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Auto merge of #36332 - llogiq:static_consts_feature, r=nikomatsakis

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add static_in_const feature gate

also updates tests and deletes the spurious .bk files I inadvertently added last time.

r? @nikomatsakis
This commit is contained in:
bors 2016-09-09 21:35:30 -07:00 • committed by GitHub
commit f508ddc547
10 changed files with 62 additions and 182 deletions
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3
src/doc/reference.md
View file

@ -2441,6 +2441,9 @@ The currently implemented features of the reference compiler are:
into a Rust program. This capability, especially the signature for the
annotated function, is subject to change.
* `static_in_const` - Enables lifetime elision with a `'static` default for
`const` and `static` item declarations.
* `thread_local` - The usage of the `#[thread_local]` attribute is experimental
and should be seen as unstable. This attribute is used to
declare a `static` as being unique per-thread leveraging

2
src/librustc_typeck/collect.rs
View file

@ -1567,7 +1567,7 @@ fn type_of_def_id<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
NodeItem(item) => {
match item.node {
ItemStatic(ref t, ..) | ItemConst(ref t, _) => {
ccx.icx(&()).to_ty(&ElidableRscope::new(ty::ReStatic), &t)
ccx.icx(&()).to_ty(&StaticRscope::new(&ccx.tcx), &t)
}
ItemFn(ref decl, unsafety, _, abi, ref generics, _) => {
let tofd = AstConv::ty_of_bare_fn(&ccx.icx(generics), unsafety, abi, &decl,

39
src/librustc_typeck/rscope.rs
View file

@ -213,6 +213,45 @@ impl RegionScope for ElidableRscope {
}
}
/// A scope that behaves as an ElidabeRscope with a `'static` default region
/// that should also warn if the `static_in_const` feature is unset.
#[derive(Copy, Clone)]
pub struct StaticRscope<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
tcx: &'a ty::TyCtxt<'a, 'gcx, 'tcx>,
}
impl<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> StaticRscope<'a, 'gcx, 'tcx> {
/// create a new StaticRscope from a reference to the `TyCtxt`
pub fn new(tcx: &'a ty::TyCtxt<'a, 'gcx, 'tcx>) -> Self {
StaticRscope { tcx: tcx }
}
}
impl<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> RegionScope for StaticRscope<'a, 'gcx, 'tcx> {
fn anon_regions(&self,
span: Span,
count: usize)
-> Result<Vec<ty::Region>, Option<Vec<ElisionFailureInfo>>> {
if !self.tcx.sess.features.borrow().static_in_const {
self.tcx
.sess
.struct_span_err(span,
"this needs a `'static` lifetime or the \
`static_in_const` feature, see #35897")
.emit();
}
Ok(vec![ty::ReStatic; count])
}
fn object_lifetime_default(&self, span: Span) -> Option<ty::Region> {
Some(self.base_object_lifetime_default(span))
}
fn base_object_lifetime_default(&self, _span: Span) -> ty::Region {
ty::ReStatic
}
}
/// A scope in which we generate anonymous, late-bound regions for
/// omitted regions. This occurs in function signatures.
pub struct BindingRscope {

3
src/libsyntax/feature_gate.rs
View file

@ -295,6 +295,9 @@ declare_features! (
// Allows untagged unions `union U { ... }`
(active, untagged_unions, "1.13.0", Some(32836)),
// elide `'static` lifetimes in `static`s and `const`s
(active, static_in_const, "1.13.0", Some(35897)),
);
declare_features! (

14
src/test/compile-fail/feature-gate-static-in-const.rs Normal file
View file

@ -0,0 +1,14 @@
// 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.
static FOO: &str = "this will work once static_in_const is stable";
//~^ ERROR: this needs a `'static` lifetime or the `static_in_const` feature
fn main() {}

1
src/test/compile-fail/issue-24446.rs
View file

@ -12,7 +12,6 @@ fn main() {
static foo: Fn() -> u32 = || -> u32 {
//~^ ERROR: mismatched types
//~| ERROR: `std::ops::Fn() -> u32 + 'static: std::marker::Sized` is not satisfied
0
};
}

2
src/test/compile-fail/rfc1623.rs
View file

@ -7,7 +7,7 @@
// <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(static_in_const)]
#![allow(dead_code)]
fn non_elidable<'a, 'b>(a: &'a u8, b: &'b u8) -> &'a u8 {

