From ea258fe4f05f5436aae8b74ca09c6ae7391fede5 Mon Sep 17 00:00:00 2001
From: Graham Enos <genos@rigetti.com>
Date: Tue, 20 Sep 2022 18:19:08 -0400
Subject: [PATCH] Fix: Ensure adding programs doesn't mutate the first

Closes #1476

As noted in #1476, adding programs (like `p1 + p2`) currently mutates
the first program (i.e. `p1` would change). This PR ensures that
calibrations et. al. are copied rather than just assigned, and adds a
new test case to `unit/test_program.py` to ensure against regression:

```shell
$ poetry run pytest test/unit/test_program.py --verbose
==================================== test session starts =====================================
platform darwin -- Python 3.9.13, pytest-6.2.4, py-1.10.0, pluggy-0.13.1 -- /Users/genos/rc/repos/pyquil/.venv/bin/python
cachedir: .pytest_cache
rootdir: /Users/genos/rc/repos/pyquil
plugins: cov-2.12.1, freezegun-0.4.2, rerunfailures-9.1.1, xdist-2.3.0, mock-3.6.1, timeout-1.4.2, forked-1.3.0
collected 5 items

test/unit/test_program.py::test_measure_qubits PASSED                                  [ 20%]
test/unit/test_program.py::test_parameterized_single_qubit_measurement_basis PASSED    [ 40%]
test/unit/test_program.py::test_parameterized_single_qubit_state_preparation PASSED    [ 60%]
test/unit/test_program.py::test_parameterized_readout_symmetrization PASSED            [ 80%]
test/unit/test_program.py::test_adding_does_not_mutate PASSED                          [100%]
```
---
 pyquil/quil.py            |  6 +++---
 test/unit/test_program.py | 28 ++++++++++++++++++++++++++++
 test/unit/test_quil.py    |  0
 3 files changed, 31 insertions(+), 3 deletions(-)
 mode change 100755 => 100644 test/unit/test_quil.py

diff --git a/pyquil/quil.py b/pyquil/quil.py
index 2fabf8642..15fd7b56c 100644
--- a/pyquil/quil.py
+++ b/pyquil/quil.py
@@ -874,9 +874,9 @@ def __add__(self, other: InstructionDesignator) -> "Program":
         p = Program()
         p.inst(self)
         p.inst(other)
-        p._calibrations = self.calibrations
-        p._waveforms = self.waveforms
-        p._frames = self.frames
+        p._calibrations = self.calibrations.copy()
+        p._waveforms = self.waveforms.copy()
+        p._frames = self.frames.copy()
         p._memory = self._memory.copy()
         if isinstance(other, Program):
             p.calibrations.extend(other.calibrations)
diff --git a/test/unit/test_program.py b/test/unit/test_program.py
index b4a474792..06d2bab7c 100644
--- a/test/unit/test_program.py
+++ b/test/unit/test_program.py
@@ -56,3 +56,31 @@ def test_parameterized_readout_symmetrization():
     p += RX(symmetrization[0], 0)
     p += RX(symmetrization[1], 1)
     assert parameterized_readout_symmetrization([0, 1]).out() == p.out()
+
+
+def test_adding_does_not_mutate():
+    # https://github.com/rigetti/pyquil/issues/1476
+    p1 = Program(
+        """
+DEFCAL RX(pi/2) 32:
+    FENCE 32
+    NONBLOCKING PULSE 32 "rf" drag_gaussian(duration: 3.2e-08, fwhm: 8e-09, t0: 1.6e-08, anh: -190000000.0, alpha: -1.8848698349348032, scale: 0.30631340170943533, phase: 0.0, detuning: 1622438.2425563578)
+    FENCE 32
+
+RX(pi/2) 32
+"""
+    )
+    original_p1 = p1.copy()
+    p2 = Program(
+        """
+DEFCAL RX(pi/2) 33:
+    FENCE 33
+    NONBLOCKING PULSE 33 "rf" drag_gaussian(duration: 2e-08, fwhm: 5e-09, t0: 1e-08, anh: -190000000.0, alpha: -0.9473497322033984, scale: 0.25680107985232403, phase: 0.0, detuning: 1322130.5458282642)
+    FENCE 33
+
+RX(pi/2) 33
+"""
+    )
+    p_all = p1 + p2
+    assert p1 == original_p1
+    assert p1.calibrations != p_all.calibrations
diff --git a/test/unit/test_quil.py b/test/unit/test_quil.py
old mode 100755
new mode 100644