hdl.ast: clarify exception message for out of bounds indexing.

Fixes #488.
2020-08-27 01:14:05 +00:00 · 2020-08-27 01:14:05 +00:00 · fde242aa47
commit fde242aa47
parent 5b01499901
2 changed files with 2 additions and 2 deletions
--- a/nmigen/hdl/ast.py
+++ b/nmigen/hdl/ast.py
@ -254,7 +254,7 @@ class Value(metaclass=ABCMeta):
        n = len(self)
        if isinstance(key, int):
            if key not in range(-n, n):
-                raise IndexError("Cannot index {} bits into {}-bit value".format(key, n))
+                raise IndexError(f"Index {key} is out of bounds for a {n}-bit value")
            if key < 0:
                key += n
            return Slice(self, key, key + 1)