Skip to content

Commit eec30ea

Browse files
borsbors
authored
Auto merge of #35453 - jseyfried:hygienize_metavariables, r=nrc
macros: Make metavariables hygienic This PR makes metavariables hygienic. For example, consider: ```rust macro_rules! foo { ($x:tt) => { // Suppose that this token tree argument is always a metavariable. macro_rules! bar { ($x:expr, $y:expr) => { ($x, $y) } } } } fn main() { foo!($z); // This currently compiles. foo!($y); // This is an error today but compiles after this PR. } ``` Today, the `macro_rules! bar { ... }` definition is only valid when the metavariable passed to `foo` is not `$y` (since it unhygienically conflicts with the `$y` in the definition of `bar`) or `$x` (c.f. #35450). After this PR, the definition of `bar` is always valid (and `bar!(a, b)` always expands to `(a, b)` as expected). This can break code that was allowed in #34925 (landed two weeks ago). For example, ```rust macro_rules! outer { ($t:tt) => { macro_rules! inner { ($i:item) => { $t } } } } outer!($i); // This `$i` should not interact with the `$i` in the definition of `inner!`. inner!(fn main() {}); // After this PR, this is an error ("unknown macro variable `i`"). ``` Due to the severe limitations on nested `macro_rules!` before #34925, this is not a breaking change for stable/beta. Fixes #35450. r? @nrc
2 parents 2b7ea14 + 95b68aa commit eec30ea

File tree

6 files changed

+41
-14
lines changed

6 files changed

+41
-14
lines changed

‎src/libsyntax/ext/tt/macro_parser.rs

+5-5
Original file line numberDiff line numberDiff line change
@@ -79,7 +79,7 @@ pub use self::ParseResult::*;
7979
use self::TokenTreeOrTokenTreeVec::*;
8080

8181
use ast;
82-
use ast::{Name, Ident};
82+
use ast::Ident;
8383
use syntax_pos::{self, BytePos, mk_sp, Span};
8484
use codemap::Spanned;
8585
use errors::FatalError;
@@ -202,9 +202,9 @@ pub enum NamedMatch {
202202
}
203203

204204
pub fn nameize(p_s: &ParseSess, ms: &[TokenTree], res: &[Rc<NamedMatch>])
205-
-> ParseResult<HashMap<Name, Rc<NamedMatch>>> {
205+
-> ParseResult<HashMap<Ident, Rc<NamedMatch>>> {
206206
fn n_rec(p_s: &ParseSess, m: &TokenTree, res: &[Rc<NamedMatch>],
207-
ret_val: &mut HashMap<Name, Rc<NamedMatch>>, idx: &mut usize)
207+
ret_val: &mut HashMap<Ident, Rc<NamedMatch>>, idx: &mut usize)
208208
-> Result<(), (syntax_pos::Span, String)> {
209209
match *m {
210210
TokenTree::Sequence(_, ref seq) => {
@@ -218,7 +218,7 @@ pub fn nameize(p_s: &ParseSess, ms: &[TokenTree], res: &[Rc<NamedMatch>])
218218
}
219219
}
220220
TokenTree::Token(sp, MatchNt(bind_name, _)) => {
221-
match ret_val.entry(bind_name.name) {
221+
match ret_val.entry(bind_name) {
222222
Vacant(spot) => {
223223
spot.insert(res[*idx].clone());
224224
*idx += 1;
@@ -257,7 +257,7 @@ pub enum ParseResult<T> {
257257
Error(syntax_pos::Span, String)
258258
}
259259

260-
pub type NamedParseResult = ParseResult<HashMap<Name, Rc<NamedMatch>>>;
260+
pub type NamedParseResult = ParseResult<HashMap<Ident, Rc<NamedMatch>>>;
261261
pub type PositionalParseResult = ParseResult<Vec<Rc<NamedMatch>>>;
262262

263263
/// Perform a token equality check, ignoring syntax context (that is, an

‎src/libsyntax/ext/tt/macro_rules.rs

+2-2
Original file line numberDiff line numberDiff line change
@@ -302,7 +302,7 @@ pub fn compile<'cx>(cx: &'cx mut ExtCtxt,
302302
let mut valid = true;
303303

304304
// Extract the arguments:
305-
let lhses = match **argument_map.get(&lhs_nm.name).unwrap() {
305+
let lhses = match **argument_map.get(&lhs_nm).unwrap() {
306306
MatchedSeq(ref s, _) => {
307307
s.iter().map(|m| match **m {
308308
MatchedNonterminal(NtTT(ref tt)) => {
@@ -315,7 +315,7 @@ pub fn compile<'cx>(cx: &'cx mut ExtCtxt,
315315
_ => cx.span_bug(def.span, "wrong-structured lhs")
316316
};
317317

