[clang] [Clang] Make the SizeType, SignedSizeType and PtrdiffType be named sugar types instead of built-in types (PR #143653)

[Matheus Izvekov via cfe-commits]

https://github.com/mizvekov commented:

Thanks for this!

I have left a small review, but since I am traveling to the WG21 meeting, I can't look much into it for the next couple of weeks.

Also, please try this on the llvm compile time tracker, and take a look at any changes to the amount of AST nodes created when compiling some complex test case (there is a compiler option to print this, but I can't remember the spelling right now).

We want to make sure this doesn't regress performance.

https://github.com/llvm/llvm-project/pull/143653