[NFC][CLANG] Fix static code analyzer concerns

[Manna]

Summary

Reported by Static Analyzer Tool:

Dereference null return value

Inside "ExprConstant.cpp" file, in <unnamed>::​RecordExprEvaluator::​VisitCXXStdInitializerListExpr(clang::​CXXStdInitializerListExpr const *): Return value of function which returns null is dereferenced without checking.

bool RecordExprEvaluator::VisitCXXStdInitializerListExpr(
 const CXXStdInitializerListExpr *E) {
     // returned_null: getAsConstantArrayType returns nullptr (checked 81 out of 93 times). 
     //var_assigned: Assigning: ArrayType = nullptr return value from getAsConstantArrayType.
  const ConstantArrayType *ArrayType =
     Info.Ctx.getAsConstantArrayType(E->getSubExpr()->getType());
  LValue Array;
  //Condition !EvaluateLValue(E->getSubExpr(), Array, this->Info, false), taking false branch.
  if (!EvaluateLValue(E->getSubExpr(), Array, Info))
   return false;

  // Get a pointer to the first element of the array.
     	
 //Dereference null return value (NULL_RETURNS)
//dereference: Dereferencing a pointer that might be nullptr ArrayType when calling addArray. 
  Array.addArray(Info, E, ArrayType);

This patch adds an assert.

[erichkeane]

clang/lib/AST/ExprConstant.cpp

10172

I think this ends up being a regression if the LValue doesn't evaluate right. This should probably go down near 10179.

[Manna]

Thank you @erichkeane for reviews. I have updated patch to avoid regression if the LValue doesn't evaluate right.

clang/lib/AST/ExprConstant.cpp

return HandleConstructorCall(E, This, Info.CurrentCall->Arguments,
                                cast<CXXConstructorDecl>(Definition), Info,
                                Result);
 }
 
 bool RecordExprEvaluator::VisitCXXStdInitializerListExpr(
     const CXXStdInitializerListExpr *E) {
   const ConstantArrayType *ArrayType =
       Info.Ctx.getAsConstantArrayType(E->getSubExpr()->getType());
 
   LValue Array;
   if (!EvaluateLValue(E->getSubExpr(), Array, Info))
     return false;
 
+  assert(ArrayType && "unexpected type for array initializer");
+
   // Get a pointer to the first element of the array.
   Array.addArray(Info, E, ArrayType);
 
   auto InvalidType = [&] {
     Info.FFDiag(E, diag::note_constexpr_unsupported_layout)
       << E->getType();
     return false;
   };