98
src/test/compile-fail/rfc1623.rs.bk
View file

@ -1,98 +0,0 @@
// 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 <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.
#![allow(dead_code)]
fn non_elidable<'a, 'b>(a: &'a u8, b: &'b u8) -> &'a u8 { a }
// the boundaries of elision
static NON_ELIDABLE_FN : &fn(&u8, &u8) -> &u8 =
//~^ ERROR: missing lifetime specifier
&(non_elidable as fn(&u8, &u8) -> &u8);
struct SomeStruct<'x, 'y, 'z: 'x> {
foo: &'x Foo<'z>,
bar: &'x Bar<'z>,
f: &'y for<'a, 'b: 'a> Fn(&'a Foo<'b>) -> &'a Bar<'b>,
}
fn id<T>(t: T) -> T { t }
static SOME_STRUCT : &SomeStruct = SomeStruct {
foo: &Foo { bools: &[false, true] },
bar: &Bar { bools: &[true, true] },
f: &id,
};
// very simple test for a 'static static with default lifetime
static STATIC_STR : &'static str = "&'static str";
const CONST_STR : &'static str = "&'static str";
// this should be the same as without default:
static EXPLICIT_STATIC_STR : &'static str = "&'static str";
const EXPLICIT_CONST_STR : &'static str = "&'static str";
// a function that elides to an unbound lifetime for both in- and output
fn id_u8_slice(arg: &[u8]) -> &[u8] { arg }
// one with a function, argument elided
static STATIC_SIMPLE_FN : &'static fn(&[u8]) -> &[u8] =
&(id_u8_slice as fn(&[u8]) -> &[u8]);
const CONST_SIMPLE_FN : &'static fn(&[u8]) -> &[u8] =
&(id_u8_slice as fn(&[u8]) -> &[u8]);
// this should be the same as without elision
static STATIC_NON_ELIDED_fN : &'static for<'a> fn(&'a [u8]) -> &'a [u8] =
&(id_u8_slice as for<'a> fn(&'a [u8]) -> &'a [u8]);
const CONST_NON_ELIDED_fN : &'static for<'a> fn(&'a [u8]) -> &'a [u8] =
&(id_u8_slice as for<'a> fn(&'a [u8]) -> &'a [u8]);
// another function that elides, each to a different unbound lifetime
fn multi_args(a: &u8, b: &u8, c: &u8) { }
static STATIC_MULTI_FN : &'static fn(&u8, &u8, &u8) =
&(multi_args as fn(&u8, &u8, &u8));
const CONST_MULTI_FN : &'static fn(&u8, &u8, &u8) =
&(multi_args as fn(&u8, &u8, &u8));
struct Foo<'a> {
bools: &'a [bool]
}
static STATIC_FOO : Foo<'static> = Foo { bools: &[true, false] };
const CONST_FOO : Foo<'static> = Foo { bools: &[true, false] };
type Bar<'a> = Foo<'a>;
static STATIC_BAR : Bar<'static> = Bar { bools: &[true, false] };
const CONST_BAR : Bar<'static> = Bar { bools: &[true, false] };
type Baz<'a> = fn(&'a [u8]) -> Option<u8>;
fn baz(e: &[u8]) -> Option<u8> { e.first().map(|x| *x) }
static STATIC_BAZ : &'static Baz<'static> = &(baz as Baz);
const CONST_BAZ : &'static Baz<'static> = &(baz as Baz);
static BYTES : &'static [u8] = &[1, 2, 3];
fn main() {
let x = &[1u8, 2, 3];
let y = x;
//this works, so lifetime < `'static` is valid
assert_eq!(Some(1), STATIC_BAZ(y));
assert_eq!(Some(1), CONST_BAZ(y));
let y = &[1u8, 2, 3];
//^~ ERROR: borrowed values does not live long enough
STATIC_BAZ(BYTES); // BYTES has static lifetime
CONST_BAZ(y); // This forces static lifetime, which y has not
}

1
src/test/run-pass/rfc1623.rs
View file

@ -8,6 +8,7 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#![feature(static_in_const)]
#![allow(dead_code)]
// very simple test for a 'static static with default lifetime

81
src/test/run-pass/rfc1623.rs.bk
View file

@ -1,81 +0,0 @@
// 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 <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.
#![allow(dead_code)]
// very simple test for a 'static static with default lifetime
static STATIC_STR : &str = "&'static str";
const CONST_STR : &str = "&'static str";
// this should be the same as without default:
static EXPLICIT_STATIC_STR : &'static str = "&'static str";
const EXPLICIT_CONST_STR : &'static str = "&'static str";
// a function that elides to an unbound lifetime for both in- and output
fn id_u8_slice(arg: &[u8]) -> &[u8] { arg }
// one with a function, argument elided
static STATIC_SIMPLE_FN : &fn(&[u8]) -> &[u8] =
&(id_u8_slice as fn(&[u8]) -> &[u8]);
const CONST_SIMPLE_FN : &fn(&[u8]) -> &[u8] =
&(id_u8_slice as fn(&[u8]) -> &[u8]);
// this should be the same as without elision
static STATIC_NON_ELIDED_fN : &for<'a> fn(&'a [u8]) -> &'a [u8] =
&(id_u8_slice as for<'a> fn(&'a [u8]) -> &'a [u8]);
const CONST_NON_ELIDED_fN : &for<'a> fn(&'a [u8]) -> &'a [u8] =
&(id_u8_slice as for<'a> fn(&'a [u8]) -> &'a [u8]);
// another function that elides, each to a different unbound lifetime
fn multi_args(a: &u8, b: &u8, c: &u8) { }
static STATIC_MULTI_FN : &fn(&u8, &u8, &u8) =
&(multi_args as fn(&u8, &u8, &u8));
const CONST_MULTI_FN : &fn(&u8, &u8, &u8) =
&(multi_args as fn(&u8, &u8, &u8));
struct Foo<'a> {
bools: &'a [bool]
}
static STATIC_FOO : Foo = Foo { bools: &[true, false] };
const CONST_FOO : Foo = Foo { bools: &[true, false] };
type Bar<'a> = Foo<'a>;
static STATIC_BAR : Bar = Bar { bools: &[true, false] };
const CONST_BAR : Bar = Bar { bools: &[true, false] };
type Baz<'a> = fn(&'a [u8]) -> Option<u8>;
fn baz(e: &[u8]) -> Option<u8> { e.first().map(|x| *x) }
static STATIC_BAZ : &Baz = &(baz as Baz);
const CONST_BAZ : &Baz = &(baz as Baz);
static BYTES : &[u8] = &[1, 2, 3];
fn main() {
// make sure that the lifetime is actually elided (and not defaulted)
let x = &[1u8, 2, 3];
STATIC_SIMPLE_FN(x);
CONST_SIMPLE_FN(x);
STATIC_BAZ(BYTES); // neees static lifetime
CONST_BAZ(BYTES);
// make sure this works with different lifetimes
let a = &1;
{
let b = &2;
let c = &3;
CONST_MULTI_FN(a, b, c);
}
}