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lib.enum: fix shape calculation for const-castable member values.

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This commit is contained in:
Catherine 2023-02-28 13:30:26 +00:00
parent de36e3c162
commit 7ea2e175e4
1 changed files with 5 additions and 5 deletions
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10
amaranth/lib/enum.py
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@ -2,7 +2,6 @@ import enum as py_enum
import warnings import warnings
from ..hdl.ast import Shape, ShapeCastable, Const from ..hdl.ast import Shape, ShapeCastable, Const
from .._utils import bits_for
__all__ = py_enum.__all__ __all__ = py_enum.__all__
@ -38,20 +37,21 @@ class EnumMeta(ShapeCastable, py_enum.EnumMeta):
cls._amaranth_shape_ = shape = Shape.cast(shape) cls._amaranth_shape_ = shape = Shape.cast(shape)
for member in cls: for member in cls:
try: try:
Const.cast(member.value) member_shape = Const.cast(member.value).shape()
except TypeError as e: except TypeError as e:
raise TypeError("Value of enumeration member {!r} must be " raise TypeError("Value of enumeration member {!r} must be "
"a constant-castable expression" "a constant-castable expression"
.format(member)) from e .format(member)) from e
width = bits_for(member.value, shape.signed) if member_shape.signed and not shape.signed:
if member.value < 0 and not shape.signed:
warnings.warn( warnings.warn(
message="Value of enumeration member {!r} is signed, but enumeration " message="Value of enumeration member {!r} is signed, but enumeration "
"shape is {!r}" # the repr will be `unsigned(X)` "shape is {!r}" # the repr will be `unsigned(X)`
.format(member, shape), .format(member, shape),
category=RuntimeWarning, category=RuntimeWarning,
stacklevel=2) stacklevel=2)
elif width > shape.width: elif (member_shape.width > shape.width or
member_shape.width == shape.width and
shape.signed and not member_shape.signed):
warnings.warn( warnings.warn(
message="Value of enumeration member {!r} will be truncated to " message="Value of enumeration member {!r} will be truncated to "
"enumeration shape {!r}" "enumeration shape {!r}"