[analyzer] Fix bug in isInevitablySinking

[george.karpenkov]

Summary

If the non-sink report is generated at the exit node, it will be suppressed by the current functionality in isInevitablySinking, as it only checks the successors of the block, but not the block itself.

I don't have an isolated test yet, but it does show up in retain-count-checker.

[NoQ]

Yup. Ugh.

cfe/trunk/lib/StaticAnalyzer/Core/BugReporter.cpp

static bool isInevitablySinking(const ExplodedNode *N) {
   llvm::SmallPtrSet<const CFGBlock *, 32> Visited;
 
   DFSWorkList.push_back(StartBlk);
   while (!DFSWorkList.empty()) {
     const CFGBlock *Blk = DFSWorkList.back();
     DFSWorkList.pop_back();
     Visited.insert(Blk);
 
-    for (const auto &Succ : Blk->succs()) {
-      if (const CFGBlock *SuccBlk = Succ.getReachableBlock()) {
-        if (SuccBlk == &Cfg.getExit()) {
-          // If at least one path reaches the CFG exit, it means that control is
-          // returned to the caller. For now, say that we are not sure what
-          // happens next. If necessary, this can be improved to analyze
-          // the parent StackFrameContext's call site in a similar manner.
-          return false;
-        }
+    if (Blk == &Cfg.getExit())
 
+    for (const auto &Succ : Blk->succs()) {
+      if (const CFGBlock *SuccBlk = Succ.getReachableBlock()) {
         if (!isImmediateSinkBlock(SuccBlk) && !Visited.count(SuccBlk)) {
           // If the block has reachable child blocks that aren't no-return,
           // add them to the worklist.
           DFSWorkList.push_back(SuccBlk);
         }
       }
     }
   }