add regression tests for various MIR bugs that get fixed

Fixes #31567
Fixes #47470
Fixes #48132
Fixes #48179

Author: nikomatsakis

src/test/ui/issue-48132.rs

@@ -0,0 +1,42 @@
+// Copyright 2015 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.
+
+// Regression test for #48132. This was failing due to problems around
+// the projection caching and dropck type enumeration.
+
+// run-pass
+
+#![feature(nll)]
+#![allow(warnings)]
+
+struct Inner<I, V> {
+    iterator: I,
+    item: V,
+}
+
+struct Outer<I: Iterator> {
+    inner: Inner<I, I::Item>,
+}
+
+fn outer<I>(iterator: I) -> Outer<I>
+where I: Iterator,
+      I::Item: Default,
+{
+    Outer {
+        inner: Inner {
+            iterator: iterator,
+            item: Default::default(),
+        }
+    }
+}
+
+fn main() {
+    outer(std::iter::once(&1).cloned());
+}

src/test/ui/issue-48179.rs

@@ -0,0 +1,51 @@
+// Copyright 2015 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.
+
+// Regression test for #48132. This was failing due to problems around
+// the projection caching and dropck type enumeration.
+
+// run-pass
+
+#![feature(nll)]
+#![allow(warnings)]
+
+pub struct Container<T: Iterator> {
+    value: Option<T::Item>,
+}
+
+impl<T: Iterator> Container<T> {
+    pub fn new(iter: T) -> Self {
+        panic!()
+    }
+}
+
+pub struct Wrapper<'a> {
+    content: &'a Content,
+}
+
+impl<'a, 'de> Wrapper<'a> {
+    pub fn new(content: &'a Content) -> Self {
+        Wrapper {
+            content: content,
+        }
+    }
+}
+
+pub struct Content;
+
+fn crash_it(content: Content) {
+    let items = vec![content];
+    let map = items.iter().map(|ref o| Wrapper::new(o));
+
+    let mut map_visitor = Container::new(map);
+
+}
+
+fn main() {}

src/test/ui/nll/issue-31567.rs

@@ -0,0 +1,37 @@
+// 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.
+
+// Regression test for #31567: cached results of projections were
+// causing region relations not to be enforced at all the places where
+// they have to be enforced.
+
+#![feature(nll)]
+
+struct VecWrapper<'a>(&'a mut S);
+
+struct S(Box<u32>);
+
+fn get_dangling<'a>(v: VecWrapper<'a>) -> &'a u32 {
+    let s_inner: &'a S = &*v.0; //~ ERROR `*v.0` does not live long enough
+    &s_inner.0
+}
+
+impl<'a> Drop for VecWrapper<'a> {
+    fn drop(&mut self) {
+        *self.0 = S(Box::new(0));
+    }
+}
+
+fn main() {
+    let mut s = S(Box::new(11));
+    let vw = VecWrapper(&mut s);
+    let dangling = get_dangling(vw);
+    println!("{}", dangling);
+}

src/test/ui/nll/issue-31567.stderr

@@ -0,0 +1,18 @@
+error[E0597]: `*v.0` does not live long enough
+  --> $DIR/issue-31567.rs:22:26
+   |
+LL |     let s_inner: &'a S = &*v.0; //~ ERROR `*v.0` does not live long enough
+   |                          ^^^^^ borrowed value does not live long enough
+LL |     &s_inner.0
+LL | }
+   | - borrowed value only lives until here
+   |
+note: borrowed value must be valid for the lifetime 'a as defined on the function body at 21:1...
+  --> $DIR/issue-31567.rs:21:1
+   |
+LL | fn get_dangling<'a>(v: VecWrapper<'a>) -> &'a u32 {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
+If you want more information on this error, try using "rustc --explain E0597"

src/test/ui/nll/issue-47470.rs

@@ -0,0 +1,34 @@
+// 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.
+
+// Regression test for #47470: cached results of projections were
+// causing region relations not to be enforced at all the places where
+// they have to be enforced.
+
+#![feature(nll)]
+
+struct Foo<'a>(&'a ());
+trait Bar {
+    type Assoc;
+    fn get(self) -> Self::Assoc;
+}
+
+impl<'a> Bar for Foo<'a> {
+    type Assoc = &'a u32;
+    fn get(self) -> Self::Assoc {
+        let local = 42;
+        &local //~ ERROR `local` does not live long enough
+    }
+}
+
+fn main() {
+    let f = Foo(&()).get();
+    println!("{}", f);
+}

src/test/ui/nll/issue-47470.stderr

@@ -0,0 +1,17 @@
+error[E0597]: `local` does not live long enough
+  --> $DIR/issue-47470.rs:27:9
+   |
+LL |         &local //~ ERROR `local` does not live long enough
+   |         ^^^^^^ borrowed value does not live long enough
+LL |     }
+   |     - borrowed value only lives until here
+   |
+note: borrowed value must be valid for the lifetime 'a as defined on the impl at 23:1...
+  --> $DIR/issue-47470.rs:23:1
+   |
+LL | impl<'a> Bar for Foo<'a> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
+If you want more information on this error, try using "rustc --explain E0597"