Struct __post_init__ is not called when converting to Struct with from_attributes=True

[NCRonB]

Description

When using msgspec.convert() to convert to a Struct with from_attributes=True, the Struct's __post_init__ is not called. It works as expected with dataclasses.

from dataclasses import dataclass
import msgspec

@dataclass
class DataclassEgg:
	grade: str
	
	def __post_init__(self):
		self.grade = f"dataclass({self.grade})"

class StructEgg(msgspec.Struct):
	grade: str

	def __post_init__(self):
		self.grade = f"Struct({self.grade})"

>>> egg = {"grade": "A"}

>>> struct_egg = msgspec.convert(egg, StructEgg)
>>> struct_egg
StructEgg(grade='Struct(A)')

>>> dataclass_egg = msgspec.convert(egg, DataclassEgg)
>>> dataclass_egg
DataclassEgg(grade='dataclass(A)')

>>> msgspec.convert(struct_egg, DataclassEgg, from_attributes=True)  # DataclassEgg post init is called
DataclassEgg(grade='dataclass(Struct(A))')

>>> msgspec.convert(dataclass_egg, StructEgg, from_attributes=True)  # StructEgg post init is not called
StructEgg(grade='dataclass(A)')

The last one should be:

StructEgg(grade='Struct(dataclass(A))')

[jankotuc-photoneo]

affects me as well