[analyzer] RetainCount: Add support for OSRequiredCast().

It's a new API for custom RTTI in Apple IOKit/DriverKit framework that is
similar to OSDynamicCast() that's already supported, but crashes instead of
returning null (and therefore causing UB when the cast fails unexpectedly).
Kind of like cast_or_null<> as opposed to dyn_cast_or_null<> in LLVM's RTTI.

Historically, RetainCountChecker was responsible for modeling OSDynamicCast.
This is simply an extension of the same functionality.

Differential Revision: https://reviews.llvm.org/D63117

llvm-svn: 363891

1 files changed, 20 insertions, 1 deletions

diff --git a/clang/test/Analysis/osobject-retain-release.cpp b/clang/test/Analysis/osobject-retain-release.cpp
index 10ef144bf36..afcc2425835 100644
--- a/clang/test/Analysis/osobject-retain-release.cpp
+++ b/clang/test/Analysis/osobject-retain-release.cpp
@@ -1,9 +1,11 @@
 // RUN: %clang_analyze_cc1 -fblocks -analyze -analyzer-output=text\
-// RUN:                    -analyzer-checker=core,osx -verify %s
+// RUN:   -analyzer-checker=core,osx,debug.ExprInspection -verify %s
 
 #include "os_object_base.h"
 #include "os_smart_ptr.h"
 
+void clang_analyzer_eval(bool);
+
 struct OSIterator : public OSObject {
   static const OSMetaClass * const metaClass;
 };
@@ -483,6 +485,23 @@ void check_dynamic_cast() {
   arr->release();
 }
 
+void check_required_cast() {
+  OSArray *arr = OSRequiredCast(OSArray, OSObject::generateObject(1));
+  arr->release(); // no-warning
+}
+
+void check_cast_behavior(OSObject *obj) {
+  OSArray *arr1 = OSDynamicCast(OSArray, obj);
+  clang_analyzer_eval(arr1 == obj); // expected-warning{{TRUE}}
+                                    // expected-note@-1{{TRUE}}
+                                    // expected-note@-2{{Assuming 'arr1' is not equal to 'obj'}}
+                                    // expected-warning@-3{{FALSE}}
+                                    // expected-note@-4   {{FALSE}}
+  OSArray *arr2 = OSRequiredCast(OSArray, obj);
+  clang_analyzer_eval(arr2 == obj); // expected-warning{{TRUE}}
+                                    // expected-note@-1{{TRUE}}
+}
+
 unsigned int check_dynamic_cast_no_null_on_orig(OSObject *obj) {
   OSArray *arr = OSDynamicCast(OSArray, obj);
   if (arr) {