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lib.data: add a diagnostic for slicing data.View.

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This is meaningless for a view but meaningful for the underlying value.

Fixes #1375.
This commit is contained in:
Catherine 2024-06-10 13:28:43 +01:00
parent 0140fe27e2
commit c649045f35
2 changed files with 9 additions and 0 deletions
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3
amaranth/lib/data.py
View file

@ -792,6 +792,9 @@ class View(ValueCastable):
:exc:`TypeError` :exc:`TypeError`
If :meth:`.ShapeCastable.__call__` does not return a value or a value-castable object. If :meth:`.ShapeCastable.__call__` does not return a value or a value-castable object.
""" """
if isinstance(key, slice):
raise TypeError(
"View cannot be indexed with a slice; did you mean to call `.as_value()` first?")
if isinstance(self.__layout, ArrayLayout): if isinstance(self.__layout, ArrayLayout):
if not isinstance(key, (int, Value, ValueCastable)): if not isinstance(key, (int, Value, ValueCastable)):
raise TypeError( raise TypeError(

6
tests/test_lib_data.py
View file

@ -670,6 +670,12 @@ class ViewTestCase(FHDLTestCase):
r"with a value$"): r"with a value$"):
Signal(data.StructLayout({}))[Signal(1)] Signal(data.StructLayout({}))[Signal(1)]
def test_index_wrong_slice(self):
with self.assertRaisesRegex(TypeError,
r"^View cannot be indexed with a slice; did you mean to call `.as_value\(\)` "
r"first\?$"):
Signal(data.StructLayout({}))[0:1]
def test_getattr(self): def test_getattr(self):
v = Signal(data.UnionLayout({ v = Signal(data.UnionLayout({
"a": unsigned(2), "a": unsigned(2),