Auto merge of #44551 - scalexm:copy-clone-closures, r=arielb1

Implement `Copy`/`Clone` for closures

Implement RFC [#2132](https://github.com/rust-lang/rfcs/pull/2132) (tracking issue: #44490).

NB: I'm not totally sure about the whole feature gates thing, that's my first PR of this kind...
This commit is contained in:
bors 2017-09-21 00:35:33 +00:00
commit e2504cfc76
17 changed files with 264 additions and 18 deletions

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@ -570,6 +570,8 @@ define_dep_nodes!( <'tcx>
[] MissingExternCrateItem(CrateNum),
[] UsedCrateSource(CrateNum),
[] PostorderCnums,
[] HasCloneClosures(CrateNum),
[] HasCopyClosures(CrateNum),
[] Freevars(DefId),
[] MaybeUnusedTraitImport(DefId),

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@ -1340,7 +1340,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
self.assemble_candidates_from_impls(obligation, &mut candidates)?;
// For other types, we'll use the builtin rules.
let copy_conditions = self.copy_conditions(obligation);
let copy_conditions = self.copy_clone_conditions(obligation);
self.assemble_builtin_bound_candidates(copy_conditions, &mut candidates)?;
} else if lang_items.sized_trait() == Some(def_id) {
// Sized is never implementable by end-users, it is
@ -1355,7 +1355,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
// Same builtin conditions as `Copy`, i.e. every type which has builtin support
// for `Copy` also has builtin support for `Clone`, + tuples and arrays of `Clone`
// types have builtin support for `Clone`.
let clone_conditions = self.copy_conditions(obligation);
let clone_conditions = self.copy_clone_conditions(obligation);
self.assemble_builtin_bound_candidates(clone_conditions, &mut candidates)?;
}
@ -2050,7 +2050,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
}
}
fn copy_conditions(&mut self, obligation: &TraitObligation<'tcx>)
fn copy_clone_conditions(&mut self, obligation: &TraitObligation<'tcx>)
-> BuiltinImplConditions<'tcx>
{
// NOTE: binder moved to (*)
@ -2068,8 +2068,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
Where(ty::Binder(Vec::new()))
}
ty::TyDynamic(..) | ty::TyStr | ty::TySlice(..) |
ty::TyClosure(..) | ty::TyGenerator(..) |
ty::TyDynamic(..) | ty::TyStr | ty::TySlice(..) | ty::TyGenerator(..) |
ty::TyRef(_, ty::TypeAndMut { ty: _, mutbl: hir::MutMutable }) => {
Never
}
@ -2084,6 +2083,22 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
Where(ty::Binder(tys.to_vec()))
}
ty::TyClosure(def_id, substs) => {
let trait_id = obligation.predicate.def_id();
let copy_closures =
Some(trait_id) == self.tcx().lang_items().copy_trait() &&
self.tcx().has_copy_closures(def_id.krate);
let clone_closures =
Some(trait_id) == self.tcx().lang_items().clone_trait() &&
self.tcx().has_clone_closures(def_id.krate);
if copy_closures || clone_closures {
Where(ty::Binder(substs.upvar_tys(def_id, self.tcx()).collect()))
} else {
Never
}
}
ty::TyAdt(..) | ty::TyProjection(..) | ty::TyParam(..) | ty::TyAnon(..) => {
// Fallback to whatever user-defined impls exist in this case.
None
@ -2370,10 +2385,10 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
self.sized_conditions(obligation)
}
_ if Some(trait_def) == lang_items.copy_trait() => {
self.copy_conditions(obligation)
self.copy_clone_conditions(obligation)
}
_ if Some(trait_def) == lang_items.clone_trait() => {
self.copy_conditions(obligation)
self.copy_clone_conditions(obligation)
}
_ => bug!("unexpected builtin trait {:?}", trait_def)
};

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@ -2247,4 +2247,12 @@ pub fn provide(providers: &mut ty::maps::Providers) {
assert_eq!(cnum, LOCAL_CRATE);
tcx.output_filenames.clone()
};
providers.has_copy_closures = |tcx, cnum| {
assert_eq!(cnum, LOCAL_CRATE);
tcx.sess.features.borrow().copy_closures
};
providers.has_clone_closures = |tcx, cnum| {
assert_eq!(cnum, LOCAL_CRATE);
tcx.sess.features.borrow().clone_closures
};
}

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@ -38,7 +38,7 @@ pub enum InstanceDef<'tcx> {
/// drop_in_place::<T>; None for empty drop glue.
DropGlue(DefId, Option<Ty<'tcx>>),
/// Builtin method implementation, e.g. `Clone::clone`.
///`<T as Clone>::clone` shim.
CloneShim(DefId, Ty<'tcx>),
}

