Remove deprecated functionality from extensions, qasm, and dagcircuit…

… modules (#7208)

* Remove deprecated functionality

This commit goes through qiskit.extensions, qiskit.qasm, qiskit.util,
and qiskit.dagcircuit modules and cleans up deprecated functionality
that has gone through a full deprecation cycle and no longer needs to
be supported.

* Restore qiskit/util.py

The qiskit/util.py will need to be deprecated a bit longer it's still in
active use by downstream packages and it was right on the boundary of
being deprecated long enough anyway so being a bit more conservative on
this is probably for the best anyway.

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

qiskit/dagcircuit/dagcircuit.py

@@ -23,7 +23,6 @@
 from collections import OrderedDict, defaultdict
 import copy
 import itertools
-import warnings
 import math
 
 import numpy as np
@@ -628,36 +627,7 @@ def _map_condition(wire_map, condition, target_cregs):
             new_condition = (new_creg, new_cond_val)
         return new_condition
 
-    def extend_back(self, dag, edge_map=None):
-        """DEPRECATED: Add `dag` at the end of `self`, using `edge_map`."""
-        warnings.warn(
-            "dag.extend_back is deprecated, please use dag.compose.",
-            DeprecationWarning,
-            stacklevel=2,
-        )
-        edge_map = edge_map or {}
-        for qreg in dag.qregs.values():
-            if qreg.name not in self.qregs:
-                self.add_qreg(QuantumRegister(qreg.size, qreg.name))
-            edge_map.update([(qbit, qbit) for qbit in qreg if qbit not in edge_map])
-
-        for creg in dag.cregs.values():
-            if creg.name not in self.cregs:
-                self.add_creg(ClassicalRegister(creg.size, creg.name))
-            edge_map.update([(cbit, cbit) for cbit in creg if cbit not in edge_map])
-
-        self.compose_back(dag, edge_map)
-
-    def compose_back(self, input_circuit, edge_map=None):
-        """DEPRECATED: use DAGCircuit.compose() instead."""
-        warnings.warn(
-            "dag.compose_back is deprecated, please use dag.compose.",
-            DeprecationWarning,
-            stacklevel=2,
-        )
-        self.compose(input_circuit, edge_map)
-
-    def compose(self, other, edge_map=None, qubits=None, clbits=None, front=False, inplace=True):
+    def compose(self, other, qubits=None, clbits=None, front=False, inplace=True):
         """Compose the ``other`` circuit onto the output of this circuit.
 
         A subset of input wires of ``other`` are mapped
@@ -667,9 +637,6 @@ def compose(self, other, edge_map=None, qubits=None, clbits=None, front=False, i
 
         Args:
             other (DAGCircuit): circuit to compose with self
-            edge_map (dict): DEPRECATED - a {Bit: Bit} map from input wires of other
-                to output wires of self (i.e. rhs->lhs).
-                The key, value pairs can be either Qubit or Clbit mappings.
             qubits (list[Qubit|int]): qubits of self to compose onto.
             clbits (list[Clbit|int]): clbits of self to compose onto.
             front (bool): If True, front composition will be performed (not implemented yet)
@@ -689,15 +656,6 @@ def compose(self, other, edge_map=None, qubits=None, clbits=None, front=False, i
                 "Trying to compose with another DAGCircuit which has more 'in' edges."
             )
 
-        if edge_map is not None:
-            warnings.warn(
-                "edge_map arg as a dictionary is deprecated. "
-                "Use qubits and clbits args to specify a list of "
-                "self edges to compose onto.",
-                DeprecationWarning,
-                stacklevel=2,
-            )
-
         # number of qubits and clbits must match number in circuit or None
         identity_qubit_map = dict(zip(other.qubits, self.qubits))
         identity_clbit_map = dict(zip(other.clbits, self.clbits))
@@ -725,7 +683,7 @@ def compose(self, other, edge_map=None, qubits=None, clbits=None, front=False, i
                 other.clbits[i]: (self.clbits[c] if isinstance(c, int) else c)
                 for i, c in enumerate(clbits)
             }
-        edge_map = edge_map or {**qubit_map, **clbit_map} or None
+        edge_map = {**qubit_map, **clbit_map} or None
 
         # if no edge_map, try to do a 1-1 mapping in order
         if edge_map is None:
@@ -1359,34 +1317,6 @@ def named_nodes(self, *names):
                 named_nodes.append(node)
         return named_nodes
 
