Improved handling of types float and complex, which are special-c…

[erictraut]

…ased in PEP 484 as "promotion types". The new logic now properly models the runtime behavior for isinstance and class pattern matching when used with these promotion types. This addresses #6008.

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

AutoSplit (https://github.com/Toufool/AutoSplit)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplit.py:806:17 - error: Type of "pause_times" is partially unknown
+     Type of "pause_times" is "list[AutoSplit | float | Unknown]" (reportUnknownVariableType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplit.py:308:9 - error: Type of "start_image_threshold" is partially unknown
+     Type of "start_image_threshold" is "AutoSplit | float | Unknown" (reportUnknownVariableType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplit.py:317:66 - error: Argument type is partially unknown
+     Argument corresponds to parameter "value" in function "decimal"
+     Argument type is "AutoSplit | float | Unknown" (reportUnknownArgumentType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplit.py:325:9 - error: Type of "similarity_diff" is partially unknown
+     Type of "similarity_diff" is "float | Unknown" (reportUnknownVariableType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplit.py:551:31 - error: Argument type is partially unknown
+     Argument corresponds to parameter "stop_time" in function "__pause_loop"
+     Argument type is "AutoSplit | float | Unknown" (reportUnknownArgumentType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplit.py:619:34 - error: Argument type is partially unknown
+     Argument corresponds to parameter "stop_time" in function "__pause_loop"
+     Argument type is "AutoSplit | float | Unknown" (reportUnknownArgumentType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplit.py:804:17 - error: Type of "threshold" is partially unknown
+     Type of "threshold" is "AutoSplit | float | Unknown" (reportUnknownVariableType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplit.py:809:62 - error: Argument type is partially unknown
+     Argument corresponds to parameter "__iterable" in function "max"
+     Argument type is "list[AutoSplit | float | Unknown]" (reportUnknownArgumentType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplit.py:809:17 - error: Type of "paused" is partially unknown
+     Type of "paused" is "bool | Unknown" (reportUnknownVariableType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplit.py:814:21 - error: Type of "should_reset" is partially unknown
+     Type of "should_reset" is "bool | Unknown" (reportUnknownVariableType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplit.py:820:72 - error: Argument type is partially unknown
+     Argument corresponds to parameter "value" in function "decimal"
+     Argument type is "AutoSplit | float | Unknown" (reportUnknownArgumentType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplit.py:851:66 - error: Argument type is partially unknown
+     Argument corresponds to parameter "value" in function "decimal"
+     Argument type is "AutoSplit | float | Unknown" (reportUnknownArgumentType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplitImage.py:78:26 - error: Cannot access member "settings_dict" for type "int"
+     Member "settings_dict" is unknown (reportGeneralTypeIssues)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplitImage.py:76:9 - error: Type of "default_value" is partially unknown
+     Type of "default_value" is "AutoSplit | float | Unknown" (reportUnknownVariableType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplitImage.py:71:26 - error: Cannot access member "settings_dict" for type "int"
+     Member "settings_dict" is unknown (reportGeneralTypeIssues)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplitImage.py:69:9 - error: Type of "default_value" is partially unknown
+     Type of "default_value" is "AutoSplit | float | Unknown" (reportUnknownVariableType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplitImage.py:72:16 - error: Return type, "AutoSplit | float | Unknown", is partially unknown (reportUnknownVariableType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplitImage.py:67:9 - error: Return type, "AutoSplit | float | Unknown", is partially unknown (reportUnknownParameterType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplitImage.py:79:16 - error: Return type, "AutoSplit | float | Unknown", is partially unknown (reportUnknownVariableType)
+   /tmp/mypy_primer/projects/AutoSplit/src/AutoSplitImage.py:74:9 - error: Return type, "AutoSplit | float | Unknown", is partially unknown (reportUnknownParameterType)
+   /tmp/mypy_primer/projects/AutoSplit/src/menu_bar.py:181:21 - error: Argument type is partially unknown
+     Argument corresponds to parameter "value" in function "decimal"
+     Argument type is "AutoSplit | float | Unknown" (reportUnknownArgumentType)
+   /tmp/mypy_primer/projects/AutoSplit/src/menu_bar.py:186:21 - error: Argument type is partially unknown
+     Argument corresponds to parameter "value" in function "decimal"
+     Argument type is "AutoSplit | float | Unknown" (reportUnknownArgumentType)
- 486 errors, 30 warnings, 7 informations 
+ 508 errors, 30 warnings, 7 informations 

[Avasam]

@erictraut Is that mypy_primer result expected? If so, why does a isinstance condition results in an unknown type in the else branch for floats unions?

[erictraut]

Yes, this is expected.

This code sample should make it clear why

def func(x: float | str):
    if isinstance(x, float):
        print('received a float!')
    else:
        reveal_type(x) # int | str

        # The following line is a type violation because `x` is
        # is possibly an `int`.
        return x.upper()

func(1)