[clang][dataflow] Don't crash when constructing an array of records.

[mboehme]

Summary

When I wrote https://reviews.llvm.org/D155446, I assumed that a CXXConstructExpr would always have record type, but this isn't true: It can have array type when constructing an array of records. The code would crash in this situation because createValue() would return null.

This patch includes a test that reproduces the crash without the other changes in the patch.

[mboehme]

CI failures look unrelated

clang/lib/Analysis/FlowSensitive/Transfer.cpp

if (ConstructorDecl->isCopyOrMoveConstructor()) {
                      Env.getValue(*Arg, SkipPast::Reference))) {
         auto &Val = *cast<StructValue>(Env.createValue(S->getType()));
         Env.setValueStrict(*S, Val);
         copyRecord(ArgVal->getAggregateLoc(), Val.getAggregateLoc(), Env);
       }
       return;
     }
 
+    // `CXXConstructExpr` can have array type if default-initializing an array
+    // of records, and we currently can't create values for arrays. So check if
+    // we've got a record type.
+    if (S->getType()->isRecordType()) {
       auto &InitialVal = *cast<StructValue>(Env.createValue(S->getType()));
       copyRecord(InitialVal.getAggregateLoc(), Env.getResultObjectLocation(*S),
                  Env);
+    }
 
     transferInlineCall(S, ConstructorDecl);
   }
 
   void VisitCXXOperatorCallExpr(const CXXOperatorCallExpr *S) {
     if (S->getOperator() == OO_Equal) {
       assert(S->getNumArgs() == 2);
 

clang/unittests/Analysis/FlowSensitive/TransferTest.cpp

runDataflow(
         ASSERT_THAT(BarDecl, NotNull());
 
         const auto *FooLoc =
             cast<AggregateStorageLocation>(Env.getStorageLocation(*FooDecl));
         EXPECT_TRUE(isa<IntegerValue>(getFieldValue(FooLoc, *BarDecl, Env)));
       });
 }
 
+TEST(TransferTest, StructArrayVarDecl) {
+  std::string Code = R"(
+    struct A {};
+
+    void target() {
+      A Array[2];
+      // [[p]]
+    }
+  )";
+  runDataflow(
+      Code,
+      [](const llvm::StringMap<DataflowAnalysisState<NoopLattice>> &Results,
+         ASTContext &ASTCtx) {
+        const Environment &Env = getEnvironmentAtAnnotation(Results, "p");
+
+        const ValueDecl *ArrayDecl = findValueDecl(ASTCtx, "Array");
+
+        // We currently don't create values for arrays.
+        ASSERT_THAT(Env.getValue(*ArrayDecl), IsNull());
+      });
+}
+
 TEST(TransferTest, ClassVarDecl) {
   std::string Code = R"(
     class A {
      public:
       int Bar;
     };
 
     void target() {