This is bigger update since all of these changes are done on the same parts of code and they are dependent on each other, so it's hard to separate them to individual PRs.

Don't be overwhelmed by long change list (I'm a bit pedantic), many points are the result of one fix/change, but code changes are rather straight forward.

Description of the Change

added

• mixed type (PHP 8.0)
• static type in method's return (PHP 8.0)
• added union types (PHP 8.0)
• meta.function.parameter.variadic.php since this is unique parameter without default value, token could be more useful than removed array variant
• constructor property promotion (PHP 8.0)

fixed

• variadic parameter handling e.g. no default value allowed
• multiple $ in a parameters (only one is allowed)
• classes in type hints are now properly tokenized support.class.php instead of storage.type.php. Fixes Inconsistent primitive typehint tokenization #387, PHP class and primitive type function parameters scoped and highlighted identically microsoft/vscode#95029
• use inheritance in closures: added comma token and meta.function.closure.use.php widened to whole use statement
• constructor no longer allows return type declaration

changed

• type hints are now single separate rule
• for consistency, boundary spaces are not a part of the parameter nor the variable token

removed

• meta.function.parameter.array.php and invalid.illegal.non-null-typehinted.php - problematic with union types (since 8.0), broken by constant expressions in default value (since 5.6) and logic errors should be checked by intellisense anyway. Also fixes Default array value syntax error with class constants #363 and Coloring/Highlighting Issues for Exceptions and Constants in PHP #390 2nd point
• storage.type.php for namespace name in namespaced class reference - probably added by mistake in 2 places (one by me, sorry)

test spec

• trailing comma (already supported; PHP 8.0)
  • use namespace
  • function parameters
  • closure parameters, use inheritance
• basic method (missing tests)
• union types (with false)
• mixed type
• static return type in methods
• constructor property promotion
• constructor illegal return type declaration

Alternate Designs

• We may want to add meta.function.parameter.type.php and meta.function.return.type.php (type/typehint) for whole type hint (union, nullable). Could be useful, but feedback is needed.
• parent, self, static probably should be changed from storage.type.php to support.class.parent.php or keyword.other.parent.php or something like this.
• Methods are tokenized as meta.function.php, maybe this should be changed to meta.function.method.php or meta.method.php
• parameter-default-types can be changed to $self, but more tests are needed.

Possible Drawbacks

This update will break PR #389, but at the same time fixes original problem making mentioned PR not needed anymore.

There may be some coloring changes, but all should be improvements, rather than degradation.

Applicable Issues

PHP 8.0 update log: #395

fix #363 fix #387 fix microsoft/vscode#95029
closes #389
partially #390 (point 2)