Skip to content

Commit e2aa38e

Browse files
nnethercotennethercote
committed
Rework pattern and expression nonterminal kinds.
Merge `PatParam`/`PatWithOr`, and `Expr`/`Expr2021`, for a few reasons. - It's conceptually nice, because the two pattern kinds and the two expression kinds are very similar. - With expressions in particular, there are several places where both expression kinds get the same treatment. - It removes one unreachable match arm. - Most importantly, for #124141 I will need to introduce a new type `MetaVarKind` that is very similar to `NonterminalKind`, but records a couple of extra fields for expression metavars. It's nicer to have a single `MetaVarKind::Expr` expression variant to hold those extra fields instead of duplicating them across two variants `MetaVarKind::{Expr,Expr2021}`. And then it makes sense for patterns to be treated the same way, and for `NonterminalKind` to also be treated the same way. I also clarified the comments, because I have long found them a little hard to understand.
1 parent 70fa67c commit e2aa38e

File tree

5 files changed

+71
-60
lines changed

5 files changed

+71
-60
lines changed

‎compiler/rustc_ast/src/token.rs

+44-29
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,8 @@
11
pub use BinOpToken::*;
22
pub use LitKind::*;
33
pub use Nonterminal::*;
4+
pub use NtExprKind::*;
5+
pub use NtPatKind::*;
46
pub use TokenKind::*;
57

68
use crate::ast;
@@ -871,6 +873,27 @@ impl PartialEq<TokenKind> for Token {
871873
}
872874
}
873875

876+
#[derive(Debug, Copy, Clone, PartialEq, Eq, Encodable, Decodable)]
877+
pub enum NtPatKind {
878+
// Matches or-patterns. Was written using `pat` in edition 2021 or later.
879+
PatWithOr,
880+
// Doesn't match or-patterns.
881+
// - `inferred`: was written using `pat` in edition 2015 or 2018.
882+
// - `!inferred`: was written using `pat_param`.
883+
PatParam { inferred: bool },
884+
}
885+
886+
#[derive(Debug, Copy, Clone, PartialEq, Eq, Encodable, Decodable)]
887+
pub enum NtExprKind {
888+
// Matches expressions using the post-edition 2024. Was written using
889+
// `expr` in edition 2024 or later.
890+
Expr,
891+
// Matches expressions using the pre-edition 2024 rules.
892+
// - `inferred`: was written using `expr` in edition 2021 or earlier.
893+
// - `!inferred`: was written using `expr_2021`.
894+
Expr2021 { inferred: bool },
895+
}
896+
874897
#[derive(Clone, Encodable, Decodable)]
875898
/// For interpolation during macro expansion.
876899
pub enum Nonterminal {
@@ -892,19 +915,8 @@ pub enum NonterminalKind {
892915
Item,
893916
Block,
894917
Stmt,
895-
PatParam {
896-
/// Keep track of whether the user used `:pat_param` or `:pat` and we inferred it from the
897-
/// edition of the span. This is used for diagnostics.
898-
inferred: bool,
899-
},
900-
PatWithOr,
901-
Expr,
902-
/// Matches an expression using the rules from edition 2021 and earlier.
903-
Expr2021 {
904-
/// Keep track of whether the user used `:expr` or `:expr_2021` and we inferred it from the
905-
/// edition of the span. This is used for diagnostics AND feature gating.
906-
inferred: bool,
907-
},
918+
Pat(NtPatKind),
919+
Expr(NtExprKind),
908920
Ty,
909921
Ident,
910922
Lifetime,
@@ -926,20 +938,22 @@ impl NonterminalKind {
926938
sym::item => NonterminalKind::Item,
927939
sym::block => NonterminalKind::Block,
928940
sym::stmt => NonterminalKind::Stmt,
929-
sym::pat => match edition() {
930-
Edition::Edition2015 | Edition::Edition2018 => {
931-
NonterminalKind::PatParam { inferred: true }
941+
sym::pat => {
942+
if edition().at_least_rust_2021() {
943+
NonterminalKind::Pat(PatWithOr)
944+
} else {
945+
NonterminalKind::Pat(PatParam { inferred: true })
932946
}
933-
Edition::Edition2021 | Edition::Edition2024 => NonterminalKind::PatWithOr,
934-
},
935-
sym::pat_param => NonterminalKind::PatParam { inferred: false },
936-
sym::expr => match edition() {
937-
Edition::Edition2015 | Edition::Edition2018 | Edition::Edition2021 => {
938-
NonterminalKind::Expr2021 { inferred: true }
947+
}
948+
sym::pat_param => NonterminalKind::Pat(PatParam { inferred: false }),
949+
sym::expr => {
950+
if edition().at_least_rust_2024() {
951+
NonterminalKind::Expr(Expr)
952+
} else {
953+
NonterminalKind::Expr(Expr2021 { inferred: true })
939954
}
940-
Edition::Edition2024 => NonterminalKind::Expr,
941-
},
942-
sym::expr_2021 => NonterminalKind::Expr2021 { inferred: false },
955+
}
956+
sym::expr_2021 => NonterminalKind::Expr(Expr2021 { inferred: false }),
943957
sym::ty => NonterminalKind::Ty,
944958
sym::ident => NonterminalKind::Ident,
945959
sym::lifetime => NonterminalKind::Lifetime,
@@ -951,15 +965,16 @@ impl NonterminalKind {
951965
_ => return None,
952966
})
953967
}
968+
954969
fn symbol(self) -> Symbol {
955970
match self {
956971
NonterminalKind::Item => sym::item,
957972
NonterminalKind::Block => sym::block,
958973
NonterminalKind::Stmt => sym::stmt,
959-
NonterminalKind::PatParam { inferred: false } => sym::pat_param,
960-
NonterminalKind::PatParam { inferred: true } | NonterminalKind::PatWithOr => sym::pat,
961-
NonterminalKind::Expr | NonterminalKind::Expr2021 { inferred: true } => sym::expr,
962-
NonterminalKind::Expr2021 { inferred: false } => sym::expr_2021,
974+
NonterminalKind::Pat(PatParam { inferred: true } | PatWithOr) => sym::pat,
975+
NonterminalKind::Pat(PatParam { inferred: false }) => sym::pat_param,
976+
NonterminalKind::Expr(Expr2021 { inferred: true } | Expr) => sym::expr,
977+
NonterminalKind::Expr(Expr2021 { inferred: false }) => sym::expr_2021,
963978
NonterminalKind::Ty => sym::ty,
964979
NonterminalKind::Ident => sym::ident,
965980
NonterminalKind::Lifetime => sym::lifetime,

