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Auto merge of #26699 - eddyb:unstable-prelude_import, r=huonw
Closes #26690.
2 parents 26f0cd5 + 6a3b385 commit ed14593

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6 files changed

+57
-19
lines changed

6 files changed

+57
-19
lines changed

‎src/librustc_driver/driver.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -547,7 +547,7 @@ pub fn phase_2_configure_and_expand(sess: &Session,
547547
sess.diagnostic()));
548548

549549
krate = time(time_passes, "prelude injection", krate, |krate|
550-
syntax::std_inject::maybe_inject_prelude(krate));
550+
syntax::std_inject::maybe_inject_prelude(&sess.parse_sess, krate));
551551

552552
time(time_passes, "checking that all macro invocations are gone", &krate, |krate|
553553
syntax::ext::expand::check_for_macros(&sess.parse_sess, krate));

‎src/libsyntax/feature_gate.rs

+5-1
Original file line numberDiff line numberDiff line change
@@ -155,6 +155,9 @@ const KNOWN_FEATURES: &'static [(&'static str, &'static str, Status)] = &[
155155

156156
// Allows the definition of `const fn` functions.
157157
("const_fn", "1.2.0", Active),
158+
159+
// Allows using #[prelude_import] on glob `use` items.
160+
("prelude_import", "1.2.0", Active),
158161
];
159162
// (changing above list without updating src/doc/reference.md makes @cmr sad)
160163

@@ -265,7 +268,8 @@ pub const KNOWN_ATTRIBUTES: &'static [(&'static str, AttributeType)] = &[
265268
and may be removed in the future")),
266269

267270
// used in resolve
268-
("prelude_import", Whitelisted),
271+
("prelude_import", Gated("prelude_import",
272+
"`#[prelude_import]` is for use by rustc only")),
269273

270274
// FIXME: #14407 these are only looked at on-demand so we can't
271275
// guarantee they'll have already been checked

‎src/libsyntax/print/pprust.rs

+3-1
Original file line numberDiff line numberDiff line change
@@ -120,11 +120,13 @@ pub fn print_crate<'a>(cm: &'a CodeMap,
120120
// of the feature gate, so we fake them up here.
121121

122122
let no_std_meta = attr::mk_word_item(InternedString::new("no_std"));
123+
let prelude_import_meta = attr::mk_word_item(InternedString::new("prelude_import"));
123124

124125
// #![feature(no_std)]
125126
let fake_attr = attr::mk_attr_inner(attr::mk_attr_id(),
126127
attr::mk_list_item(InternedString::new("feature"),
127-
vec![no_std_meta.clone()]));
128+
vec![no_std_meta.clone(),
129+
prelude_import_meta]));
128130
try!(s.print_attribute(&fake_attr));
129131

130132
// #![no_std]

‎src/libsyntax/std_inject.rs

+33-15
Original file line numberDiff line numberDiff line change
@@ -10,16 +10,35 @@
1010

1111
use ast;
1212
use attr;
13-
use codemap::DUMMY_SP;
13+
use codemap::{DUMMY_SP, Span, ExpnInfo, NameAndSpan, MacroAttribute};
1414
use codemap;
1515
use fold::Folder;
1616
use fold;
1717
use parse::token::InternedString;
1818
use parse::token::special_idents;
19-
use parse::token;
19+
use parse::{token, ParseSess};
2020
use ptr::P;
2121
use util::small_vector::SmallVector;
2222

23+
/// Craft a span that will be ignored by the stability lint's
24+
/// call to codemap's is_internal check.
25+
/// The expanded code uses the unstable `#[prelude_import]` attribute.
26+
fn ignored_span(sess: &ParseSess, sp: Span) -> Span {
27+
let info = ExpnInfo {
28+
call_site: DUMMY_SP,
29+
callee: NameAndSpan {
30+
name: "std_inject".to_string(),
31+
format: MacroAttribute,
32+
span: None,
33+
allow_internal_unstable: true,
34+
}
35+
};
36+
let expn_id = sess.codemap().record_expansion(info);
37+
let mut sp = sp;
38+
sp.expn_id = expn_id;
39+
return sp;
40+
}
41+
2342
pub fn maybe_inject_crates_ref(krate: ast::Crate, alt_std_name: Option<String>)
2443
-> ast::Crate {
2544
if use_std(&krate) {
@@ -29,9 +48,12 @@ pub fn maybe_inject_crates_ref(krate: ast::Crate, alt_std_name: Option<String>)
2948
}
3049
}
3150

32-
pub fn maybe_inject_prelude(krate: ast::Crate) -> ast::Crate {
51+
pub fn maybe_inject_prelude(sess: &ParseSess, krate: ast::Crate) -> ast::Crate {
3352
if use_std(&krate) {
34-
inject_prelude(krate)
53+
let mut fold = PreludeInjector {
54+
span: ignored_span(sess, DUMMY_SP)
55+
};
56+
fold.fold_crate(krate)
3557
} else {
3658
krate
3759
}
@@ -80,8 +102,9 @@ fn inject_crates_ref(krate: ast::Crate, alt_std_name: Option<String>) -> ast::Cr
80102
fold.fold_crate(krate)
81103
}
82104

83-
struct PreludeInjector;
84-
105+
struct PreludeInjector {
106+
span: Span
107+
}
85108

86109
impl fold::Folder for PreludeInjector {
87110
fn fold_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
@@ -107,7 +130,7 @@ impl fold::Folder for PreludeInjector {
107130

108131
fn fold_mod(&mut self, mut mod_: ast::Mod) -> ast::Mod {
109132
let prelude_path = ast::Path {
110-
span: DUMMY_SP,
133+
span: self.span,
111134
global: false,
112135
segments: vec![
113136
ast::PathSegment {
@@ -131,27 +154,22 @@ impl fold::Folder for PreludeInjector {
131154
ident: special_idents::invalid,
132155
node: ast::ItemUse(vp),
133156
attrs: vec![ast::Attribute {
134-
span: DUMMY_SP,
157+
span: self.span,
135158
node: ast::Attribute_ {
136159
id: attr::mk_attr_id(),
137160
style: ast::AttrOuter,
138161
value: P(ast::MetaItem {
139-
span: DUMMY_SP,
162+
span: self.span,
140163
node: ast::MetaWord(token::get_name(
141164
special_idents::prelude_import.name)),
142165
}),
143166
is_sugared_doc: false,
144167
},
145168
}],
146169
vis: ast::Inherited,
147-
span: DUMMY_SP,
170+
span: self.span,
148171
}));
149172

150173
fold::noop_fold_mod(mod_, self)
151174
}
152175
}
153-
154-
fn inject_prelude(krate: ast::Crate) -> ast::Crate {
155-
let mut fold = PreludeInjector;
156-
fold.fold_crate(krate)
157-
}

‎src/test/compile-fail/feature-gate-prelude_import.rs

+14
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,14 @@
1+
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2+
// file at the top-level directory of this distribution and at
3+
// http://rust-lang.org/COPYRIGHT.
4+
//
5+
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6+
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7+
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8+
// option. This file may not be copied, modified, or distributed
9+
// except according to those terms.
10+
11+
#[prelude_import] //~ ERROR `#[prelude_import]` is for use by rustc only
12+
use std::prelude::v1::*;
13+
14+
fn main() {}

‎src/test/pretty/issue-4264.pp

+1-1
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
#![feature(no_std)]
1+
#![feature(no_std, prelude_import)]
22
#![no_std]
33
#[prelude_import]
44
use std::prelude::v1::*;

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