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implement edition-specific :pat behavior for 2015/18

This commit is contained in:
mark 2020-11-10 18:00:53 -06:00
parent e461b8137f
commit 1a7d00a529
14 changed files with 193 additions and 75 deletions
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33
compiler/rustc_expand/src/mbe/macro_parser.rs
View File

@ -77,9 +77,9 @@ use TokenTreeOrTokenTreeSlice::*;
use crate::mbe::{self, TokenTree};
use rustc_ast::token::{self, DocComment, Nonterminal, Token};
use rustc_parse::parser::Parser;
use rustc_parse::parser::{OrPatNonterminalMode, Parser};
use rustc_session::parse::ParseSess;
use rustc_span::symbol::MacroRulesNormalizedIdent;
use rustc_span::{edition::Edition, symbol::MacroRulesNormalizedIdent};
use smallvec::{smallvec, SmallVec};
@ -414,6 +414,18 @@ fn token_name_eq(t1: &Token, t2: &Token) -> bool {
}
}
/// In edition 2015/18, `:pat` can only match `pat<no_top_alt>` because otherwise, we have
/// breakage. As of edition 2021, `:pat` matches `top_pat`.
///
/// See <https://github.com/rust-lang/rust/issues/54883> for more info.
fn or_pat_mode(edition: Edition) -> OrPatNonterminalMode {
match edition {
Edition::Edition2015 | Edition::Edition2018 => OrPatNonterminalMode::NoTopAlt,
// FIXME(mark-i-m): uncomment this when edition 2021 machinery is added.
// Edition::Edition2021 => OrPatNonterminalMode::TopPat,
}
}
/// Process the matcher positions of `cur_items` until it is empty. In the process, this will
/// produce more items in `next_items`, `eof_items`, and `bb_items`.
///
@ -553,10 +565,14 @@ fn inner_parse_loop<'root, 'tt>(
// We need to match a metavar with a valid ident... call out to the black-box
// parser by adding an item to `bb_items`.
TokenTree::MetaVarDecl(_, _, kind) => {
// Built-in nonterminals never start with these tokens,
// so we can eliminate them from consideration.
if Parser::nonterminal_may_begin_with(kind, token) {
TokenTree::MetaVarDecl(span, _, kind) => {
// Built-in nonterminals never start with these tokens, so we can eliminate
// them from consideration.
//
// We use the span of the metavariable declaration to determine any
// edition-specific matching behavior for non-terminals.
if Parser::nonterminal_may_begin_with(kind, token, or_pat_mode(span.edition()))
{
bb_items.push(item);
}
}
@ -717,7 +733,10 @@ pub(super) fn parse_tt(parser: &mut Cow<'_, Parser<'_>>, ms: &[TokenTree]) -> Na
let mut item = bb_items.pop().unwrap();
if let TokenTree::MetaVarDecl(span, _, kind) = item.top_elts.get_tt(item.idx) {
let match_cur = item.match_cur;
let nt = match parser.to_mut().parse_nonterminal(kind) {
// We use the span of the metavariable declaration to determine any
// edition-specific matching behavior for non-terminals.
let nt = match parser.to_mut().parse_nonterminal(kind, or_pat_mode(span.edition()))
{
Err(mut err) => {
err.span_label(
span,

