Full name of submitter (unless configured in github; will be published with the issue): Tim Song

Reference (section label): [temp.dep.expr]

Link to reflector thread (if any):

Issue description:

Presumably an expression of the form x.[:y:] is type-dependent if the splice-specifier is dependent, even if x is not. https://eel.is/c++draft/temp.dep.expr#5 needs to be updated to handle that case.

Suggested resolution: