adjust for get_fn signature change

Author: RalfJung

src/shims/foreign_items.rs

@@ -317,7 +317,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 //     vtable_ptr: *mut usize,
                 // ) -> u32
                 // We abort on panic, so not much is going on here, but we still have to call the closure.
-                let f = this.read_scalar(args[0])?.to_ptr()?;
+                let f = this.read_scalar(args[0])?.not_undef()?;
                 let data = this.read_scalar(args[1])?.not_undef()?;
                 let f_instance = this.memory().get_fn(f)?.as_instance()?;
                 this.write_null(dest)?;
@@ -637,14 +637,12 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 let key_ptr = this.read_scalar(args[0])?.not_undef()?;
 
                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
-                let dtor = match this.read_scalar(args[1])?.not_undef()? {
-                    Scalar::Ptr(dtor_ptr) => Some(this.memory().get_fn(dtor_ptr)?.as_instance()?),
-                    Scalar::Raw { data: 0, size } => {
-                        // NULL pointer
-                        assert_eq!(size as u64, this.memory().pointer_size().bytes());
-                        None
-                    },
-                    Scalar::Raw { .. } => return err!(ReadBytesAsPointer),
+                let dtor = match this.read_scalar(args[1])?.not_undef()?.to_bits_or_ptr(this.memory().pointer_size(), tcx) {
+                    Err(dtor_ptr) =>
+                        Some(this.memory().get_fn(dtor_ptr.into())?.as_instance()?),
+                    Ok(0) => // NULL pointer
+                        None,
+                    Ok(_) => return err!(ReadBytesAsPointer),
                 };
 
                 // Figure out how large a pthread TLS key actually is.