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@ -490,3 +490,15 @@ impl<'tcx> QueryDescription for queries::output_filenames<'tcx> {
format!("output_filenames")
}
}
impl<'tcx> QueryDescription for queries::has_clone_closures<'tcx> {
fn describe(_tcx: TyCtxt, _: CrateNum) -> String {
format!("seeing if the crate has enabled `Clone` closures")
}
}
impl<'tcx> QueryDescription for queries::has_copy_closures<'tcx> {
fn describe(_tcx: TyCtxt, _: CrateNum) -> String {
format!("seeing if the crate has enabled `Copy` closures")
}
}

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@ -326,6 +326,9 @@ define_maps! { <'tcx>
[] fn compile_codegen_unit: CompileCodegenUnit(InternedString) -> Stats,
[] fn output_filenames: output_filenames_node(CrateNum)
-> Arc<OutputFilenames>,
[] fn has_copy_closures: HasCopyClosures(CrateNum) -> bool,
[] fn has_clone_closures: HasCloneClosures(CrateNum) -> bool,
}
//////////////////////////////////////////////////////////////////////

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@ -218,6 +218,16 @@ impl CrateMetadata {
attr::contains_name(&attrs, "no_builtins")
}
pub fn has_copy_closures(&self) -> bool {
let attrs = self.get_item_attrs(CRATE_DEF_INDEX);
attr::contains_feature_attr(&attrs, "copy_closures")
}
pub fn has_clone_closures(&self) -> bool {
let attrs = self.get_item_attrs(CRATE_DEF_INDEX);
attr::contains_feature_attr(&attrs, "clone_closures")
}
pub fn panic_strategy(&self) -> PanicStrategy {
self.root.panic_strategy.clone()
}

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@ -231,6 +231,9 @@ provide! { <'tcx> tcx, def_id, other, cdata,
}
used_crate_source => { Rc::new(cdata.source.clone()) }
has_copy_closures => { cdata.has_copy_closures() }
has_clone_closures => { cdata.has_clone_closures() }
}
pub fn provide_local<'tcx>(providers: &mut Providers<'tcx>) {

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@ -296,9 +296,15 @@ fn build_clone_shim<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
let len = len.val.to_const_int().unwrap().to_u64().unwrap();
builder.array_shim(ty, len)
}
ty::TyTuple(tys, _) => builder.tuple_shim(tys),
ty::TyClosure(def_id, substs) => {
builder.tuple_like_shim(
&substs.upvar_tys(def_id, tcx).collect::<Vec<_>>(),
AggregateKind::Closure(def_id, substs)
)
}
ty::TyTuple(tys, _) => builder.tuple_like_shim(&**tys, AggregateKind::Tuple),
_ => {
bug!("clone shim for `{:?}` which is not `Copy` and is not an aggregate", self_ty);
bug!("clone shim for `{:?}` which is not `Copy` and is not an aggregate", self_ty)
}
};
@ -613,7 +619,12 @@ impl<'a, 'tcx> CloneShimBuilder<'a, 'tcx> {
self.block(vec![], TerminatorKind::Resume, true);
}
fn tuple_shim(&mut self, tys: &ty::Slice<Ty<'tcx>>) {
fn tuple_like_shim(&mut self, tys: &[ty::Ty<'tcx>], kind: AggregateKind<'tcx>) {
match kind {
AggregateKind::Tuple | AggregateKind::Closure(..) => (),
_ => bug!("only tuples and closures are accepted"),
};
let rcvr = Lvalue::Local(Local::new(1+0)).deref();
let mut returns = Vec::new();
@ -646,17 +657,17 @@ impl<'a, 'tcx> CloneShimBuilder<'a, 'tcx> {
}
}
// `return (returns[0], returns[1], ..., returns[tys.len() - 1]);`
// `return kind(returns[0], returns[1], ..., returns[tys.len() - 1]);`
let ret_statement = self.make_statement(
StatementKind::Assign(
Lvalue::Local(RETURN_POINTER),
Rvalue::Aggregate(
box AggregateKind::Tuple,
box kind,
returns.into_iter().map(Operand::Consume).collect()
)
)
);
self.block(vec![ret_statement], TerminatorKind::Return, false);
self.block(vec![ret_statement], TerminatorKind::Return, false);
}
}

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@ -500,6 +500,20 @@ pub fn first_attr_value_str_by_name(attrs: &[Attribute], name: &str) -> Option<S
.and_then(|at| at.value_str())
}
/// Check if `attrs` contains an attribute like `#![feature(feature_name)]`.
/// This will not perform any "sanity checks" on the form of the attributes.
pub fn contains_feature_attr(attrs: &[Attribute], feature_name: &str) -> bool {
attrs.iter().any(|item| {
item.check_name("feature") &&
item.meta_item_list().map(|list| {
list.iter().any(|mi| {
mi.word().map(|w| w.name() == feature_name)
.unwrap_or(false)
})
}).unwrap_or(false)
})
}
/* Higher-level applications */
pub fn find_crate_name(attrs: &[Attribute]) -> Option<Symbol> {

