Add initial attempt at ui/nll test for maybe-initialized drop

Author: Nashenas88

src/test/ui/nll/maybe-initialized-drop.rs

@@ -0,0 +1,65 @@
+// Copyright 2017 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.
+// revisions: mir
+//[mir]compile-flags: -Z emit-end-regions -Z borrowck-mir
+
+struct Wrap<'p> { p: &'p mut i32 }
+
+impl<'p> Drop for Wrap<'p> {
+    fn drop(&mut self) {
+        *self.p += 1;
+    }
+}
+
+fn foo() {
+    let mut x = 0;
+    let wrap = Wrap { p: &mut x };
+    x += 1; //~ ERROR because of dtor
+}
+
+fn bar() {
+    let mut x = 0;
+    let wrap = Wrap { p: &mut x };
+    std::mem::drop(wrap);
+    x += 1; // OK, drop is inert
+}
+
+struct Foo<'p> { a: String, b: Wrap<'p> }
+
+fn move_string(_a: String) { }
+
+fn move_wrap<'p>(_b: Wrap<'p>) { }
+
+fn baz_a() {
+    let mut x = 0;
+    let wrap = Wrap { p: &mut x };
+    let s = String::from("str");
+    let foo = Foo { a: s, b: wrap };
+    move_string(foo.a);
+}
+
+fn baz_a_b() {
+    let mut x = 0;
+    let wrap = Wrap { p: &mut x };
+    let s = String::from("str");
+    let foo = Foo { a: s, b: wrap };
+    move_string(foo.a);
+    move_wrap(foo.b);
+}
+
+fn baz_b() {
+    let mut x = 0;
+    let wrap = Wrap { p: &mut x };
+    let s = String::from("str");
+    let foo = Foo { a: s, b: wrap };
+    move_wrap(foo.b);
+}
+
+fn main() { }

src/test/ui/nll/maybe-initialized-drop.stderr

@@ -0,0 +1,97 @@
+error[E0506]: cannot assign to `x` because it is borrowed (Ast)
+  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:24:5
+   |
+23 |     let wrap = Wrap { p: &mut x };
+   |                               - borrow of `x` occurs here
+24 |     x += 1; //~ ERROR because of dtor
+   |     ^^^^^^ assignment to borrowed `x` occurs here
+
+error[E0506]: cannot assign to `x` because it is borrowed (Ast)
+  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:31:5
+   |
+29 |     let wrap = Wrap { p: &mut x };
+   |                               - borrow of `x` occurs here
+30 |     std::mem::drop(wrap);
+31 |     x += 1; // OK, drop is inert
+   |     ^^^^^^ assignment to borrowed `x` occurs here
+
+error[E0506]: cannot assign to `x` because it is borrowed (Mir)
+  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:24:5
+   |
+23 |     let wrap = Wrap { p: &mut x };
+   |                          ------ borrow of `x` occurs here
+24 |     x += 1; //~ ERROR because of dtor
+   |     ^^^^^^ assignment to borrowed `x` occurs here
+
+error[E0503]: cannot use `x` because it was mutably borrowed (Mir)
+  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:24:5
+   |
+23 |     let wrap = Wrap { p: &mut x };
+   |                          ------ borrow of `x` occurs here
+24 |     x += 1; //~ ERROR because of dtor
+   |     ^^^^^^ use of borrowed `x`
+
+error[E0506]: cannot assign to `x` because it is borrowed (Mir)
+  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:25:2
+   |
+23 |     let wrap = Wrap { p: &mut x };
+   |                          ------ borrow of `x` occurs here
+24 |     x += 1; //~ ERROR because of dtor
+25 | }
+   |  ^ assignment to borrowed `x` occurs here
+
+error[E0506]: cannot assign to `x` because it is borrowed (Mir)
+  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:31:5
+   |
+29 |     let wrap = Wrap { p: &mut x };
+   |                          ------ borrow of `x` occurs here
+30 |     std::mem::drop(wrap);
+31 |     x += 1; // OK, drop is inert
+   |     ^^^^^^ assignment to borrowed `x` occurs here
+
+error[E0503]: cannot use `x` because it was mutably borrowed (Mir)
+  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:31:5
+   |
+29 |     let wrap = Wrap { p: &mut x };
+   |                          ------ borrow of `x` occurs here
+30 |     std::mem::drop(wrap);
+31 |     x += 1; // OK, drop is inert
+   |     ^^^^^^ use of borrowed `x`
+
+error[E0506]: cannot assign to `x` because it is borrowed (Mir)
+  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:32:2
+   |
+29 |     let wrap = Wrap { p: &mut x };
+   |                          ------ borrow of `x` occurs here
+...
+32 | }
+   |  ^ assignment to borrowed `x` occurs here
+
+error[E0506]: cannot assign to `x` because it is borrowed (Mir)
+  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:46:2
+   |
+42 |     let wrap = Wrap { p: &mut x };
+   |                          ------ borrow of `x` occurs here
+...
+46 | }
+   |  ^ assignment to borrowed `x` occurs here
+
+error[E0506]: cannot assign to `x` because it is borrowed (Mir)
+  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:55:2
+   |
+50 |     let wrap = Wrap { p: &mut x };
+   |                          ------ borrow of `x` occurs here
+...
+55 | }
+   |  ^ assignment to borrowed `x` occurs here
+
+error[E0506]: cannot assign to `x` because it is borrowed (Mir)
+  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:63:2
+   |
+59 |     let wrap = Wrap { p: &mut x };
+   |                          ------ borrow of `x` occurs here
+...
+63 | }
+   |  ^ assignment to borrowed `x` occurs here
+
+error: aborting due to 11 previous errors