‎compiler/rustc_expand/src/mbe/macro_rules.rs

+10-10
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,9 @@ use crate::mbe::transcribe::transcribe;
1010

1111
use ast::token::IdentIsRaw;
1212
use rustc_ast as ast;
13-
use rustc_ast::token::{self, Delimiter, NonterminalKind, Token, TokenKind, TokenKind::*};
13+
use rustc_ast::token::{
14+
self, Delimiter, NonterminalKind, NtPatKind::*, Token, TokenKind, TokenKind::*,
15+
};
1416
use rustc_ast::tokenstream::{DelimSpan, TokenStream};
1517
use rustc_ast::{NodeId, DUMMY_NODE_ID};
1618
use rustc_ast_pretty::pprust;
@@ -1145,7 +1147,7 @@ fn check_matcher_core<'tt>(
11451147
// Macros defined in the current crate have a real node id,
11461148
// whereas macros from an external crate have a dummy id.
11471149
if def.id != DUMMY_NODE_ID
1148-
&& matches!(kind, NonterminalKind::PatParam { inferred: true })
1150+
&& matches!(kind, NonterminalKind::Pat(PatParam { inferred: true }))
11491151
&& matches!(
11501152
next_token,
11511153
TokenTree::Token(token) if token.kind == BinOp(token::BinOpToken::Or)
@@ -1155,7 +1157,7 @@ fn check_matcher_core<'tt>(
11551157
let suggestion = quoted_tt_to_string(&TokenTree::MetaVarDecl(
11561158
span,
11571159
name,
1158-
Some(NonterminalKind::PatParam { inferred: false }),
1160+
Some(NonterminalKind::Pat(PatParam { inferred: false })),
11591161
));
11601162
sess.psess.buffer_lint(
11611163
RUST_2021_INCOMPATIBLE_OR_PATTERNS,
@@ -1188,14 +1190,14 @@ fn check_matcher_core<'tt>(
11881190
);
11891191
err.span_label(sp, format!("not allowed after `{kind}` fragments"));
11901192

