[analyzer] Fix inf recursion in StackAddrEscapeChecker for self referencing blocks (#169208)

Objective-C blocks are like lambdas. They have captures, just like lambdas.
However, they can also implicitly capture themselves unlike lambdas.

This means that when walking the captures of a block, we may end up in
infinite recursion. This is not possible with lambdas, but happened in
practice with blocks downstream.

In this patch, I just use a set to keep track of the visited MemRegions.

Note that theoretically, there is nothing preventing usual lambdas or
functors from falling for the same trap, but probably slightly more
difficult to do so. You would likely need a pointer to itself, etc. I'll
not speculate here.

This inf recursion was likely caused by #126620, released in clang-21.

rdar://162215172
2 files changed
tree: 8389980461db04f3a9bdb7c861ff736bf1a4c440
  1. .ci/
  2. .github/
  3. bolt/
  4. clang/
  5. clang-tools-extra/
  6. cmake/
  7. compiler-rt/
  8. cross-project-tests/
  9. flang/
  10. flang-rt/
  11. libc/
  12. libclc/
  13. libcxx/
  14. libcxxabi/
  15. libsycl/
  16. libunwind/
  17. lld/
  18. lldb/
  19. llvm/
  20. llvm-libgcc/
  21. mlir/
  22. offload/
  23. openmp/
  24. orc-rt/
  25. polly/
  26. runtimes/
  27. third-party/
  28. utils/
  29. .clang-format
  30. .clang-format-ignore
  31. .clang-tidy
  32. .git-blame-ignore-revs
  33. .gitattributes
  34. .gitignore
  35. .mailmap
  36. CODE_OF_CONDUCT.md
  37. CONTRIBUTING.md
  38. LICENSE.TXT
  39. pyproject.toml
  40. README.md
  41. SECURITY.md
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