Pyright

New Feature: Added type checking for generator functions (i.e. functions that contain a 'yield' or 'yield from' statement).
New Feature: Added type checking for coroutine functions (i.e. async functions).
New Feature: Added type checking enforcement for iterators used in 'for' statements (__iter__ or __aiter__ overrides).
New Feature: Added type checking enforcement for 'with' statement (__enter__ or __aenter__ overrides).
New Feature: Added support for NoReturn return type.
New Feature: Replaced "--timing" command-line with "--stats", which now provides more stats than just timing.
Fixed bug where the use of a module as a type argument was not flagged as an error.
Improved type specialization logic for member accesses.

New Feature: Type checker now supports generators functions. If yield type isn't specified, the checker infers the type from yield clauses.
New Feature: Added support for type hints that use a combination of string and non-string tokens (e.g. Optional['Foo']).
New Feature: Added support for comment-based type hints for assignment statements, since these are used in some typeshed stub files.
New Feature: Added support for class decorators and added a configuration switch "reportUntypedClassDecorator" to allow these to be flagged by the type checker.
New Feature: Type checker now distinguishes between access, set, and delete operations when accessing members of an object and flags errors when that usage is not supported (e.g. writing to a property that has no defined setter).
Enhancement: Improved type checker's ability to track types within while and for loops.
Fixed bug with structural (protocol) type checking that generated false positives.
Deleted Python 2 typeshed fallback stub files since they are never used by Pyright. This reduced the package size by about 100K.

New Feature: Type checking support for dataclass, which was introduced in Python 3.7.
New Feature: Type checker now reports incorrect usage of ellipses in various cases.
Fixed 67: Modules are now treated as though they derive from object by the type checker.
Improved responsiveness of VS Code extension.
Improved error reporting for abstract class instantiation; abstract methods are now reported with their containing class.
Fixed 68: Silenced incorrect error for star expression usage (list expansion).
Fixed some edge cases relating to __new__ and __init__ validation.
Fixed 66: Bug caused an infinite loop in type checker.
Fixed automatic detection of python import paths for Python 3.x environments (contribution from zhangkaizhao)

New Feature: Partial support for Python 3.7 data classes. Classes must subclass from `NamedTuple`. Doesn't yet handle `dataclass` class decorator. (Contribution from mhzed)
New Feature: Detect and flag attempt to instantiate abstract class or any class that derives from an abstract class that doesn't override all abstract methods.
New Feature: Pyright now retrieves the search paths from the default python interpreter or from the interpreter specified by the `python.pythonPath` setting in VS Code.
Fixed bug in file URI formatting that caused error messages on Windows.
Fixed exit code reporting in command-line tool.
Provided hover support in VS Code extension for symbols that have unknown types.

New Feature: Type analyzer now analyzes function decorators rather than ignoring type analysis for all calls to functions that have decorators. Proper analysis requires decorators to be annotated appropriately. A new config switch "reportUntypedFunctionDecorator" to identify decorators that lack the appropriate type annotations and therefore defeat type checking.
New Feature: Type analyzer is now smarter about analyzing while/else statements.
New Feature: Type analyzer handles `while True` and knows that it will not exit through the bottom of the loop.
New Feature: Pyright VS Code extension is now activated automatically if a pyrightconfig.json file is present in the workspace.
New Feature: Type analyzer now specializes the parameter and return types when analyzing a method on a specialized class.
New Feature: Type analyzer now takes into account parameters to the constructor (including the __init__ method) to infer the specialized type of an object.
New Feature: Variable ${workspaceFolder} is now expanded for paths that come from VS Code settings (like "python.venvPath").
New Feature: "Naked" raise is now flagged as an error if used outside of except clause.
New Feature: Added "--timing" switch to command-line tool to output detailed timing stats. By default, only the total time is reported.
New Feature: Command-line version can now be run with no parameters. It looks in the current working directory for a configuration file called "pyrightconfig.json".
Fixed exit code reporting in command-line version. It now properly exits with a code of zero if no errors or warnings are found.
Fixed bugs related to relative imports, especially with relative imports that consist of only "." or "..".
Fixed several bugs in type analysis engine related to tuples.
Removed "-P" switch from command-line tool. It was deprecated in the previous release.

New Feature: Added new configuration switches reportOptionalSubscript, reportOptionalMemberAccess and reportOptionalCall to control whether the type checker should report errors for these conditions.
New Feature: Added type analysis for lambdas.
New Feature: Added more comprehensive error reporting for type mismatch errors. These multi-line errors now include hierarchical information and detail about the detected type mismatch, allowing for easier diagnosis.
New Feature: The type checker now reports cases where a non-quoted type forward reference is used within a regular ".py" file. Such forward references are allowed in stub files.
Fixed several bugs in type matching logic related to function (Callable) types.
Fixed bug in handling of special-case types like Dict and FrozenSet when they are used in type annotations with no type arguments.
Added missing support for matrix multiply operator (``).