[python, run] Creating data classes with constructors generates empty return

[annagrin]

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Describe the bug

Creating data classes with constructors generates empty return

Steps to reproduce the bug

@dataclass
class MyClass:
    def __init__(self, i):
        self.x = i

@cudaq.kernel
def bugSP2() -> MyClass:
    return MyClass(-13)

print(cudaq.run(bugSP2, shots_count = 2))

Output:
[]

Expected behavior

Error if an __init__ is defined in a data class.

Is this a regression? If it is, put the last known working version (or commit) here.

Not a regression

Environment

• CUDA-Q version:
• Python version:
• C++ compiler:
• Operating system:

Suggestions

No response

[sacpis]

For now, (as per @boschmitt's suggestion), we can use frozen=True on a dataclass.

import cudaq
import dataclasses

@dataclasses.dataclass(frozen=True)
class MyClass:
    x:int
    y:int
    
@cudaq.kernel
def bugSP2() -> MyClass:
    return MyClass(6, 7)

print(cudaq.run(bugSP2, shots_count = 2))

If we try to assign any value to existing attributes using a customized constructor (__init__ method), it throws the following error

dataclasses.FrozenInstanceError: cannot assign to field 'x'

[sacpis]

This will be fixed with @bettinaheim's latest PR #3537.