reno

releasenotes/notes/transpiling_basis_none-b2f1abdb3c080eca.yaml

@@ -0,0 +1,27 @@
+---
+fixes:
+  - |
+    Bug #3017 is fixed. The function ``qiskit.compiler.transpile()`` honors the parameter ``basis_gates=None`` 
+    to allow any gate in the final tranpiled circuit, including gates added by the transpilation process.
+    This might also have some unintended consequences during optimization. For example,
+    :class:`qiskit.transpiler.passes.Optimize1qGates` only optimizes the chains of u1, u2, and u3 gates:
+
+    .. code-block:: python
+
+      from qiskit import *
+      
+      q = QuantumRegister(1, name='q')
+      circuit = QuantumCircuit(q)
+      circuit.h(q[0])
+      circuit.u1(0.1, q[0])
+      circuit.u2(0.1, 0.2, q[0])
+      circuit.h(q[0])
+      circuit.u3(0.1, 0.2, 0.3, q[0])
+      
+      result = transpile(circuit, basis_gates=None, optimization_level=3)
+      result.draw()
+
+    .. parsed-literal::
+          ┌───┐┌─────────────┐┌───┐┌─────────────────┐
+     q_0: ┤ H ├┤ U2(0.1,0.3) ├┤ H ├┤ U3(0.1,0.2,0.3) ├
+          └───┘└─────────────┘└───┘└─────────────────┘