[clang] [WIP] [Modules] Delay reading type source info of the preferred_name attribute. (PR #122250)

[Viktoriia Bakalova via cfe-commits]

VitaNuo wrote:

> BTW, it is better to have better explanation in the summary. I know you explained it in the issue. But it will be better for other readers after you land the PR.

Thanks @ChuanqiXu9, I have added a detailed summary https://github.com/llvm/llvm-project/pull/122726.

After some conversations with @ilya-biryukov, we're thinking that it's better to land the change for the preferred_name attribute first. It's fairly unclear if the approach in https://github.com/llvm/llvm-project/pull/122726 generalizes to all attributes.

Besides, since we're settled that https://github.com/llvm/llvm-project/pull/122726 is a better approach to fixing the issue, I will close this PR so that we can move all the discussions to a single location.

https://github.com/llvm/llvm-project/pull/122250