-    def twoQ_gates(self):
-        """Get list of 2-qubit gates. Ignore snapshot, barriers, and the like."""
-        warnings.warn(
-            "deprecated function, use dag.two_qubit_ops(). "
-            "filter output by isinstance(op, Gate) to only get unitary Gates.",
-            DeprecationWarning,
-            stacklevel=2,
-        )
-        two_q_gates = []
-        for node in self.gate_nodes():
-            if len(node.qargs) == 2:
-                two_q_gates.append(node)
-        return two_q_gates
-
-    def threeQ_or_more_gates(self):
-        """Get list of 3-or-more-qubit gates: (id, data)."""
-        warnings.warn(
-            "deprecated function, use dag.multi_qubit_ops(). "
-            "filter output by isinstance(op, Gate) to only get unitary Gates.",
-            DeprecationWarning,
-            stacklevel=2,
-        )
-        three_q_gates = []
-        for node in self.gate_nodes():
-            if len(node.qargs) >= 3:
-                three_q_gates.append(node)
-        return three_q_gates
-
     def two_qubit_ops(self):
         """Get list of 2 qubit operations. Ignore directives like snapshot and barrier."""
         ops = []

qiskit/extensions/quantum_initializer/squ.py

@@ -26,7 +26,6 @@
 from qiskit.circuit.exceptions import CircuitError
 from qiskit.quantum_info.operators.predicates import is_unitary_matrix
 from qiskit.exceptions import QiskitError
-from qiskit.utils.deprecation import deprecate_arguments
 
 _EPS = 1e-10  # global variable used to chop very small numbers to zero
 
@@ -42,9 +41,7 @@ class SingleQubitUnitary(Gate):
                      gate d with u = d.dot(u').
     """
 
-    # pylint: disable=unused-argument
-    @deprecate_arguments({"u": "unitary_matrix"})
-    def __init__(self, unitary_matrix, mode="ZYZ", up_to_diagonal=False, u=None):
+    def __init__(self, unitary_matrix, mode="ZYZ", up_to_diagonal=False):
         """Create a new single qubit gate based on the unitary ``u``."""
         if mode not in ["ZYZ"]:
             raise QiskitError("The decomposition mode is not known.")
@@ -162,9 +159,13 @@ def validate_parameter(self, parameter):
             raise CircuitError(f"invalid param type {type(parameter)} in gate {self.name}")
 
 
-# pylint: disable=unused-argument, invalid-name, missing-type-doc, missing-param-doc
-@deprecate_arguments({"u": "unitary"})
-def squ(self, unitary_matrix, qubit, mode="ZYZ", up_to_diagonal=False, *, u=None):
+def squ(
+    self,
+    unitary_matrix,
+    qubit,
+    mode="ZYZ",
+    up_to_diagonal=False,
+):
     """Decompose an arbitrary 2*2 unitary into three rotation gates.
 
     Note that the decomposition is up to a global phase shift.
@@ -173,13 +174,12 @@ def squ(self, unitary_matrix, qubit, mode="ZYZ", up_to_diagonal=False, *, u=None
 
     Args:
         unitary_matrix (ndarray): 2*2 unitary (given as a (complex) ndarray).
-        qubit (QuantumRegister | Qubit): The qubit which the gate is acting on.
+        qubit (QuantumRegister or Qubit): The qubit which the gate is acting on.
         mode (string): determines the used decomposition by providing the rotation axes.
             The allowed modes are: "ZYZ" (default)
         up_to_diagonal (bool):  if set to True, the single-qubit unitary is decomposed up to
             a diagonal matrix, i.e. a unitary u' is implemented such that there exists a 2*2
             diagonal gate d with u = d.dot(u')
-        u (ndarray): Deprecated, use ``unitary_matrix`` instead.
 
     Returns:
         InstructionSet: The single-qubit unitary instruction attached to the circuit.

qiskit/qasm/node/barrier.py

@@ -12,8 +12,6 @@
 
 """Node for an OPENQASM barrier statement."""
 
-import warnings
-
 from .node import Node
 
 
@@ -27,12 +25,6 @@ def __init__(self, children):
         """Create the barrier node."""
         super().__init__("barrier", children, None)
 
-    def qasm(self, prec=None):
+    def qasm(self):
         """Return the corresponding OPENQASM string."""
-        if prec is not None:
-            warnings.warn(
-                "Parameter 'Barrier.qasm(..., prec)' is no longer used and is being deprecated.",
-                DeprecationWarning,
-                2,
-            )
         return "barrier " + self.children[0].qasm() + ";"

qiskit/qasm/node/binaryop.py

@@ -12,8 +12,6 @@
 
 """Node for an OPENQASM binary operation expression."""
 
-import warnings
-
 from qiskit.exceptions import MissingOptionalLibraryError
 from .node import Node
 
@@ -30,42 +28,14 @@ def __init__(self, children):
         """Create the binaryop node."""
         super().__init__("binop", children, None)
 
-    def qasm(self, prec=None, nested_scope=None):
+    def qasm(self):
         """Return the corresponding OPENQASM string."""
-        if prec is not None:
-            warnings.warn(
-                "Parameter 'BinaryOp.qasm(..., prec)' is no longer "
-                "used and is being deprecated.",
-                DeprecationWarning,
-                2,
-            )
-        if nested_scope is not None:
-            warnings.warn(
-                "Parameter 'BinaryOp.qasm(..., nested_scope)' is no longer "
-                "used and is being deprecated.",
-                DeprecationWarning,
-                2,
-            )
         return (
             "(" + self.children[1].qasm() + self.children[0].value + self.children[2].qasm() + ")"
         )
 