8
compiler/rustc_parse/src/parser/expr.rs
View File

@ -1,4 +1,4 @@
use super::pat::{GateOr, PARAM_EXPECTED};
use super::pat::{GateOr, RecoverComma, PARAM_EXPECTED};
use super::ty::{AllowPlus, RecoverQPath, RecoverReturnSign};
use super::{BlockMode, Parser, PathStyle, Restrictions, TokenType};
use super::{SemiColonMode, SeqSep, TokenExpectType};
@ -1729,7 +1729,7 @@ impl<'a> Parser<'a> {
/// The `let` token has already been eaten.
fn parse_let_expr(&mut self, attrs: AttrVec) -> PResult<'a, P<Expr>> {
let lo = self.prev_token.span;
let pat = self.parse_top_pat(GateOr::No)?;
let pat = self.parse_top_pat(GateOr::No, RecoverComma::Yes)?;
self.expect(&token::Eq)?;
let expr = self.with_res(self.restrictions | Restrictions::NO_STRUCT_LITERAL, |this| {
this.parse_assoc_expr_with(1 + prec_let_scrutinee_needs_par(), None.into())
@ -1792,7 +1792,7 @@ impl<'a> Parser<'a> {
_ => None,
};
let pat = self.parse_top_pat(GateOr::Yes)?;
let pat = self.parse_top_pat(GateOr::Yes, RecoverComma::Yes)?;
if !self.eat_keyword(kw::In) {
self.error_missing_in_for_loop();
}
@ -1902,7 +1902,7 @@ impl<'a> Parser<'a> {
pub(super) fn parse_arm(&mut self) -> PResult<'a, Arm> {
let attrs = self.parse_outer_attributes()?;
let lo = self.token.span;
let pat = self.parse_top_pat(GateOr::No)?;
let pat = self.parse_top_pat(GateOr::No, RecoverComma::Yes)?;
let guard = if self.eat_keyword(kw::If) {
let if_span = self.prev_token.span;
let cond = self.parse_expr()?;

1
compiler/rustc_parse/src/parser/mod.rs
View File

@ -12,6 +12,7 @@ mod ty;
use crate::lexer::UnmatchedBrace;
pub use diagnostics::AttemptLocalParseRecovery;
use diagnostics::Error;
pub use pat::OrPatNonterminalMode;
pub use path::PathStyle;
use rustc_ast::ptr::P;

23
compiler/rustc_parse/src/parser/nonterminal.rs
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@ -4,6 +4,7 @@ use rustc_ast_pretty::pprust;
use rustc_errors::PResult;
use rustc_span::symbol::{kw, Ident};
use crate::parser::pat::{GateOr, OrPatNonterminalMode, RecoverComma};
use crate::parser::{FollowedByType, Parser, PathStyle};
impl<'a> Parser<'a> {
@ -11,7 +12,11 @@ impl<'a> Parser<'a> {
///
/// Returning `false` is a *stability guarantee* that such a matcher will *never* begin with that
/// token. Be conservative (return true) if not sure.
pub fn nonterminal_may_begin_with(kind: NonterminalKind, token: &Token) -> bool {
pub fn nonterminal_may_begin_with(
kind: NonterminalKind,
token: &Token,
or_pat_mode: OrPatNonterminalMode,
) -> bool {
/// Checks whether the non-terminal may contain a single (non-keyword) identifier.
fn may_be_ident(nt: &token::Nonterminal) -> bool {
match *nt {
@ -70,6 +75,8 @@ impl<'a> Parser<'a> {
token::ModSep | // path
token::Lt | // path (UFCS constant)
token::BinOp(token::Shl) => true, // path (double UFCS)
// leading vert `|` or-pattern
token::BinOp(token::Or) => matches!(or_pat_mode, OrPatNonterminalMode::TopPat),
token::Interpolated(ref nt) => may_be_ident(nt),
_ => false,
},
@ -86,7 +93,12 @@ impl<'a> Parser<'a> {
}
}
pub fn parse_nonterminal(&mut self, kind: NonterminalKind) -> PResult<'a, Nonterminal> {
/// Parse a non-terminal (e.g. MBE `:pat` or `:ident`).
pub fn parse_nonterminal(
&mut self,
kind: NonterminalKind,
or_pat_mode: OrPatNonterminalMode,
) -> PResult<'a, Nonterminal> {
// Any `Nonterminal` which stores its tokens (currently `NtItem` and `NtExpr`)
// needs to have them force-captured here.
// A `macro_rules!` invocation may pass a captured item/expr to a proc-macro,
@ -130,7 +142,12 @@ impl<'a> Parser<'a> {
}
}
NonterminalKind::Pat => {
let (mut pat, tokens) = self.collect_tokens(|this| this.parse_pat(None))?;
let (mut pat, tokens) = self.collect_tokens(|this| match or_pat_mode {
OrPatNonterminalMode::TopPat => {
this.parse_top_pat(GateOr::Yes, RecoverComma::No)
}
OrPatNonterminalMode::NoTopAlt => this.parse_pat(None),
})?;
// We have have eaten an NtPat, which could already have tokens
if pat.tokens.is_none() {
pat.tokens = tokens;