318-
let rhses = match **argument_map.get(&rhs_nm.name).unwrap() {
318+
let rhses = match **argument_map.get(&rhs_nm).unwrap() {
319319
MatchedSeq(ref s, _) => {
320320
s.iter().map(|m| match **m {
321321
MatchedNonterminal(NtTT(ref tt)) => (**tt).clone(),

‎src/libsyntax/ext/tt/transcribe.rs

+5-5
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@
99
// except according to those terms.
1010
use self::LockstepIterSize::*;
1111

12-
use ast::{Ident, Name};
12+
use ast::Ident;
1313
use syntax_pos::{Span, DUMMY_SP};
1414
use errors::{Handler, DiagnosticBuilder};
1515
use ext::tt::macro_parser::{NamedMatch, MatchedSeq, MatchedNonterminal};
@@ -38,7 +38,7 @@ pub struct TtReader<'a> {
3838
/// the unzipped tree:
3939
stack: Vec<TtFrame>,
4040
/* for MBE-style macro transcription */
41-
interpolations: HashMap<Name, Rc<NamedMatch>>,
41+
interpolations: HashMap<Ident, Rc<NamedMatch>>,
4242
imported_from: Option<Ident>,
4343

4444
// Some => return imported_from as the next token
@@ -57,7 +57,7 @@ pub struct TtReader<'a> {
5757
/// `src` contains no `TokenTree::Sequence`s, `MatchNt`s or `SubstNt`s, `interp` can
5858
/// (and should) be None.
5959
pub fn new_tt_reader(sp_diag: &Handler,
60-
interp: Option<HashMap<Name, Rc<NamedMatch>>>,
60+
interp: Option<HashMap<Ident, Rc<NamedMatch>>>,
6161
imported_from: Option<Ident>,
6262
src: Vec<tokenstream::TokenTree>)
6363
-> TtReader {
@@ -71,7 +71,7 @@ pub fn new_tt_reader(sp_diag: &Handler,
7171
/// `src` contains no `TokenTree::Sequence`s, `MatchNt`s or `SubstNt`s, `interp` can
7272
/// (and should) be None.
7373
pub fn new_tt_reader_with_doc_flag(sp_diag: &Handler,
74-
interp: Option<HashMap<Name, Rc<NamedMatch>>>,
74+
interp: Option<HashMap<Ident, Rc<NamedMatch>>>,
7575
imported_from: Option<Ident>,
7676
src: Vec<tokenstream::TokenTree>,
7777
desugar_doc_comments: bool)
@@ -119,7 +119,7 @@ fn lookup_cur_matched_by_matched(r: &TtReader, start: Rc<NamedMatch>) -> Rc<Name
119119
}
120120

121121
fn lookup_cur_matched(r: &TtReader, name: Ident) -> Option<Rc<NamedMatch>> {
122-
let matched_opt = r.interpolations.get(&name.name).cloned();
122+
let matched_opt = r.interpolations.get(&name).cloned();
123123
matched_opt.map(|s| lookup_cur_matched_by_matched(r, s))
124124
}
125125

‎src/test/compile-fail/issue-35450.rs

+16
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,16 @@
1+
// Copyright 2016 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+
macro_rules! m { ($t:tt) => { $t } }
12+
13+
fn main() {
14+
m!($t); //~ ERROR unknown macro variable
15+
//~| ERROR expected expression
16+
}

‎src/test/compile-fail/macro-tt-matchers.rs

+12-1
Original file line numberDiff line numberDiff line change
@@ -16,5 +16,16 @@ macro_rules! foo {
1616

1717
foo!(Box);
1818

19+
macro_rules! bar {
20+
($x:tt) => {
21+
macro_rules! baz {
22+
($x:tt, $y:tt) => { ($x, $y) }
23+
}
24+
}
25+
}
26+
1927
#[rustc_error]
20-
fn main() {} //~ ERROR compilation successful
28+
fn main() { //~ ERROR compilation successful
29+
bar!($y);
30+
let _: (i8, i16) = baz!(0i8, 0i16);
31+
}

‎src/test/run-pass-fulldeps/auxiliary/procedural_mbe_matching.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -36,7 +36,7 @@ fn expand_mbe_matches(cx: &mut ExtCtxt, sp: Span, args: &[TokenTree])
3636

3737
let mac_expr = match TokenTree::parse(cx, &mbe_matcher[..], args) {
3838
Success(map) => {
39-
match (&*map[&str_to_ident("matched").name], &*map[&str_to_ident("pat").name]) {
39+
match (&*map[&str_to_ident("matched")], &*map[&str_to_ident("pat")]) {
4040
(&MatchedNonterminal(NtExpr(ref matched_expr)),
4141
&MatchedSeq(ref pats, seq_sp)) => {
4242
let pats: Vec<P<Pat>> = pats.iter().map(|pat_nt|

0 commit comments

Comments
 (0)