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Support extern in paths

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This commit is contained in:
Vadim Petrochenkov 2018-01-01 17:42:32 +03:00
parent b107f720e5
commit 32db83b16e
14 changed files with 185 additions and 26 deletions
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26
src/librustc_resolve/lib.rs
View file

@ -2982,6 +2982,8 @@ impl<'a> Resolver<'a> {
let msg = "There are too many initial `super`s.".to_string();
return PathResult::Failed(ident.span, msg, false);
}
} else if i == 0 && ns == TypeNS && name == keywords::Extern.name() {
continue;
}
allow_super = false;
@ -2996,16 +2998,19 @@ impl<'a> Resolver<'a> {
// `$crate::a::b`
module = Some(self.resolve_crate_root(ident.node.ctxt));
continue
} else if i == 1 && self.session.features.borrow().extern_absolute_paths &&
path[0].node.name == keywords::CrateRoot.name() &&
!token::Ident(ident.node).is_path_segment_keyword() {
// `::extern_crate::a::b`
let crate_id = self.crate_loader.resolve_crate_from_path(name, ident.span);
let crate_root =
self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
self.populate_module_if_necessary(crate_root);
module = Some(crate_root);
continue
} else if i == 1 && !token::Ident(ident.node).is_path_segment_keyword() {
let prev_name = path[0].node.name;
if prev_name == keywords::Extern.name() ||
prev_name == keywords::CrateRoot.name() &&
self.session.features.borrow().extern_absolute_paths {
// `::extern_crate::a::b`
let crate_id = self.crate_loader.resolve_crate_from_path(name, ident.span);
let crate_root =
self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
self.populate_module_if_necessary(crate_root);
module = Some(crate_root);
continue
}
}
}
@ -3015,6 +3020,7 @@ impl<'a> Resolver<'a> {
name == keywords::SelfValue.name() && i != 0 ||
name == keywords::SelfType.name() && i != 0 ||
name == keywords::Super.name() && i != 0 ||
name == keywords::Extern.name() && i != 0 ||
name == keywords::Crate.name() && i != 1 &&
path[0].node.name != keywords::CrateRoot.name() {
let name_str = if name == keywords::CrateRoot.name() {

18
src/librustc_resolve/resolve_imports.rs
View file

@ -604,17 +604,20 @@ impl<'a, 'b:'a> ImportResolver<'a, 'b> {
self.current_module = directive.parent;
let ImportDirective { ref module_path, span, .. } = *directive;
// Extern crate mode for absolute paths needs some
// special support for single-segment imports.
let extern_absolute_paths = self.session.features.borrow().extern_absolute_paths;
if module_path.len() == 1 && module_path[0].node.name == keywords::CrateRoot.name() {
// FIXME: Last path segment is treated specially in import resolution, so extern crate
// mode for absolute paths needs some special support for single-segment imports.
if module_path.len() == 1 && (module_path[0].node.name == keywords::CrateRoot.name() ||
module_path[0].node.name == keywords::Extern.name()) {
let is_extern = module_path[0].node.name == keywords::Extern.name() ||
self.session.features.borrow().extern_absolute_paths;
match directive.subclass {
GlobImport { .. } if extern_absolute_paths => {
GlobImport { .. } if is_extern => {
return Some((directive.span,
"cannot glob-import all possible crates".to_string()));
}
SingleImport { source, target, .. } => {
let crate_root = if source.name == keywords::Crate.name() {
let crate_root = if source.name == keywords::Crate.name() &&
module_path[0].node.name != keywords::Extern.name() {
if target.name == keywords::Crate.name() {
return Some((directive.span,
"crate root imports need to be explicitly named: \
@ -622,8 +625,7 @@ impl<'a, 'b:'a> ImportResolver<'a, 'b> {
} else {
Some(self.resolve_crate_root(source.ctxt.modern()))
}
} else if extern_absolute_paths &&
!token::Ident(source).is_path_segment_keyword() {
} else if is_extern && !token::Ident(source).is_path_segment_keyword() {
let crate_id =
self.crate_loader.resolve_crate_from_path(source.name, directive.span);
let crate_root =

6
src/libsyntax/feature_gate.rs
View file

@ -450,6 +450,9 @@ declare_features! (
// Allows use of the :lifetime macro fragment specifier
(active, macro_lifetime_matcher, "1.24.0", Some(46895)),
// `extern` in paths
(active, extern_in_paths, "1.23.0", Some(44660)),
);
declare_features! (
@ -1790,6 +1793,9 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
if segment.identifier.name == keywords::Crate.name() {
gate_feature_post!(&self, crate_in_paths, segment.span,
"`crate` in paths is experimental");
} else if segment.identifier.name == keywords::Extern.name() {
gate_feature_post!(&self, extern_in_paths, segment.span,
"`extern` in paths is experimental");
}
}