17
compiler/rustc_parse/src/parser/pat.rs
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@ -26,11 +26,18 @@ pub(super) enum GateOr {
/// Whether or not to recover a `,` when parsing or-patterns.
#[derive(PartialEq, Copy, Clone)]
enum RecoverComma {
pub(super) enum RecoverComma {
Yes,
No,
}
/// Used when parsing a non-terminal (see `parse_nonterminal`) to determine if `:pat` should match
/// `top_pat` or `pat<no_top_alt>`. See issue <https://github.com/rust-lang/rust/pull/78935>.
pub enum OrPatNonterminalMode {
TopPat,
NoTopAlt,
}
impl<'a> Parser<'a> {
/// Parses a pattern.
///
@ -43,13 +50,17 @@ impl<'a> Parser<'a> {
/// Entry point to the main pattern parser.
/// Corresponds to `top_pat` in RFC 2535 and allows or-pattern at the top level.
pub(super) fn parse_top_pat(&mut self, gate_or: GateOr) -> PResult<'a, P<Pat>> {
pub(super) fn parse_top_pat(
&mut self,
gate_or: GateOr,
rc: RecoverComma,
) -> PResult<'a, P<Pat>> {
// Allow a '|' before the pats (RFCs 1925, 2530, and 2535).
let gated_leading_vert = self.eat_or_separator(None) && gate_or == GateOr::Yes;
let leading_vert_span = self.prev_token.span;
// Parse the possibly-or-pattern.
let pat = self.parse_pat_with_or(None, gate_or, RecoverComma::Yes)?;
let pat = self.parse_pat_with_or(None, gate_or, rc)?;
// If we parsed a leading `|` which should be gated,
// and no other gated or-pattern has been parsed thus far,

4
compiler/rustc_parse/src/parser/stmt.rs
View File

@ -1,7 +1,7 @@
use super::attr::DEFAULT_INNER_ATTR_FORBIDDEN;
use super::diagnostics::{AttemptLocalParseRecovery, Error};
use super::expr::LhsExpr;
use super::pat::GateOr;
use super::pat::{GateOr, RecoverComma};
use super::path::PathStyle;
use super::{BlockMode, Parser, Restrictions, SemiColonMode};
use crate::maybe_whole;
@ -185,7 +185,7 @@ impl<'a> Parser<'a> {
/// Parses a local variable declaration.
fn parse_local(&mut self, attrs: AttrVec) -> PResult<'a, P<Local>> {
let lo = self.prev_token.span;
let pat = self.parse_top_pat(GateOr::Yes)?;
let pat = self.parse_top_pat(GateOr::Yes, RecoverComma::Yes)?;
let (err, ty) = if self.eat(&token::Colon) {
// Save the state of the parser before parsing type normally, in case there is a `:`

15
src/test/ui/macros/macro-pat-follow-2018.rs Normal file
View File

@ -0,0 +1,15 @@
// run-pass
// edition:2018
macro_rules! pat_bar {
($p:pat | $p2:pat) => {{
match Some(1u8) {
$p | $p2 => {}
_ => {}
}
}};
}
fn main() {
pat_bar!(Some(1u8) | None);
}

16
src/test/ui/macros/macro-pat-follow.rs
View File

@ -3,29 +3,19 @@ macro_rules! pat_in {
($p:pat in $e:expr) => {{
let mut iter = $e.into_iter();
while let $p = iter.next() {}
}}
}};
}
macro_rules! pat_if {
($p:pat if $e:expr) => {{
match Some(1u8) {
$p if $e => {},
$p if $e => {}
_ => {}
}
}}
}
macro_rules! pat_bar {
($p:pat | $p2:pat) => {{
match Some(1u8) {
$p | $p2 => {},
_ => {}
}
}}
}};
}
fn main() {
pat_in!(Some(_) in 0..10);
pat_if!(Some(x) if x > 0);
pat_bar!(Some(1u8) | None);
}

15
src/test/ui/or-patterns/or-patterns-syntactic-fail-2018.rs Normal file
View File

@ -0,0 +1,15 @@
// Test that :pat doesn't accept top-level or-patterns in edition 2018.
// edition:2018
#![feature(or_patterns)]
fn main() {}
// Test the `pat` macro fragment parser:
macro_rules! accept_pat {
($p:pat) => {};
}
accept_pat!(p | q); //~ ERROR no rules expected the token `|`
accept_pat!(|p| q); //~ ERROR no rules expected the token `|`

