[clang] [Clang] Enable -fpointer-tbaa by default. (PR #117244)

[Florian Hahn via cfe-commits]

fhahn wrote:

> I think this is a strict improvement over the general 'fstrict-aliasing' mode we already have, and I see little value in maintaining separate levels of strict aliasing conformance long term.
> 
> I think it would not be a good situation for users to rely on some level of strict aliasing violations, by clang accepting some bugs, rejecting others, without a clear line separating them.
> 
> I'd favor not having the flag, with 'fno-strict-aliasing' still being enforced. I don't have strong objections against the new flag, if it's only temporary, with a clear goalpost for removing it.

I agree that long-term we should remove the separate flag, maybe after one or two releases. Initially I expect it will help users during the transition phase (and also us during bug triage to quickly identify if an issue is related to the new behavior)

https://github.com/llvm/llvm-project/pull/117244