bare infinitives

But all he'd tried to do (as he shouted at Uncle Vernon through the locked door of his cupboard) was jump behind the big trash cans outside the kitchen doors. Harry supposed that the wind must have caught him in mid- jump. (Harry Potter and the Sorcerer's Stone)
A great thing to do is dance the night away. (English Syntax and Argumentation, Bas Aarts)

As long as there is a to-infinitive in the subject just like the two examples, can we use a bare infinitive after the copular? (I want to know if there are some regulations in using bare infinitives: for example, the subject has to have ‘all, what, anything, etc’)