-    def latex(self, prec=None, nested_scope=None):
+    def latex(self):
         """Return the corresponding math mode latex string."""
-        if prec is not None:
-            warnings.warn(
-                "Parameter 'BinaryOp.latex(..., prec)' is no longer used "
-                "and is being deprecated.",
-                DeprecationWarning,
-                2,
-            )
-        if nested_scope is not None:
-            warnings.warn(
-                "Parameter 'BinaryOp.latex(..., nested_scope)' is no longer used "
-                "and is being deprecated.",
-                DeprecationWarning,
-                2,
-            )
         try:
             from pylatexenc.latexencode import utf8tolatex
         except ImportError as ex:
@@ -74,14 +44,8 @@ def latex(self, prec=None, nested_scope=None):
             ) from ex
         return utf8tolatex(self.sym())
 
-    def real(self, nested_scope=None):
+    def real(self):
         """Return the correspond floating point number."""
-        if nested_scope is not None:
-            warnings.warn(
-                "Parameter 'BinaryOp.real(..., nested_scope)' is no longer used and is"
-                " being deprecated.",
-                DeprecationWarning,
-            )
         operation = self.children[0].operation()
         lhs = self.children[1].real()
         rhs = self.children[2].real()

qiskit/qasm/node/binaryoperator.py

@@ -13,7 +13,6 @@
 """Node for an OPENQASM binary operator."""
 
 import operator
-import warnings
 
 from .node import Node
 from .nodeexception import NodeException
@@ -48,13 +47,6 @@ def operation(self):
         except KeyError as ex:
             raise NodeException(f"internal error: undefined operator '{self.value}'") from ex
 
-    def qasm(self, prec=None):
+    def qasm(self):
         """Return the QASM representation."""
-        if prec is not None:
-            warnings.warn(
-                "Parameter 'BinaryOperator.qasm(..., prec)' is no longer used and is "
-                "being deprecated.",
-                DeprecationWarning,
-                2,
-            )
         return self.value

qiskit/qasm/node/cnot.py

@@ -12,8 +12,6 @@
 
 """Node for an OPENQASM CNOT statement."""
 
-import warnings
-
 from .node import Node
 
 
@@ -28,12 +26,6 @@ def __init__(self, children):
         """Create the cnot node."""
         super().__init__("cnot", children, None)
 
-    def qasm(self, prec=None):
+    def qasm(self):
         """Return the corresponding OPENQASM string."""
-        if prec is not None:
-            warnings.warn(
-                "Parameter 'Cnot.qasm(..., prec)' is no longer used and is being deprecated.",
-                DeprecationWarning,
-                2,
-            )
         return "CX " + self.children[0].qasm() + "," + self.children[1].qasm() + ";"

qiskit/qasm/node/creg.py

@@ -11,8 +11,6 @@
 # that they have been altered from the originals.
 
 """Node for an OPENQASM creg statement."""
-import warnings
-
 from .node import Node
 
 
@@ -42,12 +40,6 @@ def to_string(self, indent):
         print(ind, "creg")
         self.children[0].to_string(indent + 3)
 
-    def qasm(self, prec=None):
+    def qasm(self):
         """Return the corresponding OPENQASM string."""
-        if prec is not None:
-            warnings.warn(
-                "Parameter 'Creg.qasm(..., prec)' is no longer used and is being deprecated.",
-                DeprecationWarning,
-                2,
-            )
         return "creg " + self.id.qasm() + ";"

qiskit/qasm/node/customunitary.py

@@ -11,8 +11,6 @@
 # that they have been altered from the originals.
 
 """Node for an OPENQASM custom gate statement."""
-import warnings
-
 from .node import Node
 
 
@@ -42,15 +40,8 @@ def __init__(self, children):
             self.arguments = None
             self.bitlist = children[1]
 
-    def qasm(self, prec=None):
+    def qasm(self):
         """Return the corresponding OPENQASM string."""
-        if prec is not None:
-            warnings.warn(
-                "Parameter 'CustomUnitary.qasm(..., prec)' is no longer used and is "
-                "being deprecated.",
-                DeprecationWarning,
-                2,
-            )
         string = self.name
         if self.arguments is not None:
             string += "(" + self.arguments.qasm() + ")"

qiskit/qasm/node/expressionlist.py

@@ -11,8 +11,6 @@
 # that they have been altered from the originals.
 
 """Node for an OPENQASM expression list."""
-import warnings
-
 from .node import Node
 
 
@@ -30,13 +28,6 @@ def size(self):
         """Return the number of expressions."""
         return len(self.children)
 
-    def qasm(self, prec=None):
+    def qasm(self):
         """Return the corresponding OPENQASM string."""
-        if prec is not None:
-            warnings.warn(
-                "Parameter 'ExpressionList.qasm(..., prec)' is no longer used and is "
-                "being deprecated.",
-                DeprecationWarning,
-                2,
-            )
         return ",".join([self.children[j].qasm() for j in range(self.size())])