QUERY · ISSUE

Type Inference issue when using struct in viper

openby GuillaumeLeclercopened 2023-05-28updated 2023-05-28

bug

MY_TYPE = {
    "var": 0 | uctypes.UINT32
}
storage = bytearray(uctypes.sizeof(MY_TYPE))

@micropython.viper
def bugreport():
    data = uctypes.struct(ptr32(storage), MY_TYPE)
    data.var += int(1)

bugreport()

For some reason data.var is an object even though it's type is clearly defined from the struct. the following error occurs:

ViperTypeError: can\'t do binary op between \'object\' and \'int\'

CANDIDATE · ISSUE

viper: ViperTypeError: can't do binary op between 'uint' and 'uint'

closedby peterhinchopened 2016-02-15updated 2020-06-26

The following produces the above error at compile time (only with uints - compiles and runs with int)

@micropython.viper
def foo(arg1: uint, arg2: uint) -> uint:
    return arg1 + arg2

MicroPython v1.6-35-ge372e83 on 2016-02-11; PYBv1.0 with STM32F405RG

Assessment

Q Qwen · high

Both issues involve ViperTypeError related to binary operations in MicroPython's Viper compiler. However, they address different root causes: Issue #11638 is about type inference failure for struct fields accessed via uctypes.struct (treating them as objects instead of their declared type), while Issue #1847 is about the Viper compiler incorrectly rejecting binary operations between two uint-typed arguments. The error messages are similar but the underlying problems are distinct - one is about type inference for struct fields, the other is about type checking for uint operations. They share the Viper component but don't resolve each other.

Suggested action

Keep both issues open as they address different bugs in the Viper type system. The issues may be related in that they both involve Viper's type checking, but they require separate fixes.

Type Inference issue when using struct in viper

viper: ViperTypeError: can't do binary op between 'uint' and 'uint'

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