[clang][bytecode] Reject typeid pointers from OffsetHelper (#163793)

Author: tbaederr

clang/lib/AST/ByteCode/Interp.h

@@ -2258,6 +2258,8 @@ std::optional<Pointer> OffsetHelper(InterpState &S, CodePtr OpPC,
       S.CCEDiag(S.Current->getSource(OpPC), diag::note_constexpr_array_index)
           << N << /*non-array*/ true << 0;
     return Pointer(Ptr.asFunctionPointer().getFunction(), N);
+  } else if (!Ptr.isBlockPointer()) {
+    return std::nullopt;
   }
 
   assert(Ptr.isBlockPointer());

clang/test/AST/ByteCode/typeid.cpp

@@ -63,9 +63,12 @@ namespace TypeidPtrInEvaluationResult {
 // Regression test for crash in ArrayElemPtrPop with typeid pointers. GH-163127
 namespace TypeidPtrRegression {
   void dontcrash() {
-    // this should just be an error and not an ICE
     constexpr auto res = ((void**)&typeid(int))[0]; // both-error {{must be initialized by a constant expression}} \
-                                                                // both-note {{cast that performs the conversions of a reinterpret_cast is not allowed in a constant expression}}
+                                                    // both-note {{cast that performs the conversions of a reinterpret_cast is not allowed in a constant expression}}
+  }
+  void dontcrash2() {
+    constexpr auto res = ((void**)&typeid(int))[1]; // both-error {{must be initialized by a constant expression}} \
+                                                    // both-note {{cast that performs the conversions of a reinterpret_cast is not allowed in a constant expression}}
   }
 }