1191-
if kind == NonterminalKind::PatWithOr
1193+
if kind == NonterminalKind::Pat(PatWithOr)
11921194
&& sess.psess.edition.at_least_rust_2021()
11931195
&& next_token.is_token(&BinOp(token::BinOpToken::Or))
11941196
{
11951197
let suggestion = quoted_tt_to_string(&TokenTree::MetaVarDecl(
11961198
span,
11971199
name,
1198-
Some(NonterminalKind::PatParam { inferred: false }),
1200+
Some(NonterminalKind::Pat(PatParam { inferred: false })),
11991201
));
12001202
err.span_suggestion(
12011203
span,
@@ -1295,9 +1297,7 @@ fn is_in_follow(tok: &mbe::TokenTree, kind: NonterminalKind) -> IsInFollow {
12951297
// maintain
12961298
IsInFollow::Yes
12971299
}
1298-
NonterminalKind::Stmt
1299-
| NonterminalKind::Expr
1300-
| NonterminalKind::Expr2021 { inferred: _ } => {
1300+
NonterminalKind::Stmt | NonterminalKind::Expr(_) => {
13011301
const TOKENS: &[&str] = &["`=>`", "`,`", "`;`"];
13021302
match tok {
13031303
TokenTree::Token(token) => match token.kind {
@@ -1307,7 +1307,7 @@ fn is_in_follow(tok: &mbe::TokenTree, kind: NonterminalKind) -> IsInFollow {
13071307
_ => IsInFollow::No(TOKENS),
13081308
}
13091309
}
1310-
NonterminalKind::PatParam { .. } => {
1310+
NonterminalKind::Pat(PatParam { .. }) => {
13111311
const TOKENS: &[&str] = &["`=>`", "`,`", "`=`", "`|`", "`if`", "`in`"];
13121312
match tok {
13131313
TokenTree::Token(token) => match token.kind {
@@ -1320,7 +1320,7 @@ fn is_in_follow(tok: &mbe::TokenTree, kind: NonterminalKind) -> IsInFollow {
13201320
_ => IsInFollow::No(TOKENS),
13211321
}
13221322
}
1323-
NonterminalKind::PatWithOr => {
1323+
NonterminalKind::Pat(PatWithOr) => {
13241324
const TOKENS: &[&str] = &["`=>`", "`,`", "`=`", "`if`", "`in`"];
13251325
match tok {
13261326
TokenTree::Token(token) => match token.kind {

‎compiler/rustc_expand/src/mbe/quoted.rs

+2-2
Original file line numberDiff line numberDiff line change
@@ -2,7 +2,7 @@ use crate::errors;
22
use crate::mbe::macro_parser::count_metavar_decls;
33
use crate::mbe::{Delimited, KleeneOp, KleeneToken, MetaVarExpr, SequenceRepetition, TokenTree};
44

5-
use rustc_ast::token::{self, Delimiter, IdentIsRaw, NonterminalKind, Token};
5+
use rustc_ast::token::{self, Delimiter, IdentIsRaw, NonterminalKind, NtExprKind::*, Token};
66
use rustc_ast::{tokenstream, NodeId};
77
use rustc_ast_pretty::pprust;
88
use rustc_feature::Features;
@@ -109,7 +109,7 @@ pub(super) fn parse(
109109
});
110110
NonterminalKind::Ident
111111
});
112-
if kind == (NonterminalKind::Expr2021 { inferred: false })
112+
if kind == NonterminalKind::Expr(Expr2021 { inferred: false })
113113
&& !features.expr_fragment_specifier_2024
114114
{
115115
rustc_session::parse::feature_err(

‎compiler/rustc_parse/src/parser/nonterminal.rs

+12-16
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,7 @@
11
use rustc_ast::ptr::P;
2-
use rustc_ast::token::{self, Delimiter, Nonterminal::*, NonterminalKind, Token};
2+
use rustc_ast::token::{
3+
self, Delimiter, Nonterminal::*, NonterminalKind, NtExprKind::*, NtPatKind::*, Token,
4+
};
35
use rustc_ast::HasTokens;
46
use rustc_ast_pretty::pprust;
57
use rustc_data_structures::sync::Lrc;
@@ -36,14 +38,14 @@ impl<'a> Parser<'a> {
3638
}
3739

