clean up Cat and Repl after realising that Value.cast will pass through

something that is already derived from Value (UserValue) unmodified

diff --git a/nmigen/hdl/ast.py b/nmigen/hdl/ast.py
index 03d2be6ea56ebcdd429fa4fb53a391dee2517234..39fb33f4d7bd36b33936c5e9f3f962aed7532150 100644 (file)
--- a/nmigen/hdl/ast.py
+++ b/nmigen/hdl/ast.py
@@ -862,18 +862,13 @@ def Cat(*args, src_loc_at=0):
     lose the opportunity for "redirection" (Value.__Cat__ would
     always be called).
     """
-    # flatten the args and convert to tuple (not a generator)
-    args = tuple(flatten(args))
+    # rely on Value.cast leaving Value/UserValue unmodified
+    args = [Value.cast(v) for v in flatten(args)]
     # check if there are no arguments (zero-length Signal).
     if len(args) == 0:
         return _InternalCat(*args, src_loc_at=src_loc_at)
-    # determine if the first is a UserValue.
-    first, rest = args[0], args[1:]
-    if not isinstance(args[0], UserValue):
-        first = Value.cast(first) # ok to downcast to Value
-    # all other arguments are safe to downcast to Value
-    rest = map(Value.cast, rest)
     # assume first item defines the "handling" for all others
+    first, rest = args[0], args[1:]
     return first.__Cat__(*rest, src_loc_at=src_loc_at)
 
 
@@ -927,8 +922,7 @@ class _InternalCat(Value):
 
 @final
 def Repl(value, count, *, src_loc_at=0):
-    if not isinstance(value, Value): # rare instances where integers are passed
-        value = Value.cast(value)
+    value = Value.cast(value) # relies on Value/UserValue returned unmodified
     return value.__Repl__(count, src_loc_at=src_loc_at)