20
src/test/ui/or-patterns/or-patterns-syntactic-fail-2018.stderr Normal file
View File

@ -0,0 +1,20 @@
error: no rules expected the token `|`
--> $DIR/or-patterns-syntactic-fail-2018.rs:14:15
|
LL | macro_rules! accept_pat {
| ----------------------- when calling this macro
...
LL | accept_pat!(p | q);
| ^ no rules expected this token in macro call
error: no rules expected the token `|`
--> $DIR/or-patterns-syntactic-fail-2018.rs:15:13
|
LL | macro_rules! accept_pat {
| ----------------------- when calling this macro
...
LL | accept_pat!(|p| q);
| ^ no rules expected this token in macro call
error: aborting due to 2 previous errors

10
src/test/ui/or-patterns/or-patterns-syntactic-fail.rs
View File

@ -5,16 +5,6 @@
fn main() {}
// Test the `pat` macro fragment parser:
macro_rules! accept_pat {
($p:pat) => {}
}
accept_pat!(p | q); //~ ERROR no rules expected the token `|`
accept_pat!(| p | q); //~ ERROR no rules expected the token `|`
// Non-macro tests:
enum E { A, B }
use E::*;

48
src/test/ui/or-patterns/or-patterns-syntactic-fail.stderr
View File

@ -1,53 +1,53 @@
error: an or-pattern parameter must be wrapped in parenthesis
--> $DIR/or-patterns-syntactic-fail.rs:27:13
--> $DIR/or-patterns-syntactic-fail.rs:17:13
|
LL | fn fun1(A | B: E) {}
| ^^^^^ help: wrap the pattern in parenthesis: `(A | B)`
error: a leading `|` is not allowed in a parameter pattern
--> $DIR/or-patterns-syntactic-fail.rs:29:13
--> $DIR/or-patterns-syntactic-fail.rs:19:13
|
LL | fn fun2(| A | B: E) {}
| ^ help: remove the `|`
error: an or-pattern parameter must be wrapped in parenthesis
--> $DIR/or-patterns-syntactic-fail.rs:29:15
--> $DIR/or-patterns-syntactic-fail.rs:19:15
|
LL | fn fun2(| A | B: E) {}
| ^^^^^ help: wrap the pattern in parenthesis: `(A | B)`
error: a leading `|` is only allowed in a top-level pattern
--> $DIR/or-patterns-syntactic-fail.rs:40:11
--> $DIR/or-patterns-syntactic-fail.rs:30:11
|
LL | let ( | A | B) = E::A;
| ^ help: remove the `|`
error: a leading `|` is only allowed in a top-level pattern
--> $DIR/or-patterns-syntactic-fail.rs:41:11
--> $DIR/or-patterns-syntactic-fail.rs:31:11
|
LL | let ( | A | B,) = (E::B,);
| ^ help: remove the `|`
error: a leading `|` is only allowed in a top-level pattern
--> $DIR/or-patterns-syntactic-fail.rs:42:11
--> $DIR/or-patterns-syntactic-fail.rs:32:11
|
LL | let [ | A | B ] = [E::A];
| ^ help: remove the `|`
error: a leading `|` is only allowed in a top-level pattern
--> $DIR/or-patterns-syntactic-fail.rs:43:13
--> $DIR/or-patterns-syntactic-fail.rs:33:13
|
LL | let TS( | A | B );
| ^ help: remove the `|`
error: a leading `|` is only allowed in a top-level pattern
--> $DIR/or-patterns-syntactic-fail.rs:44:17
--> $DIR/or-patterns-syntactic-fail.rs:34:17
|
LL | let NS { f: | A | B };
| ^ help: remove the `|`
error: a leading `|` is only allowed in a top-level pattern
--> $DIR/or-patterns-syntactic-fail.rs:46:11
--> $DIR/or-patterns-syntactic-fail.rs:36:11
|
LL | let ( || A | B) = E::A;
| ^^ help: remove the `||`
@ -55,7 +55,7 @@ LL | let ( || A | B) = E::A;
= note: alternatives in or-patterns are separated with `|`, not `||`
error: a leading `|` is only allowed in a top-level pattern
--> $DIR/or-patterns-syntactic-fail.rs:47:11
--> $DIR/or-patterns-syntactic-fail.rs:37:11
|
LL | let [ || A | B ] = [E::A];
| ^^ help: remove the `||`
@ -63,7 +63,7 @@ LL | let [ || A | B ] = [E::A];
= note: alternatives in or-patterns are separated with `|`, not `||`
error: a leading `|` is only allowed in a top-level pattern
--> $DIR/or-patterns-syntactic-fail.rs:48:13
--> $DIR/or-patterns-syntactic-fail.rs:38:13
|
LL | let TS( || A | B );
| ^^ help: remove the `||`
@ -71,33 +71,15 @@ LL | let TS( || A | B );
= note: alternatives in or-patterns are separated with `|`, not `||`
error: a leading `|` is only allowed in a top-level pattern
--> $DIR/or-patterns-syntactic-fail.rs:49:17
--> $DIR/or-patterns-syntactic-fail.rs:39:17
|
LL | let NS { f: || A | B };
| ^^ help: remove the `||`
|
= note: alternatives in or-patterns are separated with `|`, not `||`
error: no rules expected the token `|`
--> $DIR/or-patterns-syntactic-fail.rs:13:15
|
LL | macro_rules! accept_pat {
| ----------------------- when calling this macro
...
LL | accept_pat!(p | q);
| ^ no rules expected this token in macro call
error: no rules expected the token `|`
--> $DIR/or-patterns-syntactic-fail.rs:14:13
|
LL | macro_rules! accept_pat {
| ----------------------- when calling this macro
...
LL | accept_pat!(| p | q);
| ^ no rules expected this token in macro call
error[E0369]: no implementation for `E | ()`
--> $DIR/or-patterns-syntactic-fail.rs:23:22
--> $DIR/or-patterns-syntactic-fail.rs:13:22
|
LL | let _ = |A | B: E| ();
| ----^ -- ()
@ -107,7 +89,7 @@ LL | let _ = |A | B: E| ();
= note: an implementation of `std::ops::BitOr` might be missing for `E`
error[E0308]: mismatched types
--> $DIR/or-patterns-syntactic-fail.rs:51:36
--> $DIR/or-patterns-syntactic-fail.rs:41:36
|
LL | let recovery_witness: String = 0;
| ------ ^
@ -116,7 +98,7 @@ LL | let recovery_witness: String = 0;
| | help: try using a conversion method: `0.to_string()`
| expected due to this
error: aborting due to 16 previous errors
error: aborting due to 14 previous errors
Some errors have detailed explanations: E0308, E0369.
For more information about an error, try `rustc --explain E0308`.

