help needed: How to get during compile time the base class of casted C++ object inside static_cast<> and dynamic_cast<> and the pointer of the casted object

I want to detect bad casts in C++ code by using the Clang
compiler. The approach is similar to what Caver and TypeSan do but
without using the compiler-rt.

Caver and TypeSan:

For example if I have the following C++ code snippet where I want to
cast object b into
object D.

D* obj = static_cast<D*>(b);

from where (inside Clang, LTO, thinLTO, etc.) can I get the base class
of D and the base class ob b. Is this
available in the Clang compiler or LTO?

Also, if b is an object of a virtual Class (class with inherited or its
own virtual functions) can I get its virtual pointer at compile time
by using the LTO?

I found out that in CodeGen/CGExpr.cpp the explicit case "BaseToDerived" is
handled and you can retrieve TypeSourceInfo using the function
getTypeInfoAsWritten(). It seems that this information is enough to get
the exact type of this cast at compile-time and should also work for
Template programming, as my, understanding is that Clang should have
abstracted the code into, specific types at this point.

Am I wrong here?

Is there any case where the type of the objects used inside the cast
not known at compile time? Can the,
'real' type be hidden behind a pointer?

I want to detect bad casts in C++ code by using the Clang
compiler. The approach is similar to what Caver and TypeSan do but
without using the compiler-rt.

Caver and TypeSan:
https://www.usenix.org/system/files/conference/usenixsecurity15/sec15-paper-lee.pdf
https://nebelwelt.net/publications/files/16CCS2.pdf

For example if I have the following C++ code snippet where I want to
cast object b into
object D.

D* obj = static_cast<D*>(b);

from where (inside Clang, LTO, thinLTO, etc.) can I get the base class
of D and the base class ob b. Is this
available in the Clang compiler or LTO?

This is available in the Clang AST and this is the most straightforward way to manipulate this. Usually it is not available at the LLVM level (no notion of class or hierarchy it present there), but for the CFI and LTO devirtualization infrastructure described here: http://llvm.org/docs/TypeMetadata.html

Also, if b is an object of a virtual Class (class with inherited or its
own virtual functions) can I get its virtual pointer at compile time
by using the LTO?

I don’t understand this question. What do you mean by “virtual pointer”? The Vtable?
Usually you can’t get it statically, you have to load b (that’s ABI dependent, but clang has the information).

I found out that in CodeGen/CGExpr.cpp the explicit case "BaseToDerived" is
handled and you can retrieve TypeSourceInfo using the function
getTypeInfoAsWritten(). It seems that this information is enough to get
the exact type of this cast at compile-time and should also work for
Template programming, as my, understanding is that Clang should have
abstracted the code into, specific types at this point.

Am I wrong here?

Is there any case where the type of the objects used inside the cast
not known at compile time? Can the,
'real' type be hidden behind a pointer?

You didn’t provide enough context in your previous snippet, but consider this:

void foo(B *b) {
  D* obj = static_cast<D*>(b);
}

You don’t know that b points to an instance of B, it could be any subclass of B.