[clang] [analyzer] Suppress out of bounds reports after weak loop assumptions (PR #109804)

[Donát Nagy via cfe-commits]

================
@@ -212,6 +212,25 @@ typedef llvm::ImmutableMap<const LocationContext *, unsigned>
 REGISTER_TRAIT_WITH_PROGRAMSTATE(PendingArrayDestruction,
                                  PendingArrayDestructionMap)
 
+// This trait is used to heuristically filter out results produced from
+// execution paths that took "weak" assumptions within a loop.
+REGISTER_TRAIT_WITH_PROGRAMSTATE(SeenWeakLoopAssumption, bool)
+
+ProgramStateRef clang::ento::recordWeakLoopAssumption(ProgramStateRef State) {
+  return State->set<SeenWeakLoopAssumption>(true);
+}
+
+bool clang::ento::seenWeakLoopAssumption(ProgramStateRef State) {
+  return State->get<SeenWeakLoopAssumption>();
+}
----------------
NagyDonat wrote:

This bit doesn't have any "no longer needed" point -- if we made some shaky assumption for a loop condition, I want to suppress _all_ the ArrayBoundV2 reports that are reached through a path which takes that particular branch.

(By the way, each `ExplodedNode` has an associated `State`, which is essentially a big heap of traits that are introduced by various parts of the engine and various checkers; so yes, traits are contained in the egraph as well.)

https://github.com/llvm/llvm-project/pull/109804