. note::
 
-    With versions of Qiskit before 1.2.3, the ``use_symengine=True`` argument to :func:`.qpy.dump`
+    With versions of Qiskit before 1.2.4, the ``use_symengine=True`` argument to :func:`.qpy.dump`
     could cause problems with backwards compatibility if there were :class:`.ParameterExpression`
     objects to serialize.  In particular:
 
-    * When the loading version of Qiskit is 1.2.3 or greater, QPY files generated with any version
+    * When the loading version of Qiskit is 1.2.4 or greater, QPY files generated with any version
       of Qiskit >= 0.46.0 can be loaded.  If a version of Qiskit between 0.45.0 and 0.45.3 was used
       to generate the files, and the non-default argument ``use_symengine=True`` was given to
       :func:`.qpy.dump`, the file can only be read if the version of ``symengine`` used in the
@@ -134,7 +134,7 @@
       used in the generating environment.
 
     To recover a QPY file that fails with ``symengine`` version-related errors during a call to
-    :func:`.qpy.load`, first attempt to use Qiskit >= 1.2.3 to load the file.  If this still fails,
+    :func:`.qpy.load`, first attempt to use Qiskit >= 1.2.4 to load the file.  If this still fails,
     it is likely because Qiskit 0.45.x was used to generate the file with ``use_symengine=True``.
     In this case, use Qiskit 0.45.3 with ``symengine==0.9.2`` to load the file, and then re-export
     it to QPY setting ``use_symengine=False``.  The resulting file can then be loaded by any later

qiskit/qpy/common.py

@@ -322,7 +322,7 @@ def load_symengine_payload(payload: bytes) -> symengine.Expr:
     major = payload[2]
     minor = payload[3]
     if int(symengine_version[1]) != minor:
-        if major != "0":
+        if major != 0:
             raise exceptions.QpyError(
                 "Qiskit doesn't support loading a symengine payload generated with symengine >= 1.0"
             )

qiskit/qpy/interface.py

@@ -149,7 +149,7 @@ def dump(
                 If serializing a :class:`.QuantumCircuit` or :class:`.ScheduleBlock` that contain
                 :class:`.ParameterExpression` objects with ``version`` set low with the intent to
                 load the payload using a historical release of Qiskit, it is safest to set the
-                ``use_symengine`` flag to ``False``.  Versions of Qiskit prior to 1.2.3 cannot load
+                ``use_symengine`` flag to ``False``.  Versions of Qiskit prior to 1.2.4 cannot load
                 QPY files containing ``symengine``-serialized :class:`.ParameterExpression` objects
                 unless the version of ``symengine`` used between the loading and generating
                 environments matches.

releasenotes/notes/fix-qpy-parsing-123-75357c3709e35963.yaml

@@ -0,0 +1,10 @@
+---
+fixes:
+  - |
+    Fixed an issue introduced in the now
+    `yanked <https://peps.python.org/pep-0592/>`__ 1.2.3 bugfix release that
+    would cause an exception with the error message "Qiskit doesn't support
+    loading a symengine payload generated with symengine >= 1.0" to be raised
+    whenever loading a QPY file that was generated with a different symengine
+    version from the version installed by the loading. This issue could only
+    occur in 1.2.3.

releasenotes/notes/fix-qpy-symengine-compat-858970a9a1d6bc14.yaml

@@ -15,7 +15,7 @@ fixes:
     work.
 issues:
   - |
-    Versions of Qiskit before 1.2.3 will not be able to load QPY files dumped
+    Versions of Qiskit before 1.2.4 will not be able to load QPY files dumped
     using :func:`.qpy.dump`, even with ``version`` set appropriately, if:
 
     * there are unbound :class:`.ParameterExpression`\ s in the QPY file,
@@ -25,15 +25,15 @@ issues:
       environments are not within the same minor version.
 
     This applies regardless of the version of Qiskit used in the generation (at
-    least up to Qiskit 1.2.3 inclusive).
+    least up to Qiskit 1.2.4 inclusive).
 
     If you want to maximize compatibility with older versions of Qiskit, you
     should set ``use_symengine=False``.  Newer versions of Qiskit should not
     require this.
   - |
     QPY files from the Qiskit 0.45 series can, under a very specific and unlikely
     set of circumstances, fail to load with any newer version of Qiskit,
-    including Qiskit 1.2.3.  The criteria are:
+    including Qiskit 1.2.4.  The criteria are:
 
     * the :class:`.QuantumCircuit` or :class:`.ScheduleBlock` to be dumped
       contained unbound :class:`.ParameterExpression` objects,

test/qpy_compat/get_versions.py

@@ -70,7 +70,7 @@ def available_versions_for_package(package, min_version=None, max_version=None):
             if not any(
                 tag in supported_tags
                 for release in payload
-                if release["packagetype"] == "bdist_wheel"
+                if release["packagetype"] == "bdist_wheel" and not release["yanked"]
                 for tag in tags_from_wheel_name(release["filename"])
             ):
                 print(

test/qpy_compat/run_tests.sh

@@ -26,11 +26,30 @@ qiskit_venv="$(pwd -P)/qiskit_venv"
 qiskit_python="$qiskit_venv/bin/python"
 python -m venv "$qiskit_venv"
 # `packaging` is needed for the `get_versions.py` script.
-"$qiskit_venv/bin/pip" install -c "$our_dir/../../constraints.txt" "$our_dir/../.." packaging
+#  symengine is pinned to 0.13 to explicitly test the migration path reusing the venv
+"$qiskit_venv/bin/pip" install -c "$our_dir/../../constraints.txt" "$our_dir/../.." packaging "symengine~=0.13"
 
 "$qiskit_python" "$our_dir/get_versions.py" | parallel --colsep=" " bash "$our_dir/process_version.sh" -p "$qiskit_python"
 
 # Test dev compatibility
 dev_version="$("$qiskit_python" -c 'import qiskit; print(qiskit.__version__)')"
 "$qiskit_python" "$our_dir/test_qpy.py" generate --version="$dev_version"
 "$qiskit_python" "$our_dir/test_qpy.py" load --version="$dev_version"
+
+# Test dev compatibility with different symengine versions across 0.11 and 0.13
+#
+# NOTE: When symengine >= 0.14.0 is released we will need to modify this to build an explicit
+# symengine 0.13.0 venv instead of reusing $qiskit_venv.
+#
+symengine_11_venv="$(pwd -P)/qiskit_symengine_11_venv"
+symengine_11_python="$symengine_11_venv/bin/python"
+python -m venv "$symengine_11_venv"
+"$symengine_11_venv/bin/pip" install -c "$our_dir/../../constraints.txt" "$our_dir/../.." "symengine==0.11.0"
+# Load symengine 0.13.0 generated payload with symengine 0.11
+"$symengine_11_python" "$our_dir/test_qpy.py" load --version="$dev_version"
+# Load symengine 0.11.0 generated payload with symengine 0.13.0
+mkdir symengine_11_qpy_files
+pushd symengine_11_qpy_files
+"$symengine_11_python" "$our_dir/test_qpy.py" generate --version="$dev_version"
+"$qiskit_python" "$our_dir/test_qpy.py" load --version="$dev_version"
+popd