This is actually an existing correctness requirement (for the similar
reasons that ValueCastable.as_value() must always return the same
value every time) that for some reason wasn't respected.
See amaranth-lang/rfcs#15 and #784.
Note that this RFC breaks the existing syntax for initializing a view
with a new signal. Instances of `View(layout)` *must* be changed to
`Signal(layout)`.
See amaranth-lang/rfcs#15 and #784.
Note that this RFC breaks the existing syntax for initializing a view
with a new signal. Instances of `View(layout)` *must* be changed to
`Signal(layout)`.
Found while working on amaranth/rfcs#15. The new code is also robust
in the face of RFC 15 itself (the value returned by Signal will change
but that will save work for the programmer).
The __init_subclass__ method fires on class definition rather than use.
It also has the bonus impact that no __new__ method is defined, so the
classes can be correctly detected as mix-in classes by modules such as
enum.
In some cases, a toolchain might produce shell output that isn't correct
UTF-8. To avoid crashing in such cases, pass errors="replace" to
bytes.decode.
For example, Lattice Diamond uses the Latin-1 encoding for some reason.
This recently broke my setup because the month turned to "März" in a
German locale:
--- Start Time: Fr. M�r 3 20:01:41 2023
See amaranth-lang/rfcs#4.
This functionality was not explicitly specified in the RFC but it
falls under "anywhere an integer or an enumeration is accepted".
* Reject union initialization with more than one reset value.
* Replace the reset value specified in the class definition with
the one provided during initalization instead of merging.
* Annotations like `s: unsigned(4) = 1` are recognized and
the assigned value is used as the reset value for the implicitly
created `Signal`.
* Base classes inheriting from `Struct` and `Union` without
specifying a layout are recognized.
* Classes that both inherit from a base class with a layout and
specify a layout are rejected.
Mutability of Field isn't specified by the RFC and can cause issues
if the objects stored in Layout subclasses are mutated. There isn't
any reason to do that (the subclasses themselves are mutable and
handle that correctly), so disallow it.
