fix: use from __future__ import annotations with TYPE_CHECKING guard

Add from __future__ import annotations to all 12 files so that
type hints are treated as strings at runtime (fixing Python 3.10
NameError). Keep TYPE_CHECKING guard for DAGCircuit import to
satisfy ruff F821. This matches the pattern used in basepasses.py
and layout.py.

Also fixes contains_instruction.py module docstring (was copy-paste
from fixed_point.py).

Author: Hadar01

qiskit/transpiler/passes/analysis/count_ops.py

@@ -12,6 +12,8 @@
 
 """Count the operations in a DAG circuit."""
 
+from __future__ import annotations
+
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:

qiskit/transpiler/passes/analysis/count_ops_longest_path.py

@@ -12,6 +12,8 @@
 
 """Count the operations on the longest path in a DAGCircuit."""
 
+from __future__ import annotations
+
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:

qiskit/transpiler/passes/analysis/dag_longest_path.py

@@ -12,6 +12,8 @@
 
 """Return the longest path in a :class:`.DAGCircuit` as a list of DAGNodes."""
 
+from __future__ import annotations
+
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:

qiskit/transpiler/passes/analysis/depth.py

@@ -12,6 +12,8 @@
 
 """Calculate the depth of a DAG circuit."""
 
+from __future__ import annotations
+
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:

qiskit/transpiler/passes/analysis/num_qubits.py

@@ -12,6 +12,8 @@
 
 """Calculate the number of qubits of a DAG circuit."""
 
+from __future__ import annotations
+
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:

qiskit/transpiler/passes/analysis/num_tensor_factors.py

@@ -12,10 +12,13 @@
 
 """Calculate the number of tensor factors of a DAG circuit."""
 
+from __future__ import annotations
+
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
     from qiskit.dagcircuit import DAGCircuit
+
 from qiskit.transpiler.basepasses import AnalysisPass
 
 

qiskit/transpiler/passes/analysis/resource_estimation.py

@@ -12,6 +12,8 @@
 
 """Automatically require analysis passes for resource estimation."""
 
+from __future__ import annotations
+
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:

qiskit/transpiler/passes/analysis/size.py

@@ -12,6 +12,8 @@
 
 """Calculate the size of a DAG circuit."""
 
+from __future__ import annotations
+
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:

qiskit/transpiler/passes/analysis/width.py

@@ -12,6 +12,8 @@
 
 """Calculate the width of a DAG circuit."""
 
+from __future__ import annotations
+
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:

qiskit/transpiler/passes/utils/contains_instruction.py

@@ -10,7 +10,9 @@
 # copyright notice, and modified files need to carry a notice indicating
 # that they have been altered from the originals.
 
-"""Check if a property reached a fixed point."""
+"""Check if the DAG contains a specific instruction."""
+
+from __future__ import annotations
 
 from collections.abc import Iterable
 from typing import TYPE_CHECKING