☂️ Syntax errors raised by the compiler

[dhruvmanila]

This is an umbrella issue to collect all the syntax errors that are raised by the CPython compiler. These are different than the ones that are raised by the parser. IOW, the source code which raises these errors are valid as per the grammar.

• Ruff fails to reject invalid syntax in annotation scopes #11118
• Ruff fails to detect duplicate type parameter names #11119
• Irrefutable patterns are syntax errors
  • SyntaxError: name capture 'x' makes remaining patterns unreachable
  • SyntaxError: wildcard makes remaining patterns unreachable
• Multiple assignments to name 'a' in pattern (case [a, b, a]:)
• Ruff doesn't raise syntax error for single starred assignment target #13759
• No syntax error for [(a := ...) for a in b] #14395

A lot of them are mentioned in this comment. These all would be part of E999 rule.