docs: change combinatorial to combinational

- Replace occurrences of combinatorial with combinational in docstrings
- Replace occurrences of combinatorial with combinational in .rst files
- Add note to contrib.rst to document the editorial decision from #1301

amaranth/hdl/_ast.py

@@ -1986,14 +1986,14 @@ class Signal(Value, DUID, metaclass=_SignalMeta):
         name this ``Signal`` is assigned to. If the empty string, then this ``Signal`` is treated
         as private and is generally hidden from view.
     init : int or integral Enum
-        Reset (synchronous) or default (combinatorial) value.
+        Reset (synchronous) or default (combinational) value.
         When this ``Signal`` is assigned to in synchronous context and the corresponding clock
         domain is reset, the ``Signal`` assumes the given value. When this ``Signal`` is unassigned
-        in combinatorial context (due to conditional assignments not being taken), the ``Signal``
+        in combinational context (due to conditional assignments not being taken), the ``Signal``
         assumes its ``init`` value. Defaults to 0.
     reset_less : bool
         If ``True``, do not generate reset logic for this ``Signal`` in synchronous statements.
-        The ``init`` value is only used as a combinatorial default or as the initial value.
+        The ``init`` value is only used as a combinational default or as the initial value.
         Defaults to ``False``.
     attrs : dict
         Dictionary of synthesis attributes.

amaranth/hdl/_cd.py

@@ -35,7 +35,7 @@ class ClockDomain:
     ----------
     clk : Signal, inout
         The clock for this domain. Can be driven or used to drive other signals (preferably
-        in combinatorial context).
+        in combinational context).
     rst : Signal or None, inout
         Reset signal for this domain. Can be driven or used to drive.
     """

amaranth/hdl/_nir.py

@@ -768,7 +768,7 @@ class Part(Cell):
 
 
 class Matches(Cell):
-    """A combinatorial cell performing a comparison like ``Value.matches``
+    """A combinational cell performing a comparison like ``Value.matches``
     (or, equivalently, a case condition).
 
     Attributes

amaranth/lib/io.py

@@ -296,7 +296,7 @@ class DifferentialPort(PortLike):
 
 
 class Buffer(wiring.Component):
-    """A combinatorial I/O buffer.
+    """A combinational I/O buffer.
 
     Parameters
     ----------
@@ -309,7 +309,7 @@ class Buffer(wiring.Component):
         Created based on constructor arguments.
     """
     class Signature(wiring.Signature):
-        """A signature of a combinatorial I/O buffer.
+        """A signature of a combinational I/O buffer.
 
         Parameters
         ----------
@@ -665,7 +665,7 @@ class Pin(wiring.PureInterface):
         If ``"io"`` is specified, both the ``i``/``iN`` and ``o``/``oN`` signals are present, and
         an ``oe`` signal is present.
     xdr : int
-        Gearbox ratio. If equal to 0, the I/O buffer is combinatorial, and only ``i``/``o``
+        Gearbox ratio. If equal to 0, the I/O buffer is combinational, and only ``i``/``o``
         signals are present. If equal to 1, the I/O buffer is SDR, and only ``i``/``o`` signals are
         present. If greater than 1, the I/O buffer includes a gearbox, and ``iN``/``oN`` signals
         are present instead, where ``N in range(0, N)``. For example, if ``xdr=2``, the I/O buffer

amaranth/sim/core.py

@@ -183,7 +183,7 @@ class Simulator:
         """Advance the simulation.
 
         Run every process and commit changes until a fixed point is reached, then advance time
-        to the closest deadline (if any). If there is an unstable combinatorial loop,
+        to the closest deadline (if any). If there is an unstable combinational loop,
         this function will never return.
 
         Returns ``True`` if there are any active processes, ``False`` otherwise.