lib.io: use keyword-only arguments in Pin().

nmigen/build/res.py

@@ -134,7 +134,7 @@ class ResourceManager:
                 if dir == "-":
                     pin = None
                 else:
-                    pin = Pin(len(phys), dir, xdr, name=name)
+                    pin = Pin(len(phys), dir, xdr=xdr, name=name)
 
                 for phys_name in phys_names:
                     if phys_name in self._phys_reqd:

nmigen/lib/io.py

@@ -97,7 +97,7 @@ class Pin(Record):
         cannot change direction more than once per cycle, so at most one output enable signal
         is present.
     """
-    def __init__(self, width, dir, xdr=0, name=None, src_loc_at=0):
+    def __init__(self, width, dir, *, xdr=0, name=None, src_loc_at=0):
         self.width = width
         self.dir   = dir
         self.xdr   = xdr