Merge ref '6bcdcc73bd11' from rust-lang/rust

Pull recent changes from https://github.com/rust-lang/rust via Josh.

Upstream ref: 6bcdcc73bd11568fd85f5a38b58e1eda054ad1cd
Filtered ref: 6cc4ce79e1f8dc0ec5a2e18049b9c1a51dee3221

This merge was created using https://github.com/rust-lang/josh-sync.

3 files changed, 133 insertions, 0 deletions

diff --git a/tests/ui/drop/destructor-run-for-expression-4734.rs b/tests/ui/drop/destructor-run-for-expression-4734.rs
new file mode 100644
index 00000000000..57971ee5ef7
--- /dev/null
+++ b/tests/ui/drop/destructor-run-for-expression-4734.rs
@@ -0,0 +1,39 @@
+// https://github.com/rust-lang/rust/issues/4734
+//@ run-pass
+#![allow(dead_code)]
+// Ensures that destructors are run for expressions of the form "e;" where
+// `e` is a type which requires a destructor.
+
+// FIXME(static_mut_refs): Do not allow `static_mut_refs` lint
+#![allow(static_mut_refs)]
+#![allow(path_statements)]
+
+struct A { n: isize }
+struct B;
+
+static mut NUM_DROPS: usize = 0;
+
+impl Drop for A {
+    fn drop(&mut self) {
+        unsafe { NUM_DROPS += 1; }
+    }
+}
+
+impl Drop for B {
+    fn drop(&mut self) {
+        unsafe { NUM_DROPS += 1; }
+    }
+}
+
+fn main() {
+    assert_eq!(unsafe { NUM_DROPS }, 0);
+    { let _a = A { n: 1 }; }
+    assert_eq!(unsafe { NUM_DROPS }, 1);
+    { A { n: 3 }; }
+    assert_eq!(unsafe { NUM_DROPS }, 2);
+
+    { let _b = B; }
+    assert_eq!(unsafe { NUM_DROPS }, 3);
+    { B; }
+    assert_eq!(unsafe { NUM_DROPS }, 4);
+}
diff --git a/tests/ui/drop/destructor-run-for-let-ignore-6892.rs b/tests/ui/drop/destructor-run-for-let-ignore-6892.rs
new file mode 100644
index 00000000000..0fcf133c2b1
--- /dev/null
+++ b/tests/ui/drop/destructor-run-for-let-ignore-6892.rs
@@ -0,0 +1,61 @@
+// https://github.com/rust-lang/rust/issues/6892
+//@ run-pass
+#![allow(dead_code)]
+// Ensures that destructors are run for expressions of the form "let _ = e;"
+// where `e` is a type which requires a destructor.
+
+// FIXME(static_mut_refs): Do not allow `static_mut_refs` lint
+#![allow(static_mut_refs)]
+
+struct Foo;
+struct Bar { x: isize }
+struct Baz(isize);
+enum FooBar { _Foo(Foo), _Bar(usize) }
+
+static mut NUM_DROPS: usize = 0;
+
+impl Drop for Foo {
+    fn drop(&mut self) {
+        unsafe { NUM_DROPS += 1; }
+    }
+}
+impl Drop for Bar {
+    fn drop(&mut self) {
+        unsafe { NUM_DROPS += 1; }
+    }
+}
+impl Drop for Baz {
+    fn drop(&mut self) {
+        unsafe { NUM_DROPS += 1; }
+    }
+}
+impl Drop for FooBar {
+    fn drop(&mut self) {
+        unsafe { NUM_DROPS += 1; }
+    }
+}
+
+fn main() {
+    assert_eq!(unsafe { NUM_DROPS }, 0);
+    { let _x = Foo; }
+    assert_eq!(unsafe { NUM_DROPS }, 1);
+    { let _x = Bar { x: 21 }; }
+    assert_eq!(unsafe { NUM_DROPS }, 2);
+    { let _x = Baz(21); }
+    assert_eq!(unsafe { NUM_DROPS }, 3);
+    { let _x = FooBar::_Foo(Foo); }
+    assert_eq!(unsafe { NUM_DROPS }, 5);
+    { let _x = FooBar::_Bar(42); }
+    assert_eq!(unsafe { NUM_DROPS }, 6);
+
+    { let _ = Foo; }
+    assert_eq!(unsafe { NUM_DROPS }, 7);
+    { let _ = Bar { x: 21 }; }
+    assert_eq!(unsafe { NUM_DROPS }, 8);
+    { let _ = Baz(21); }
+    assert_eq!(unsafe { NUM_DROPS }, 9);
+    { let _ = FooBar::_Foo(Foo); }
+    assert_eq!(unsafe { NUM_DROPS }, 11);
+    { let _ = FooBar::_Bar(42); }
+    assert_eq!(unsafe { NUM_DROPS }, 12);
+}
diff --git a/tests/ui/drop/drop-count-assertion-16151.rs b/tests/ui/drop/drop-count-assertion-16151.rs
new file mode 100644
index 00000000000..ede6bc23e73
--- /dev/null
+++ b/tests/ui/drop/drop-count-assertion-16151.rs
@@ -0,0 +1,33 @@
+// https://github.com/rust-lang/rust/issues/16151
+//@ run-pass
+
+// FIXME(static_mut_refs): Do not allow `static_mut_refs` lint
+#![allow(static_mut_refs)]
+
+use std::mem;
+
+static mut DROP_COUNT: usize = 0;
+
+struct Fragment;
+
+impl Drop for Fragment {
+    fn drop(&mut self) {
+        unsafe {
+            DROP_COUNT += 1;
+        }
+    }
+}
+
+fn main() {
+    {
+        let mut fragments = vec![Fragment, Fragment, Fragment];
+        let _new_fragments: Vec<Fragment> = mem::replace(&mut fragments, vec![])
+            .into_iter()
+            .skip_while(|_fragment| {
+                true
+            }).collect();
+    }
+    unsafe {
+        assert_eq!(DROP_COUNT, 3);
+    }
+}