Thread Safety Analysis: Support warning on passing/returning pointers to guarded variables
Introduce `-Wthread-safety-pointer` to warn when passing or returning
pointers to guarded variables or guarded data. This is is analogous to
`-Wthread-safety-reference`, which performs similar checks for C++
references.
Adding checks for pointer passing is required to avoid false negatives
in large C codebases, where data structures are typically implemented
through helpers that take pointers to instances of a data structure.
The feature is planned to be enabled by default under `-Wthread-safety`
in the next release cycle. This gives time for early adopters to address
new findings.
Pull Request: https://github.com/llvm/llvm-project/pull/127396