[Analysis] Prevent revisiting block when searching for noreturn vars (#150582)

When searching for noreturn variable initializations, do not visit CFG
blocks that are already visited, it prevents hanging the analysis.

It must fix llvm/llvm-project#150336.

(cherry picked from commit 330b40e)

Author: spavloff

clang/lib/Sema/AnalysisBasedWarnings.cpp

@@ -503,8 +503,12 @@ static bool areAllValuesNoReturn(const VarDecl *VD, const CFGBlock &VarBlk,
 
   TransferFunctions TF(VD);
   BackwardDataflowWorklist Worklist(*AC.getCFG(), AC);
+  llvm::DenseSet<const CFGBlock *> Visited;
   Worklist.enqueueBlock(&VarBlk);
   while (const CFGBlock *B = Worklist.dequeue()) {
+    if (Visited.contains(B))
+      continue;
+    Visited.insert(B);
     // First check the current block.
     for (CFGBlock::const_reverse_iterator ri = B->rbegin(), re = B->rend();
          ri != re; ++ri) {

clang/test/SemaCXX/noreturn-weverything.c

@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -fsyntax-only %s -Weverything
+
+void free(void *);
+typedef void (*set_free_func)(void *);
+struct Method {
+  int nparams;
+  int *param;
+};
+void selelem_free_method(struct Method* method, void* data) {
+    set_free_func free_func = 0;
+    for (int i = 0; i < method->nparams; ++i)
+        free(&method->param[i]);
+    if (data && free_func)
+        free_func(data);
+}