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@ -385,6 +385,10 @@ declare_features! (
// allow '|' at beginning of match arms (RFC 1925)
(active, match_beginning_vert, "1.21.0", Some(44101)),
// Copy/Clone closures (RFC 2132)
(active, clone_closures, "1.22.0", Some(44490)),
(active, copy_closures, "1.22.0", Some(44490)),
);
declare_features! (
@ -1573,7 +1577,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
pub fn get_features(span_handler: &Handler, krate_attrs: &[ast::Attribute]) -> Features {
let mut features = Features::new();
let mut feature_checker = MutexFeatureChecker::default();
let mut feature_checker = FeatureChecker::default();
for attr in krate_attrs {
if !attr.check_name("feature") {
@ -1622,14 +1626,16 @@ pub fn get_features(span_handler: &Handler, krate_attrs: &[ast::Attribute]) -> F
features
}
// A collector for mutually-exclusive features and their flag spans
/// A collector for mutually exclusive and interdependent features and their flag spans.
#[derive(Default)]
struct MutexFeatureChecker {
struct FeatureChecker {
proc_macro: Option<Span>,
custom_attribute: Option<Span>,
copy_closures: Option<Span>,
clone_closures: Option<Span>,
}
impl MutexFeatureChecker {
impl FeatureChecker {
// If this method turns out to be a hotspot due to branching,
// the branching can be eliminated by modifying `set!()` to set these spans
// only for the features that need to be checked for mutual exclusion.
@ -1642,6 +1648,14 @@ impl MutexFeatureChecker {
if features.custom_attribute {
self.custom_attribute = self.custom_attribute.or(Some(span));
}
if features.copy_closures {
self.copy_closures = self.copy_closures.or(Some(span));
}
if features.clone_closures {
self.clone_closures = self.clone_closures.or(Some(span));
}
}
fn check(self, handler: &Handler) {
@ -1653,6 +1667,15 @@ impl MutexFeatureChecker {
panic!(FatalError);
}
if let (Some(span), None) = (self.copy_closures, self.clone_closures) {
handler.struct_span_err(span, "`#![feature(copy_closures)]` can only be used with \
`#![feature(clone_closures)]`")
.span_note(span, "`#![feature(copy_closures)]` declared here")
.emit();
panic!(FatalError);
}
}
}

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@ -0,0 +1,21 @@
// 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.
#[derive(Clone)]
struct S(i32);
fn main() {
let a = S(5);
let hello = move || {
println!("Hello {}", a.0);
};
let hello = hello.clone(); //~ ERROR no method named `clone` found for type
}

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@ -0,0 +1,19 @@
// 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.
fn main() {
let a = 5;
let hello = || {
println!("Hello {}", a);
};
let b = hello;
let c = hello; //~ ERROR use of moved value: `hello` [E0382]
}

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@ -0,0 +1,24 @@
// 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.
// Check that closures do not implement `Clone` if their environment is not `Clone`.
#![feature(clone_closures)]
struct S(i32);
fn main() {
let a = S(5);
let hello = move || {
println!("Hello {}", a.0);
};
let hello = hello.clone(); //~ ERROR the trait bound `S: std::clone::Clone` is not satisfied
}

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@ -0,0 +1,24 @@
// 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.
// Check that closures do not implement `Copy` if their environment is not `Copy`.
#![feature(copy_closures)]
#![feature(clone_closures)]
fn main() {
let mut a = 5;
let hello = || {
a += 1;
};
let b = hello;
let c = hello; //~ ERROR use of moved value: `hello` [E0382]
}

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@ -0,0 +1,29 @@
// 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.
// Check that closures implement `Clone`.
#![feature(clone_closures)]
#[derive(Clone)]
struct S(i32);
fn main() {
let mut a = S(5);
let mut hello = move || {
a.0 += 1;
println!("Hello {}", a.0);
a.0
};
let mut hello2 = hello.clone();
assert_eq!(6, hello2());
assert_eq!(6, hello());
}

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@ -0,0 +1,28 @@
// 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.
// Check that closures implement `Copy`.
#![feature(copy_closures)]
#![feature(clone_closures)]
fn call<T, F: FnOnce() -> T>(f: F) -> T { f() }
fn main() {
let a = 5;
let hello = || {
println!("Hello {}", a);
a
};
assert_eq!(5, call(hello.clone()));
assert_eq!(5, call(hello));
assert_eq!(5, call(hello));
}