1 files changed, 73 insertions, 0 deletions
diff --git a/src/test/ui/run-pass/structs-enums/enum-null-pointer-opt.rs b/src/test/ui/run-pass/structs-enums/enum-null-pointer-opt.rs
new file mode 100644
index 00000000000..34ed589d418
--- /dev/null
+++ b/src/test/ui/run-pass/structs-enums/enum-null-pointer-opt.rs
@@ -0,0 +1,73 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::mem::size_of;
+use std::num::NonZeroUsize;
+use std::ptr::NonNull;
+use std::rc::Rc;
+use std::sync::Arc;
+
+trait Trait { fn dummy(&self) { } }
+trait Mirror { type Image; }
+impl<T> Mirror for T { type Image = T; }
+struct ParamTypeStruct<T>(T);
+struct AssocTypeStruct<T>(<T as Mirror>::Image);
+
+fn main() {
+    // Functions
+    assert_eq!(size_of::<fn(isize)>(), size_of::<Option<fn(isize)>>());
+    assert_eq!(size_of::<extern "C" fn(isize)>(), size_of::<Option<extern "C" fn(isize)>>());
+
+    // Slices - &str / &[T] / &mut [T]
+    assert_eq!(size_of::<&str>(), size_of::<Option<&str>>());
+    assert_eq!(size_of::<&[isize]>(), size_of::<Option<&[isize]>>());
+    assert_eq!(size_of::<&mut [isize]>(), size_of::<Option<&mut [isize]>>());
+
+    // Traits - Box<Trait> / &Trait / &mut Trait
+    assert_eq!(size_of::<Box<Trait>>(), size_of::<Option<Box<Trait>>>());
+    assert_eq!(size_of::<&Trait>(), size_of::<Option<&Trait>>());
+    assert_eq!(size_of::<&mut Trait>(), size_of::<Option<&mut Trait>>());
+
+    // Pointers - Box<T>
+    assert_eq!(size_of::<Box<isize>>(), size_of::<Option<Box<isize>>>());
+
+    // The optimization can't apply to raw pointers
+    assert!(size_of::<Option<*const isize>>() != size_of::<*const isize>());
+    assert!(Some(0 as *const isize).is_some()); // Can't collapse None to null
+
+    struct Foo {
+        _a: Box<isize>
+    }
+    struct Bar(Box<isize>);
+
+    // Should apply through structs
+    assert_eq!(size_of::<Foo>(), size_of::<Option<Foo>>());
+    assert_eq!(size_of::<Bar>(), size_of::<Option<Bar>>());
+    // and tuples
+    assert_eq!(size_of::<(u8, Box<isize>)>(), size_of::<Option<(u8, Box<isize>)>>());
+    // and fixed-size arrays
+    assert_eq!(size_of::<[Box<isize>; 1]>(), size_of::<Option<[Box<isize>; 1]>>());
+
+    // Should apply to NonZero
+    assert_eq!(size_of::<NonZeroUsize>(), size_of::<Option<NonZeroUsize>>());
+    assert_eq!(size_of::<NonNull<i8>>(), size_of::<Option<NonNull<i8>>>());
+
+    // Should apply to types that use NonZero internally
+    assert_eq!(size_of::<Vec<isize>>(), size_of::<Option<Vec<isize>>>());
+    assert_eq!(size_of::<Arc<isize>>(), size_of::<Option<Arc<isize>>>());
+    assert_eq!(size_of::<Rc<isize>>(), size_of::<Option<Rc<isize>>>());
+
+    // Should apply to types that have NonZero transitively
+    assert_eq!(size_of::<String>(), size_of::<Option<String>>());
+
+    // Should apply to types where the pointer is substituted
+    assert_eq!(size_of::<&u8>(), size_of::<Option<ParamTypeStruct<&u8>>>());
+    assert_eq!(size_of::<&u8>(), size_of::<Option<AssocTypeStruct<&u8>>>());
+}