diff --git a/src/librustc/middle/typeck/infer/region_inference/mod.rs b/src/librustc/middle/typeck/infer/region_inference/mod.rs index bb6d479870b91..5afbb48ca3ca6 100644 --- a/src/librustc/middle/typeck/infer/region_inference/mod.rs +++ b/src/librustc/middle/typeck/infer/region_inference/mod.rs @@ -299,6 +299,9 @@ impl<'a> RegionVarBindings<'a> { sub.repr(self.tcx), sup.repr(self.tcx))); } + (_, ReStatic) => { + // all regions are subregions of static, so we can ignore this + } (ReInfer(ReVar(sub_id)), ReInfer(ReVar(sup_id))) => { self.add_constraint(ConstrainVarSubVar(sub_id, sup_id), origin); } diff --git a/src/test/compile-fail/regions-fn-subtyping-return-static.rs b/src/test/compile-fail/regions-fn-subtyping-return-static.rs new file mode 100644 index 0000000000000..c03040fe0f211 --- /dev/null +++ b/src/test/compile-fail/regions-fn-subtyping-return-static.rs @@ -0,0 +1,60 @@ +// Copyright 2012 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 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +// In this fn, the type `F` is a function that takes a reference to a +// struct and returns another reference with the same lifetime. +// +// Meanwhile, the bare fn `foo` takes a reference to a struct with +// *ANY* lifetime and returns a reference with the 'static lifetime. +// This can safely be considered to be an instance of `F` because all +// lifetimes are sublifetimes of 'static. + +#![allow(dead_code)] +#![allow(unused_variable)] + +struct S; + +// Given 'cx, return 'cx +type F = fn<'cx>(&'cx S) -> &'cx S; +fn want_F(f: F) { } + +// Given anything, return 'static +type G = fn<'cx>(&'cx S) -> &'static S; +fn want_G(f: G) { } + +// Should meet both. +fn foo(x: &S) -> &'static S { + fail!() +} + +// Should meet both. +fn bar<'a,'b>(x: &'a S) -> &'b S { + fail!() +} + +// Meets F, but not G. +fn baz<'a>(x: &'a S) -> &'a S { + fail!() +} + +fn supply_F() { + want_F(foo); + want_F(bar); + want_F(baz); +} + +fn supply_G() { + want_G(foo); + want_G(bar); + want_G(baz); //~ ERROR expected concrete lifetime +} + +pub fn main() { +}