Bug Report

If a dict literal contains a value of type Optional[Any], other optional values (e.g. Optional[T1], Optional[T2]), and non optional (non-overlapping) values (e.g. T3, T4), then its inferred type is dict[KeyType*, Union[T1, None, T2]] ignoring Any, T3, and T4.

To Reproduce

from datetime import datetime
from decimal import Decimal
from typing import Any, Optional

optional_any: Optional[Any]
optional_string: Optional[str]
optional_int: Optional[int]
my_dict = {
    "datetime": datetime(2020, 1, 1),
    "Decimal": Decimal("2000"),
    "optional_any": optional_any,
    "optional_str": optional_string,
    "optional_int": optional_int,
}
reveal_type(my_dict)

Output from mypy is:

scratchfile.py:9: error: Dict entry 0 has incompatible type "str": "datetime"; expected "str": "Union[str, None, int]"  [dict-item]
scratchfile.py:10: error: Dict entry 1 has incompatible type "str": "Decimal"; expected "str": "Union[str, None, int]"  [dict-item]
scratchfile.py:15: note: Revealed type is 'builtins.dict[builtins.str*, Union[builtins.str, None, builtins.int]]'

Expected Behavior

I would've expected the inferred type of my_dict to be dict[str*, Union[Any, str, None, int, Decimal, datetime]]
Or just reduce to dict[str*, object*]

Your Environment

• Mypy version used: 0.782
• Mypy command-line flags: --show-error-codes
• Python version used: Tested on 3.6.9 and 3.7.3
• Operating system and version: macOS Catalina Version 10.15.6

I can work around this quite easily (by either type: ignore, or cast on the Any) But thought I'd raise it in case this isn't expected behaviour.