[llvm-bugs] [Bug 43366] New: If dyn_cast<TYPE>(X) is non-null, assume X is non-null as well?

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=43366

            Bug ID: 43366
           Summary: If dyn_cast<TYPE>(X) is non-null, assume X is non-null
                    as well?
           Product: clang
           Version: unspecified
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Static Analyzer
          Assignee: dcoughlin at apple.com
          Reporter: llvm-dev at redking.me.uk
                CC: dcoughlin at apple.com, llvm-bugs at lists.llvm.org,
                    noqnoqneo at gmail.com

Noticed here:

https://llvm.org/reports/scan-build/report-AArch64TargetTransformInfo.cpp-getValueType-12-1.html#EndPath

if (auto *VTy = dyn_cast<VectorType>(Ty)) {
  Type *EltTy = VTy->getElementType();
  // Lower vectors of pointers to native pointer types.
  if (auto *PTy = dyn_cast<PointerType>(EltTy)) {
    EVT PointerTy(getPointerTy(DL, PTy->getAddressSpace()));
    EltTy = PointerTy.getTypeForEVT(Ty->getContext());
  }
  return EVT::getVectorVT(Ty->getContext(), EVT::getEVT(EltTy, false),
                          VTy->getElementCount());
}


The warning says that Ty->getContext() can be a null pointer, but if we know
that VTy is non-null and is a dyn_cast from Ty, then shouldn't Ty be known to
be non-null?

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