[clang] [CodeGen] Fix handling of nullptr in initializers (PR #137364)

[Eli Friedman via cfe-commits]

================
@@ -121,6 +121,7 @@ CAST_OPERATION(FunctionToPointerDecay)
 /// CK_NullToPointer - Null pointer constant to pointer, ObjC
 /// pointer, or block pointer.
 ///   (void*) 0
+///   (void*) nullptr
----------------
efriedma-quic wrote:

Maybe we can simplify it to just:

```
/// CK_NullToPointer - Null pointer constant to pointer, ObjC
/// pointer, block pointer, or std::nullptr_t.
```

https://github.com/llvm/llvm-project/pull/137364