[analyzer] Avoid contradicting assumption in tainted div-by-0 error node (#144491)

This patch corrects the state of the error node generated by the
core.DivideZero checker when it detects potential division by zero
involving a tainted denominator.

The checker split in

https://github.com/llvm/llvm-project/pull/106389/commits/91ac5ed10a154410c246d985752c1bbfcf23b105
started to introduce a conflicting assumption about the denominator into
the error node:
Node with the Bug Report "Division by a tainted value, possibly zero"
has an assumption "denominator != 0".

This has been done as a shortcut to continue analysis with the correct
assumption *after* the division - if we proceed, we can only assume the
denominator was not zero. However, this assumption is introduced
one-node too soon, leading to a self-contradictory error node.

In this patch, I make the error node with assumption of zero denominator
fatal, but allow analysis to continue on the second half of the state
split with the assumption of non-zero denominator.

---

CPP-6376
2 files changed
tree: 04214ff6d254bef8cd30160da0a3a2f2b04e30bb
  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. libunwind/
  16. lld/
  17. lldb/
  18. llvm/
  19. llvm-libgcc/
  20. mlir/
  21. offload/
  22. openmp/
  23. polly/
  24. pstl/
  25. runtimes/
  26. third-party/
  27. utils/
  28. .clang-format
  29. .clang-format-ignore
  30. .clang-tidy
  31. .git-blame-ignore-revs
  32. .gitattributes
  33. .gitignore
  34. .mailmap
  35. CODE_OF_CONDUCT.md
  36. CONTRIBUTING.md
  37. LICENSE.TXT
  38. pyproject.toml
  39. README.md
  40. SECURITY.md
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