15
src/libsyntax/parse/parser.rs
View file

@ -1387,7 +1387,7 @@ impl<'a> Parser<'a> {
None
};
(ident, TraitItemKind::Const(ty, default), ast::Generics::default())
} else if self.token.is_path_start() {
} else if self.token.is_path_start() && !self.is_extern_non_path() {
// trait item macro.
// code copied from parse_macro_use_or_failure... abstraction!
let prev_span = self.prev_span;
@ -4037,6 +4037,10 @@ impl<'a> Parser<'a> {
self.token.is_keyword(keywords::Crate) && self.look_ahead(1, |t| t != &token::ModSep)
}
fn is_extern_non_path(&self) -> bool {
self.token.is_keyword(keywords::Extern) && self.look_ahead(1, |t| t != &token::ModSep)
}
fn eat_auto_trait(&mut self) -> bool {
if self.token.is_keyword(keywords::Auto)
&& self.look_ahead(1, |t| t.is_keyword(keywords::Trait))
@ -4152,10 +4156,12 @@ impl<'a> Parser<'a> {
// like a path (1 token), but it fact not a path.
// `union::b::c` - path, `union U { ... }` - not a path.
// `crate::b::c` - path, `crate struct S;` - not a path.
// `extern::b::c` - path, `extern crate c;` - not a path.
} else if self.token.is_path_start() &&
!self.token.is_qpath_start() &&
!self.is_union_item() &&
!self.is_crate_vis() {
!self.is_crate_vis() &&
!self.is_extern_non_path() {
let pth = self.parse_path(PathStyle::Expr)?;
if !self.eat(&token::Not) {
@ -5236,7 +5242,7 @@ impl<'a> Parser<'a> {
-> PResult<'a, (Ident, Vec<ast::Attribute>, ast::Generics,
ast::ImplItemKind)> {
// code copied from parse_macro_use_or_failure... abstraction!
if self.token.is_path_start() {
if self.token.is_path_start() && !self.is_extern_non_path() {
// Method macro.
let prev_span = self.prev_span;
@ -6238,7 +6244,8 @@ impl<'a> Parser<'a> {
return Ok(Some(item));
}
if self.eat_keyword(keywords::Extern) {
if self.check_keyword(keywords::Extern) && self.is_extern_non_path() {
self.bump(); // `extern`
if self.eat_keyword(keywords::Crate) {
return Ok(Some(self.parse_item_extern_crate(lo, visibility, attrs)?));
}

1
src/libsyntax/parse/token.rs
View file

@ -359,6 +359,7 @@ impl Token {
Some(id) => id.name == keywords::Super.name() ||
id.name == keywords::SelfValue.name() ||
id.name == keywords::SelfType.name() ||
id.name == keywords::Extern.name() ||
id.name == keywords::Crate.name() ||
id.name == keywords::DollarCrate.name(),
None => false,

6
src/test/parse-fail/keyword-extern-as-identifier.rs → src/test/compile-fail/keyword-extern-as-identifier.rs
View file

@ -8,10 +8,8 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// compile-flags: -Z parse-only
// This file was auto-generated using 'src/etc/generate-keyword-tests.py extern'
#![feature(extern_in_paths)]
fn main() {
let extern = "foo"; //~ error: expected pattern, found keyword `extern`
let extern = 0; //~ ERROR expected unit struct/variant or constant, found module `extern`
}

15
src/test/compile-fail/rfc-2126-extern-in-paths/auxiliary/xcrate.rs Normal file
View file

@ -0,0 +1,15 @@
// 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(Debug)]
pub struct S;
#[derive(Debug)]
pub struct Z;

15
src/test/compile-fail/rfc-2126-extern-in-paths/non-existent-1.rs Normal file
View file

@ -0,0 +1,15 @@
// 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(extern_in_paths)]
use extern::xcrate::S; //~ ERROR can't find crate for `xcrate`
fn main() {}

15
src/test/compile-fail/rfc-2126-extern-in-paths/non-existent-2.rs Normal file
View file

@ -0,0 +1,15 @@
// 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(extern_in_paths)]
fn main() {
let s = extern::xcrate::S; //~ ERROR can't find crate for `xcrate`
}

15
src/test/compile-fail/rfc-2126-extern-in-paths/non-existent-3.rs Normal file
View file

@ -0,0 +1,15 @@
// 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(extern_in_paths)]
use extern::ycrate; //~ ERROR can't find crate for `ycrate`
fn main() {}

23
src/test/compile-fail/rfc-2126-extern-in-paths/single-segment.rs Normal file
View file

@ -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.
// aux-build:xcrate.rs
#![feature(extern_in_paths)]
use extern; //~ ERROR unresolved import `extern`
//~^ NOTE no `extern` in the root
use extern::*; //~ ERROR unresolved import `extern::*`
//~^ NOTE cannot glob-import all possible crates
fn main() {
let s = extern::xcrate; //~ ERROR expected value, found module `extern::xcrate`
//~^ NOTE not a value
}

31
src/test/run-pass/rfc-2126-extern-absolute-paths/extern.rs Normal file
View file

@ -0,0 +1,31 @@
// 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.
// aux-build:xcrate.rs
#![feature(extern_in_paths)]
use extern::xcrate::Z;
fn f() {
use extern::xcrate;
use extern::xcrate as ycrate;
let s = xcrate::S;
assert_eq!(format!("{:?}", s), "S");
let z = ycrate::Z;
assert_eq!(format!("{:?}", z), "Z");
}
fn main() {
let s = extern::xcrate::S;
assert_eq!(format!("{:?}", s), "S");
let z = Z;
assert_eq!(format!("{:?}", z), "Z");
}

15
src/test/ui/feature-gate-extern_in_paths.rs Normal file
View file

@ -0,0 +1,15 @@
// 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.
struct S;
fn main() {
let _ = extern::std::vec::Vec::new(); //~ ERROR `extern` in paths is experimental
}

10
src/test/ui/feature-gate-extern_in_paths.stderr Normal file
View file

@ -0,0 +1,10 @@
error: `extern` in paths is experimental (see issue #44660)
--> $DIR/feature-gate-extern_in_paths.rs:14:13
|
14 | let _ = extern::std::vec::Vec::new(); //~ ERROR `extern` in paths is experimental
| ^^^^^^
|
= help: add #![feature(extern_in_paths)] to the crate attributes to enable
error: aborting due to previous error