Make BufferedWriter generic over a protocol

[srittau]

[srittau]

Closes: #13495.

[github-actions[bot]]

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

ibis (https://github.com/ibis-project/ibis)
- ibis/expr/visualize.py:182: error: Incompatible types in assignment (expression has type "BufferedWriter", variable has type "_TemporaryFileWrapper[bytes]")  [assignment]
+ ibis/expr/visualize.py:182: error: Incompatible types in assignment (expression has type "BufferedWriter[_BufferedWriterStream]", variable has type "_TemporaryFileWrapper[bytes]")  [assignment]

urllib3 (https://github.com/urllib3/urllib3)
+ src/urllib3/util/ssltransport.py:156: error: Value of type variable "_BufferedWriterStreamT" of "BufferedRWPair" cannot be "SocketIO"  [type-var]
+ src/urllib3/util/ssltransport.py:156: note: Error code "type-var" not covered by "type: ignore" comment
+ src/urllib3/util/ssltransport.py:161: error: Value of type variable "_BufferedWriterStreamT" of "BufferedWriter" cannot be "SocketIO"  [type-var]

[github-actions[bot]]

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

ibis (https://github.com/ibis-project/ibis)
- ibis/expr/visualize.py:182: error: Incompatible types in assignment (expression has type "BufferedWriter", variable has type "_TemporaryFileWrapper[bytes]")  [assignment]
+ ibis/expr/visualize.py:182: error: Incompatible types in assignment (expression has type "BufferedWriter[_BufferedWriterStream]", variable has type "_TemporaryFileWrapper[bytes]")  [assignment]

[github-actions[bot]]

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

ibis (https://github.com/ibis-project/ibis)
- ibis/expr/visualize.py:182: error: Incompatible types in assignment (expression has type "BufferedWriter", variable has type "_TemporaryFileWrapper[bytes]")  [assignment]
+ ibis/expr/visualize.py:182: error: Incompatible types in assignment (expression has type "BufferedWriter[_BufferedWriterStream]", variable has type "_TemporaryFileWrapper[bytes]")  [assignment]

[github-actions[bot]]

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

zope.interface (https://github.com/zopefoundation/zope.interface)
- src/zope/interface/common/tests/test_io.py:36: error: Argument 1 to "BufferedWriter" has incompatible type "StringIO"; expected "RawIOBase"  [arg-type]
+ src/zope/interface/common/tests/test_io.py:36: error: Value of type variable "_BufferedWriterStreamT" of "BufferedWriter" cannot be "StringIO"  [type-var]
- src/zope/interface/common/tests/test_io.py:41: error: Argument 2 to "BufferedRWPair" has incompatible type "BytesIO"; expected "RawIOBase"  [arg-type]

ibis (https://github.com/ibis-project/ibis)
- ibis/expr/visualize.py:182: error: Incompatible types in assignment (expression has type "BufferedWriter", variable has type "_TemporaryFileWrapper[bytes]")  [assignment]
+ ibis/expr/visualize.py:182: error: Incompatible types in assignment (expression has type "BufferedWriter[_BufferedWriterStream]", variable has type "_TemporaryFileWrapper[bytes]")  [assignment]

[github-actions[bot]]

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

zope.interface (https://github.com/zopefoundation/zope.interface)
- src/zope/interface/common/tests/test_io.py:36: error: Argument 1 to "BufferedWriter" has incompatible type "StringIO"; expected "RawIOBase"  [arg-type]
+ src/zope/interface/common/tests/test_io.py:36: error: Value of type variable "_BufferedWriterStreamT" of "BufferedWriter" cannot be "StringIO"  [type-var]
- src/zope/interface/common/tests/test_io.py:41: error: Argument 2 to "BufferedRWPair" has incompatible type "BytesIO"; expected "RawIOBase"  [arg-type]

ibis (https://github.com/ibis-project/ibis)
- ibis/expr/visualize.py:182: error: Incompatible types in assignment (expression has type "BufferedWriter", variable has type "_TemporaryFileWrapper[bytes]")  [assignment]
+ ibis/expr/visualize.py:182: error: Incompatible types in assignment (expression has type "BufferedWriter[_BufferedWriterStream]", variable has type "_TemporaryFileWrapper[bytes]")  [assignment]