Auto merge of #1984 - RalfJung:rustup, r=RalfJung

rustup

Author: bors

rust-version

@@ -1 +1 @@
-b8967b0d52a2ba5f0c9da0da03e78ccba5534e4a
+3d127e2040b57157936f5f24e114a8b4c9a505ef

tests/compile-fail/validity/execute_memory.rs

@@ -6,5 +6,5 @@ fn main() {
     let x : fn() = f;
     let y : *mut u8 = unsafe { mem::transmute(x) };
     let y = y.wrapping_offset(1);
-    let _x : fn() = unsafe { mem::transmute(y) }; //~ ERROR expected a function pointer
+    let _x : fn() = unsafe { mem::transmute(y) }; //~ ERROR encountered a potentially null function pointer
 }

tests/compile-fail/validity/fn_ptr_offset.rs

@@ -0,0 +1,5 @@
+#![allow(invalid_value)]
+
+fn main() {
+    let _b: fn() = unsafe { std::mem::transmute(0usize) }; //~ ERROR encountered a potentially null function pointer
+}

tests/compile-fail/validity/invalid_fnptr_null.rs

@@ -6,5 +6,5 @@ union MyUninit {
 }
 
 fn main() {
-    let _b = unsafe { MyUninit { init: () }.uninit }; //~ ERROR encountered uninitialized bytes, but expected a function pointer
+    let _b = unsafe { MyUninit { init: () }.uninit }; //~ ERROR encountered uninitialized bytes
 }

tests/compile-fail/validity/invalid_fnptr_uninit.rs

@@ -1,3 +1,5 @@
+use std::mem;
+
 trait Answer {
     fn answer() -> Self;
 }
@@ -56,4 +58,13 @@ fn main() {
     assert!(return_fn_ptr(g) == g);
     assert!(return_fn_ptr(g) as unsafe fn() -> i32 == g as fn() -> i32 as unsafe fn() -> i32);
     assert!(return_fn_ptr(f) != f);
+
+    // Any non-null value is okay for function pointers.
+    unsafe {
+        let _x: fn() = mem::transmute(1usize);
+        let mut b = Box::new(42);
+        let ptr = &mut *b as *mut _;
+        drop(b);
+        let _x: fn() = mem::transmute(ptr);
+    }
 }