🐛 Clear classical bits in resetSimulationState

src/backend/dd/DDSimDebug.cpp

@@ -190,6 +190,11 @@ void resetSimulationState(DDSimulationState* ddsim) {
       dd::makeZeroState(ddsim->qc->getNqubits(), *(ddsim->dd));
   ddsim->dd->incRef(ddsim->simulationState);
   ddsim->paused = false;
+  // Return the classical side to its initial state (all bits false),
+  // matching the quantum state rebuilt above.
+  std::ranges::for_each(
+      ddsim->variables | std::views::values,
+      [](auto& variable) { variable.value.boolValue = false; });
 }
 
 /**

test/test_custom_code.cpp

@@ -279,6 +279,27 @@ TEST_F(CustomCodeTest, ResetGate) {
   ASSERT_TRUE(complexEquality(result, -1.0, 0.0));
 }
 
+/**
+ * @test Test that `resetSimulation` returns the classical side to its initial
+ * state, not just the quantum state.
+ * After running a program that measures `q[0] = |1>` into `c[0]`, `c[0]` holds
+ * `true`; a subsequent `resetSimulation` must set it back to `false`.
+ */
+TEST_F(CustomCodeTest, ResetSimulationClearsClassicalBits) {
+  loadCode(1, 1,
+           "x q[0];"
+           "measure q[0] -> c[0];");
+  ASSERT_EQ(state->runSimulation(state), OK);
+
+  Variable v;
+  ASSERT_EQ(state->getClassicalVariable(state, "c[0]", &v), OK);
+  ASSERT_TRUE(classicalEquals(v, true));
+
+  ASSERT_EQ(state->resetSimulation(state), OK);
+  ASSERT_EQ(state->getClassicalVariable(state, "c[0]", &v), OK);
+  ASSERT_TRUE(classicalEquals(v, false));
+}
+
 /**
  * @test Test that parsing works correctly even if a custom gate name includes
  * the keyword `gate`.