Merge pull request #24 from JohnTitor/fix-dereference-null-ptr

Fix the `deref_nullptr` warning

src/lib.rs

@@ -1019,9 +1019,15 @@ impl TestGenerator {
             }
 
             macro_rules! offset_of {
-                ($ty:ident, $field:ident) => (
-                    (&((*(0 as *const $ty)).$field)) as *const _ as u64
-                )
+                ($ty:ident, $field:ident) => ({
+                    let zeroed_ty = std::mem::zeroed::<$ty>();
+                    let ty_ptr = &zeroed_ty as *const $ty;
+                    let field_ptr = std::ptr::addr_of!(zeroed_ty.$field);
+                    let ty_address = ty_ptr as u64;
+                    let field_address = field_ptr as u64;
+                    std::mem::forget(zeroed_ty);
+                    field_address.checked_sub(ty_address).unwrap()
+                })
             }
 
         "#

testcrate/src/bin/t1.rs

@@ -1,5 +1,6 @@
 #![cfg(not(test))]
 #![deny(warnings)]
+#![allow(unaligned_references)]
 
 use libc::*;
 use testcrate::t1::*;

testcrate/src/bin/t1_cxx.rs

@@ -1,5 +1,6 @@
 #![cfg(not(test))]
 #![deny(warnings)]
+#![allow(unaligned_references)]
 
 use libc::*;
 use testcrate::t1::*;

testcrate/src/bin/t2.rs

@@ -1,5 +1,6 @@
 #![cfg(not(test))]
 #![deny(warnings)]
+#![allow(unaligned_references)]
 
 use testcrate::t2::*;
 

testcrate/src/bin/t2_cxx.rs

@@ -1,5 +1,6 @@
 #![cfg(not(test))]
 #![deny(warnings)]
+#![allow(unaligned_references)]
 
 use testcrate::t2::*;