Remove supports_decompose_bloq (quantumlib#1382)

qualtran/_infra/adjoint.py

@@ -151,10 +151,6 @@ def _circuit_diagram_info_(
         sub_info.exponent *= -1
         return sub_info
 
-    def supports_decompose_bloq(self) -> bool:
-        """Delegate to `subbloq.supports_decompose_bloq()`"""
-        return self.subbloq.supports_decompose_bloq()
-
     def adjoint(self) -> 'Bloq':
         """The 'double adjoint' brings you back to the original bloq."""
         return self.subbloq

qualtran/_infra/adjoint_test.py

@@ -19,7 +19,7 @@
 import qualtran.testing as qlt_testing
 from qualtran import Adjoint, CompositeBloq, Side
 from qualtran._infra.adjoint import _adjoint_cbloq
-from qualtran.bloqs.basic_gates import CNOT, CSwap, ZeroState
+from qualtran.bloqs.basic_gates import CNOT, ZeroState
 from qualtran.bloqs.for_testing.atom import TestAtom
 from qualtran.bloqs.for_testing.with_call_graph import TestBloqWithCallGraph
 from qualtran.bloqs.for_testing.with_decomposition import TestParallelCombo, TestSerialCombo
@@ -101,14 +101,6 @@ def test_adjoint_signature():
     assert adj_reg.side == Side.LEFT
 
 
-def test_adjoint_supports_decompose():
-    assert not CNOT().supports_decompose_bloq()
-    assert not Adjoint(CNOT()).supports_decompose_bloq()
-
-    assert CSwap(bitsize=5).supports_decompose_bloq()
-    assert Adjoint(CSwap(bitsize=5)).supports_decompose_bloq()
-
-
 def test_adjoint_adjoint():
     zero = ZeroState()
     adj = Adjoint(zero)  # specifically use the Adjoint wrapper for testing

qualtran/_infra/bloq.py

@@ -146,15 +146,6 @@ def decompose_bloq(self) -> 'CompositeBloq':
         """
         return _decompose_from_build_composite_bloq(self)
 
-    def supports_decompose_bloq(self) -> bool:
-        """Whether this bloq supports `.decompose_bloq()`.
-
-        By default, we check that the method `build_composite_bloq` is overriden. For
-        extraordinary circumstances, you may need to override this method directly to
-        return an accurate value.
-        """
-        return not self.build_composite_bloq.__qualname__.startswith('Bloq.')
-
     def as_composite_bloq(self) -> 'CompositeBloq':
         """Wrap this Bloq into a size-1 CompositeBloq.
 

qualtran/_infra/bloq_test.py

@@ -36,7 +36,8 @@ def test_bloq():
 
 def test_as_composite_bloq():
     tb = TestAtom()
-    assert not tb.supports_decompose_bloq()
+    with pytest.raises(DecomposeTypeError):
+        tb.decompose_bloq()
     cb = tb.as_composite_bloq()
     assert isinstance(cb, CompositeBloq)
     bloqs = list(cb.bloq_instances)

qualtran/_infra/composite_bloq_test.py

@@ -420,7 +420,6 @@ def test_test_parallel_combo_decomp():
 
 @pytest.mark.parametrize('cls', [TestSerialCombo, TestParallelCombo])
 def test_copy(cls):
-    assert cls().supports_decompose_bloq()
     cbloq = cls().decompose_bloq()
     cbloq2 = cbloq.copy()
     assert cbloq is not cbloq2
@@ -509,9 +508,6 @@ def test_flatten():
     cbloq3 = cbloq.flatten(lambda binst: True)
     assert len(cbloq3.bloq_instances) == 5 * 2
 
-    cbloq4 = cbloq.flatten(lambda binst: binst.bloq.supports_decompose_bloq())
-    assert len(cbloq4.bloq_instances) == 5 * 2
-
     cbloq5 = cbloq.flatten()
     assert len(cbloq5.bloq_instances) == 5 * 2
 

qualtran/bloqs/basic_gates/su2_rotation_test.py

@@ -17,7 +17,6 @@
 
 from qualtran import Bloq
 from qualtran.bloqs.basic_gates import GlobalPhase, Hadamard, Rx, Rz, TGate, XGate, YGate, ZGate
-from qualtran.cirq_interop import BloqAsCirqGate
 
 from .su2_rotation import _hadamard, _su2_rotation_gate, _t_gate, SU2RotationGate
 
@@ -30,7 +29,7 @@ def test_decompose_SU2_to_single_qubit_pauli_gates():
         gate = SU2RotationGate(theta, phi, lambd, global_shift)
 
         np.testing.assert_allclose(
-            cirq.unitary(BloqAsCirqGate(gate.decompose_bloq())), gate.rotation_matrix
+            cirq.unitary(gate.decompose_bloq().to_cirq_circuit()), gate.rotation_matrix
         )
 
 

qualtran/cirq_interop/_bloq_to_cirq.py

@@ -147,14 +147,15 @@ def _decompose_(self, qubits: Sequence[cirq.Qid]) -> cirq.OP_TREE:
         return self._decompose_with_context_(qubits)
 
     def _unitary_(self):
-        if (
-            all(reg.side == Side.THRU for reg in self.signature)
-            and not self.bloq.supports_decompose_bloq()
-        ):
-            tensor = self.bloq.tensor_contract()
-            if tensor.ndim != 2:
+        if all(reg.side == Side.THRU for reg in self.signature):
+            try:
+                _ = self.bloq.decompose_bloq()  # check for decomposability
                 return NotImplemented
-            return tensor
+            except (DecomposeNotImplementedError, DecomposeTypeError):
+                tensor = self.bloq.tensor_contract()
+                if tensor.ndim != 2:
+                    return NotImplemented
+                return tensor
         return NotImplemented
 
     def on_registers(