Complication with trivial type for C++26

[wusatosi]

Trivial type trait will be deprecated in C++26, we need to make sure we omit trivial type check and its related facilities to be compatible with C++26.

[jbab]

As of R14, the specification still references std::is_trivial. I suggest to hold back any changes until the specification catches up.

[wusatosi]

As of R14, the specification still references std::is_trivial. I suggest to hold back any changes until the specification catches up.

The paper has been accepted into the standard draft, per my understanding the paper itself will not be updated anymore, all update will be done via another paper or direct edit to the draft.

P3247 Deprecate the notion of trivial types has already been accepted into the draft and changed the wording of inplace_vector, see: cplusplus/draft#7439

Specific diff here: https://github.com/cplusplus/draft/pull/7439/files#diff-3b5851f7056b7c68cb3ba2ab51cf0b75a780c6a11e5e181770067700454ace7b

[wusatosi]

You can also check here for the latest draft: https://eel.is/c++draft/inplace.vector

All reference to trivial type has already been replaced.

[wusatosi]

Given #67, let's do trivial type check when no trivial union.