) {
// If the `'a` region is bound within the field type itself, we
// don't want to propagate this constraint to the header.
- if !is_free_region(outlived_region) {
+ if !is_free_region(tcx, outlived_region) {
return;
}
}
UnpackedKind::Lifetime(r) => {
- if !is_free_region(r) {
+ if !is_free_region(tcx, r) {
return;
}
required_predicates.insert(ty::OutlivesPredicate(kind, outlived_region));
}
}
-fn is_free_region(region: Region<'_>) -> bool {
+fn is_free_region<'tcx>(tcx: TyCtxt<'_, 'tcx, 'tcx>, region: Region<'_>) -> bool {
// First, screen for regions that might appear in a type header.
match region {
- // *These* correspond to `T: 'a` relationships where `'a` is
- // either declared on the type or `'static`:
+ // These correspond to `T: 'a` relationships:
//
// struct Foo<'a, T> {
// field: &'a T, // this would generate a ReEarlyBound referencing `'a`
- // field2: &'static T, // this would generate a ReStatic
// }
//
// We care about these, so fall through.
- RegionKind::ReStatic | RegionKind::ReEarlyBound(_) => true,
+ RegionKind::ReEarlyBound(_) => true,
+
+ // These correspond to `T: 'static` relationships which can be
+ // rather surprising. We are therefore putting this behind a
+ // feature flag:
+ //
+ // struct Foo<'a, T> {
+ // field: &'static T, // this would generate a ReStatic
+ // }
+ RegionKind::ReStatic => {
+ if tcx
+ .sess
+ .features_untracked()
+ .infer_static_outlives_requirements
+ {
+ true
+ } else {
+ false
+ }
+ }
// Late-bound regions can appear in `fn` types:
//
// Infer outlives requirements; RFC 2093
(active, infer_outlives_requirements, "1.26.0", Some(44493), None),
+ // Infer outlives requirements; RFC 2093
+ (active, infer_static_outlives_requirements, "1.26.0", Some(44493), None),
+
// Multiple patterns with `|` in `if let` and `while let`
(active, if_while_or_patterns, "1.26.0", Some(48215), None),
"infer outlives requirements is an experimental feature",
cfg_fn!(infer_outlives_requirements))),
+ // RFC #2093
+ ("infer_static_outlives_requirements", Normal, Gated(Stability::Unstable,
+ "infer_static_outlives_requirements",
+ "infer 'static lifetime requirements",
+ cfg_fn!(infer_static_outlives_requirements))),
+
// RFC 2070
("panic_implementation", Normal, Gated(Stability::Unstable,
"panic_implementation",
--- /dev/null
+// 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.
+
+// ignore-tidy-linelength
+
+#![feature(infer_outlives_requirements)]
+
+struct Foo<U> {
+ bar: Bar<U> //~ ERROR 16:5: 16:16: the parameter type `U` may not live long enough [E0310]
+}
+struct Bar<T: 'static> {
+ x: T,
+}
+
+fn main() {}
+
--- /dev/null
+error[E0310]: the parameter type `U` may not live long enough
+ --> $DIR/dont-infer-static.rs:16:5
+ |
+LL | struct Foo<U> {
+ | - help: consider adding an explicit lifetime bound `U: 'static`...
+LL | bar: Bar<U> //~ ERROR 16:5: 16:16: the parameter type `U` may not live long enough [E0310]
+ | ^^^^^^^^^^^
+ |
+note: ...so that the type `U` will meet its required lifetime bounds
+ --> $DIR/dont-infer-static.rs:16:5
+ |
+LL | bar: Bar<U> //~ ERROR 16:5: 16:16: the parameter type `U` may not live long enough [E0310]
+ | ^^^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0310`.
--- /dev/null
+// 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.
+
+#![feature(rustc_attrs)]
+#![feature(infer_outlives_requirements)]
+#![feature(infer_static_outlives_requirements)]
+
+#[rustc_outlives]
+struct Foo<U> { //~ ERROR 16:1: 18:2: rustc_outlives
+ bar: Bar<U>
+}
+struct Bar<T: 'static> {
+ x: T,
+}
+
+fn main() {}
+
+
--- /dev/null
+error: rustc_outlives
+ --> $DIR/infer-static.rs:16:1
+ |
+LL | / struct Foo<U> { //~ ERROR 16:1: 18:2: rustc_outlives
+LL | | bar: Bar<U>
+LL | | }
+ | |_^
+ |
+ = note: U : 'static
+
+error: aborting due to previous error
+