[analyzer] Fix crash in RunLoopAutoreleaseChecker on empty children

[NoQ]

clang/lib/StaticAnalyzer/Checkers/RunLoopAutoreleaseLeakChecker.cpp

68 ↗

(On Diff #158069)

The good point thing.

lib/StaticAnalyzer/Checkers/RunLoopAutoreleaseLeakChecker.cpp

 
 namespace {
 
 const char * RunLoopBind = "NSRunLoopM";
 const char * RunLoopRunBind = "RunLoopRunM";
 const char * OtherMsgBind = "OtherMessageSentM";
 const char * AutoreleasePoolBind = "AutoreleasePoolM";
 
-class RunLoopAutoreleaseLeakChecker : public Checker<
-                                      check::ASTCodeBody> {
+class RunLoopAutoreleaseLeakChecker : public Checker<check::ASTCodeBody> {
 
 public:
   void checkASTCodeBody(const Decl *D,
                         AnalysisManager &AM,
                         BugReporter &BR) const;
 
 };
 
 } // end anonymous namespace
 
 
 using TriBoolTy = Optional<bool>;
 using MemoizationMapTy = llvm::DenseMap<const Stmt *, Optional<TriBoolTy>>;
 
 static TriBoolTy
 seenBeforeRec(const Stmt *Parent, const Stmt *A, const Stmt *B,
               MemoizationMapTy &Memoization) {
   for (const Stmt *C : Parent->children()) {
+    if (!C) continue;
+
     if (C == A)
       return true;
 
     if (C == B)
       return false;
 
     Optional<TriBoolTy> &Cached = Memoization[C];
     if (!Cached)

test/Analysis/Checkers/RunLoopAutoreleaseLeakChecker.m

 }
 
 void runloop_init_before_two_objects() { // Warning: object created before the loop.
   @autoreleasepool {
     NSObject *object = [[NSObject alloc] init]; // expected-warning{{Temporary objects allocated in the autorelease pool followed by the launch of main run loop may never get released; consider moving them to a separate autorelease pool}}
     NSObject *object2 = [[NSObject alloc] init]; // no-warning, warning on the first one is enough.
     (void) object;
     (void) object2;
-    [[NSRunLoop mainRunLoop] run]; 
+    [[NSRunLoop mainRunLoop] run];
   }
 }
 
 void runloop_no_autoreleasepool() {
   NSObject *object = [[NSObject alloc] init]; // no-warning
   (void)object;
   [[NSRunLoop mainRunLoop] run];
 }
 
 void runloop_init_after() { // No warning: objects created after the loop
   @autoreleasepool {
     [[NSRunLoop mainRunLoop] run]; 
     NSObject *object = [[NSObject alloc] init]; // no-warning
     (void) object;
   }
 }
 
+void no_crash_on_empty_children() {
+  @autoreleasepool {
+    for (;;) {}
+    NSObject *object = [[NSObject alloc] init]; // expected-warning{{Temporary objects allocated in the autorelease pool followed by the launch of main run loop may never get released; consider moving them to a separate autorelease pool}}
+    [[NSRunLoop mainRunLoop] run];
+    (void) object;
+  }
+}
+
 #endif
 
 #ifdef AP1
 int main() {
     NSObject *object = [[NSObject alloc] init]; // expected-warning{{Temporary objects allocated in the autorelease pool of last resort followed by the launch of main run loop may never get released; consider moving them to a separate autorelease pool}}
     (void) object;
     [[NSRunLoop mainRunLoop] run]; 
     return 0;