14
src/test/ui/or-patterns/or-patterns-syntactic-pass-2021.rs Normal file
View File

@ -0,0 +1,14 @@
// Tests that :pat in macros in edition 2021 allows top-level or-patterns.
// run-pass
// ignore-test
// edition:2021
// FIXME(mark-i-m): unignore when 2021 machinery is in place.
macro_rules! accept_pat {
($p:pat) => {};
}
accept_pat!(p | q);
fn main() {}

44
src/test/ui/pattern/or-pattern-macro-pat.rs Normal file
View File

@ -0,0 +1,44 @@
// run-pass
// edition:2021
// ignore-test
// FIXME(mark-i-m): enable this test again when 2021 machinery is available
#![feature(or_patterns)]
use Foo::*;
#[derive(Eq, PartialEq, Debug)]
enum Foo {
A(u64),
B(u64),
C,
D,
}
macro_rules! foo {
($orpat:pat, $val:expr) => {
match $val {
x @ ($orpat) => x, // leading vert would not be allowed in $orpat
_ => B(0xDEADBEEFu64),
}
};
}
macro_rules! bar {
($orpat:pat, $val:expr) => {
match $val {
$orpat => 42, // leading vert allowed here
_ => 0xDEADBEEFu64,
}
};
}
fn main() {
// Test or-pattern.
let y = foo!(A(_)|B(_), A(32));
assert_eq!(y, A(32));
// Leading vert in or-pattern.
let y = bar!(|C| D, C);
assert_eq!(y, 42u64);
}