[analyzer] Fixing SVal::getType returns Null Type for NonLoc::ConcreteInt in boolean type

[OikawaKirie]

Summary

In method TypeRetrievingVisitor::VisitConcreteInt, ASTContext::getIntTypeForBitwidth is used to get the type for ConcreteInts.
However, the getter in ASTContext cannot handle the boolean type with the bit width of 1, which will make method SVal::getType return a Null Type.
In this patch, a check for this case is added to fix this problem by returning the bool type directly when the bit width is 1.

[martong]

Thanks! LGTM!

clang/lib/StaticAnalyzer/Core/SVals.cpp

public:
   QualType VisitLocMemRegionVal(loc::MemRegionVal MRV) {
     return Visit(MRV.getRegion());
   }
   QualType VisitLocGotoLabel(loc::GotoLabel GL) {
     return QualType{Context.VoidPtrTy};
   }
   template <class ConcreteInt> QualType VisitConcreteInt(ConcreteInt CI) {
     const llvm::APSInt &Value = CI.getValue();
+    if (1 == Value.getBitWidth())
+      return Context.BoolTy;
     return Context.getIntTypeForBitwidth(Value.getBitWidth(), Value.isSigned());
   }
   QualType VisitLocConcreteInt(loc::ConcreteInt CI) {
     return VisitConcreteInt(CI);
   }
   QualType VisitNonLocConcreteInt(nonloc::ConcreteInt CI) {
     return VisitConcreteInt(CI);
   }

clang/unittests/StaticAnalyzer/SValTest.cpp

 //===----------------------------------------------------------------------===//
 //                                 Actual tests
 //===----------------------------------------------------------------------===//
 
 SVAL_TEST(GetConstType, R"(
 void foo() {
   int x = 42;
   int *y = nullptr;
+  bool z = true;
 })") {
   SVal X = getByName("x");
   ASSERT_FALSE(X.getType(Context).isNull());
   EXPECT_EQ(Context.IntTy, X.getType(Context));
 
   SVal Y = getByName("y");
   ASSERT_FALSE(Y.getType(Context).isNull());
   expectSameSignAndBitWidth(Context.getUIntPtrType(), Y.getType(Context),
                             Context);
+
+  SVal Z = getByName("z");
+  ASSERT_FALSE(Z.getType(Context).isNull());
+  EXPECT_EQ(Context.BoolTy, Z.getType(Context));
 }
 
 SVAL_TEST(GetLocAsIntType, R"(
 void foo(int *x) {
   long int a = (long long int)x;
   unsigned b = (long long unsigned)&a;
   int c = (long long int)nullptr;
 })") {