Add more tests for impl Trait lifetime handling

Author: cramertj

src/test/compile-fail/impl-trait/lifetimes.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.
+
+#![feature(conservative_impl_trait)]
+
+use std::fmt::Debug;
+
+fn elided(x: &i32) -> impl Copy { x }
+//~^ ERROR cannot infer an appropriate lifetime
+
+fn explicit<'a>(x: &'a i32) -> impl Copy { x }
+//~^ ERROR cannot infer an appropriate lifetime
+
+trait LifetimeTrait<'a> {}
+impl<'a> LifetimeTrait<'a> for &'a i32 {}
+
+fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
+//~^ ERROR cannot infer an appropriate lifetime
+
+// Tests that a closure type contianing 'b cannot be returned from a type where
+// only 'a was expected.
+fn move_lifetime_into_fn<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Fn(&'a u32) {
+    //~^ ERROR lifetime mismatch
+    move |_| println!("{}", y)
+}
+
+fn main() {}

src/test/compile-fail/impl-trait/must_outlive_least_region_or_bound.rs

@@ -0,0 +1,23 @@
+// 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.
+
+#![feature(conservative_impl_trait)]
+
+use std::fmt::Debug;
+
+trait MultiRegionTrait<'a, 'b> {}
+impl<'a, 'b> MultiRegionTrait<'a, 'b> for (&'a u32, &'b u32) {}
+
+fn no_least_region<'a, 'b>(x: &'a u32, y: &'b u32) -> impl MultiRegionTrait<'a, 'b> {
+//~^ ERROR ambiguous lifetime bound
+    (x, y)
+}
+
+fn main() {}

src/test/compile-fail/impl-trait/needs_least_region_or_bound.rs

@@ -16,14 +16,9 @@ trait Any {}
 impl<T> Any for T {}
 
 // Check that type parameters are captured and not considered 'static
-fn whatever<T>(x: T) -> impl Any + 'static {
+fn foo<T>(x: T) -> impl Any + 'static {
     //~^ ERROR the parameter type `T` may not live long enough
     x
 }
 
-fn move_lifetime_into_fn<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Fn(&'a u32) {
-    //~^ ERROR lifetime mismatch
-    move |_| println!("{}", y)
-}
-
 fn main() {}

src/test/compile-fail/impl-trait/more_lifetimes.rs renamed to src/test/compile-fail/impl-trait/type_parameters_captured.rs

@@ -25,29 +25,57 @@ fn lifetimes_as_static_impl_trait() -> impl Debug {
         static_lifetime()
 }
 
-trait Foo<'a> {}
-impl<'a> Foo<'a> for u32 {}
-
-fn foo<'b>() -> impl for<'a> Foo<'a> { 5 }
+trait SingleRegionTrait<'a> {}
+impl<'a> SingleRegionTrait<'a> for u32 {}
 
+fn simple_type_hrtb<'b>() -> impl for<'a> SingleRegionTrait<'a> { 5 }
 fn closure_hrtb() -> impl for<'a> Fn(&'a u32) { |_| () }
 
 fn mixed_lifetimes<'a>() -> impl for<'b: 'a> Fn(&'b u32) { |_| () }
-
 fn mixed_as_static() -> impl Fn(&'static u32) { mixed_lifetimes() }
 
-trait MultiRegion<'a, 'b> {}
+trait MultiRegionTrait<'a, 'b>: Debug {}
+
+#[derive(Debug)]
 struct MultiRegionStruct<'a, 'b>(&'a u32, &'b u32);
-impl<'a, 'b> MultiRegion<'a, 'b> for MultiRegionStruct<'a, 'b> {}
+impl<'a, 'b> MultiRegionTrait<'a, 'b> for MultiRegionStruct<'a, 'b> {}
 
-fn finds_least_region<'a: 'b, 'b>(x: &'a u32, y: &'b u32) -> impl MultiRegion<'a, 'b>
-{
+#[derive(Debug)]
+struct NoRegionStruct;
+impl<'a, 'b> MultiRegionTrait<'a, 'b> for NoRegionStruct {}
+
+fn finds_least_region<'a: 'b, 'b>(x: &'a u32, y: &'b u32) -> impl MultiRegionTrait<'a, 'b> {
     MultiRegionStruct(x, y)
 }
 
-fn explicit_bound<'a: 'b, 'b>(x: &'a u32, y: &'b u32) -> impl MultiRegion<'a, 'b> + 'b
+fn finds_explicit_bound<'a: 'b, 'b>
+    (x: &'a u32, y: &'b u32) -> impl MultiRegionTrait<'a, 'b> + 'b
 {
     MultiRegionStruct(x, y)
 }
 
+fn finds_explicit_bound_even_without_least_region<'a, 'b>
+    (x: &'a u32, y: &'b u32) -> impl MultiRegionTrait<'a, 'b> + 'b
+{
+    NoRegionStruct
+}
+
+/* FIXME: `impl Trait<'a> + 'b` should live as long as 'b, even if 'b outlives 'a
+fn outlives_bounds_even_with_contained_regions<'a, 'b>
+    (x: &'a u32, y: &'b u32) -> impl Debug + 'b
+{
+    finds_explicit_bound_even_without_least_region(x, y)
+}
+*/
+
+fn unnamed_lifetimes_arent_contained_in_impl_trait_and_will_unify<'a, 'b>
+    (x: &'a u32, y: &'b u32) -> impl Debug
+{
+    fn deref<'lt>(x: &'lt u32) -> impl Debug { *x }
+
+    if true { deref(x) } else { deref(y) }
+}
+
+fn can_add_region_bound_to_static_type<'a, 'b>(_: &'a u32) -> impl Debug + 'a { 5 }
+
 fn main() {}