[clang] [clang-tools-extra] WIP: Extend SourceLocation to 64 bits. (PR #146314)

[Haojian Wu via cfe-commits]

hokein wrote:

> I did a light pass of the 1st 1/4 of this or so. The smuggling back and forth to raw-encoding seems strange? WHy are we doing that here?

In this patch, to keep AST node size as small as possible, we're using 40 bits of `StmtBits` to store the SourceLocation, we need this back-and-forth conversion.

For the `DeclarationName`, you're right — we can just store the SourceLocation directly and avoid the raw-encoding round-trip.



https://github.com/llvm/llvm-project/pull/146314