3840
match kind {
39-
NonterminalKind::Expr2021 { inferred: _ } => {
41+
NonterminalKind::Expr(Expr2021 { .. }) => {
4042
token.can_begin_expr()
4143
// This exception is here for backwards compatibility.
4244
&& !token.is_keyword(kw::Let)
4345
// This exception is here for backwards compatibility.
4446
&& !token.is_keyword(kw::Const)
4547
}
46-
NonterminalKind::Expr => {
48+
NonterminalKind::Expr(Expr) => {
4749
token.can_begin_expr()
4850
// This exception is here for backwards compatibility.
4951
&& !token.is_keyword(kw::Let)
@@ -74,7 +76,7 @@ impl<'a> Parser<'a> {
7476
token::Interpolated(nt) => may_be_ident(nt),
7577
_ => false,
7678
},
77-
NonterminalKind::PatParam { .. } | NonterminalKind::PatWithOr => match &token.kind {
79+
NonterminalKind::Pat(pat_kind) => match &token.kind {
7880
// box, ref, mut, and other identifiers (can stricten)
7981
token::Ident(..) | token::NtIdent(..) |
8082
token::OpenDelim(Delimiter::Parenthesis) | // tuple pattern
@@ -89,7 +91,7 @@ impl<'a> Parser<'a> {
8991
token::Lt | // path (UFCS constant)
9092
token::BinOp(token::Shl) => true, // path (double UFCS)
9193
// leading vert `|` or-pattern
92-
token::BinOp(token::Or) => matches!(kind, NonterminalKind::PatWithOr),
94+
token::BinOp(token::Or) => matches!(pat_kind, PatWithOr),
9395
token::Interpolated(nt) => may_be_ident(nt),
9496
_ => false,
9597
},
@@ -135,31 +137,25 @@ impl<'a> Parser<'a> {
135137
.create_err(UnexpectedNonterminal::Statement(self.token.span)));
136138
}
137139
},
138-
NonterminalKind::PatParam { .. } | NonterminalKind::PatWithOr => {
139-
NtPat(self.collect_tokens_no_attrs(|this| match kind {
140-
NonterminalKind::PatParam { .. } => this.parse_pat_no_top_alt(None, None),
141-
NonterminalKind::PatWithOr => this.parse_pat_allow_top_alt(
140+
NonterminalKind::Pat(pat_kind) => {
141+
NtPat(self.collect_tokens_no_attrs(|this| match pat_kind {
142+
PatParam { .. } => this.parse_pat_no_top_alt(None, None),
143+
PatWithOr => this.parse_pat_allow_top_alt(
142144
None,
143145
RecoverComma::No,
144146
RecoverColon::No,
145147
CommaRecoveryMode::EitherTupleOrPipe,
146148
),
147-
_ => unreachable!(),
148149
})?)
149150
}
150-
151-
NonterminalKind::Expr | NonterminalKind::Expr2021 { inferred: _ } => {
152-
NtExpr(self.parse_expr_force_collect()?)
153-
}
151+
NonterminalKind::Expr(_) => NtExpr(self.parse_expr_force_collect()?),
154152
NonterminalKind::Literal => {
155153
// The `:literal` matcher does not support attributes
156154
NtLiteral(self.collect_tokens_no_attrs(|this| this.parse_literal_maybe_minus())?)
157155
}
158-
159156
NonterminalKind::Ty => {
160157
NtTy(self.collect_tokens_no_attrs(|this| this.parse_ty_no_question_mark_recover())?)
161158
}
162-
163159
// this could be handled like a token, since it is one
164160
NonterminalKind::Ident => {
165161
return if let Some((ident, is_raw)) = get_macro_ident(&self.token) {

‎src/tools/rustfmt/src/parse/macros/mod.rs

+3-3
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
use rustc_ast::token::{Delimiter, NonterminalKind, TokenKind};
1+
use rustc_ast::token::{Delimiter, NonterminalKind, NtExprKind::*, NtPatKind::*, TokenKind};
22
use rustc_ast::tokenstream::TokenStream;
33
use rustc_ast::{ast, ptr};
44
use rustc_parse::parser::{ForceCollect, Parser, Recovery};
@@ -48,7 +48,7 @@ fn parse_macro_arg<'a, 'b: 'a>(parser: &'a mut Parser<'b>) -> Option<MacroArg> {
4848

4949
parse_macro_arg!(
5050
Expr,
51-
NonterminalKind::Expr,
51+
NonterminalKind::Expr(Expr),
5252
|parser: &mut Parser<'b>| parser.parse_expr(),
5353
|x: ptr::P<ast::Expr>| Some(x)
5454
);
@@ -60,7 +60,7 @@ fn parse_macro_arg<'a, 'b: 'a>(parser: &'a mut Parser<'b>) -> Option<MacroArg> {
6060
);
6161
parse_macro_arg!(
6262
Pat,
63-
NonterminalKind::PatParam { inferred: false },
63+
NonterminalKind::Pat(PatParam { inferred: false }),
6464
|parser: &mut Parser<'b>| parser.parse_pat_no_top_alt(None, None),
6565
|x: ptr::P<ast::Pat>| Some(x)
6666
);

0 commit comments

Comments
 (0)