Before You File a Proposal Please Confirm You Have Done The Following...

• I have searched for related issues and found none that match my proposal.
• I have searched the current rule list and found no rules that match my proposal.
• I have read the FAQ and my problem is not listed.

Relevant Package

ast-spec

My proposal is suitable for this project

• I believe my proposal would be useful to the broader TypeScript community (meaning it is not a niche proposal).

Description

Currently TSLiteralType is typed to accept Literal | TemplateLiteral | UnaryExpression | UpdateExpression

However this is unnecessarily permissive (playground):

• You cannot have null literals -- that is instead a TSNullKeyword
• You cannot have Regex literals -- they are currently a hard TS parser error
• You cannot have any UnaryExpression -- the only allowable operator is - for negative numbers -- type T = -1 / type U = -1n
• You cannot have any UpdateExpressions -- ++ and -- are both hard TS parser errors

Proposal:

• Remove UpdateExpression from the type
• Refine the Literal union to just the valid literals
• Refine the UnaryExpression to just the valid operators

Additional Info

No response