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Allow : after pat_param #162264

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8175c33
Allow `:` after `pat_param`
coolreader18 Sep 3, 2026
87fe68c
Split NtPatKind::PatParam
coolreader18 Oct 8, 2026
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20 changes: 10 additions & 10 deletions compiler/rustc_ast/src/token.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -101,8 +101,8 @@ impl fmt::Display for MetaVarKind {
MetaVarKind::Item => sym::item,
MetaVarKind::Block => sym::block,
MetaVarKind::Stmt => sym::stmt,
MetaVarKind::Pat(PatParam { inferred: true } | PatWithOr) => sym::pat,
MetaVarKind::Pat(PatParam { inferred: false }) => sym::pat_param,
MetaVarKind::Pat(Pat2018 | PatWithOr) => sym::pat,
MetaVarKind::Pat(PatParam) => sym::pat_param,
MetaVarKind::Expr { kind: Expr2021 { inferred: true } | Expr, .. } => sym::expr,
MetaVarKind::Expr { kind: Expr2021 { inferred: false }, .. } => sym::expr_2021,
MetaVarKind::Ty { .. } => sym::ty,
Expand Down Expand Up @@ -1119,10 +1119,10 @@ pub fn ident_of_kind_is_reserved(id: sp::Ident, kind: IdentKind) -> bool {
pub enum NtPatKind {
// Matches or-patterns. Was written using `pat` in edition 2021 or later.
PatWithOr,
// Doesn't match or-patterns.
// - `inferred`: was written using `pat` in edition 2015 or 2018.
// - `!inferred`: was written using `pat_param`.
PatParam { inferred: bool },
// Doesn't match or-patterns. Was written using `pat_param`.
PatParam,
// Doesn't match or-patterns. Was written using `pat` in edition 2015 or 2018.
Pat2018,
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, Encodable, Decodable, Hash, StableHash)]
Expand Down Expand Up @@ -1170,10 +1170,10 @@ impl NonterminalKind {
if edition().at_least_rust_2021() {
NonterminalKind::Pat(PatWithOr)
} else {
NonterminalKind::Pat(PatParam { inferred: true })
NonterminalKind::Pat(Pat2018)
}
}
sym::pat_param => NonterminalKind::Pat(PatParam { inferred: false }),
sym::pat_param => NonterminalKind::Pat(PatParam),
sym::expr => {
if edition().at_least_rust_2024() {
NonterminalKind::Expr(Expr)
Expand All @@ -1200,8 +1200,8 @@ impl NonterminalKind {
NonterminalKind::Item => sym::item,
NonterminalKind::Block => sym::block,
NonterminalKind::Stmt => sym::stmt,
NonterminalKind::Pat(PatParam { inferred: true } | PatWithOr) => sym::pat,
NonterminalKind::Pat(PatParam { inferred: false }) => sym::pat_param,
NonterminalKind::Pat(Pat2018 | PatWithOr) => sym::pat,
NonterminalKind::Pat(PatParam) => sym::pat_param,
NonterminalKind::Expr(Expr2021 { inferred: true } | Expr) => sym::expr,
NonterminalKind::Expr(Expr2021 { inferred: false }) => sym::expr_2021,
NonterminalKind::Ty => sym::ty,
Expand Down
25 changes: 21 additions & 4 deletions compiler/rustc_expand/src/mbe/macro_rules.rs
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Expand Up @@ -1583,7 +1583,7 @@ fn check_matcher_core<'tt>(
// the macro when compiling another crate that is using the
// macro. (See #86567.)
if is_defined_in_current_crate(node_id)
&& matches!(kind, NonterminalKind::Pat(PatParam { inferred: true }))
&& matches!(kind, NonterminalKind::Pat(Pat2018))
&& matches!(
next_token,
TokenTree::Token(token) if *token == token::Or
Expand All @@ -1593,7 +1593,7 @@ fn check_matcher_core<'tt>(
let suggestion = quoted_tt_to_string(&TokenTree::MetaVarDecl {
span,
name,
kind: NonterminalKind::Pat(PatParam { inferred: false }),
kind: NonterminalKind::Pat(PatParam),
});
sess.psess.buffer_lint(
RUST_2021_INCOMPATIBLE_OR_PATTERNS,
Expand Down Expand Up @@ -1629,11 +1629,13 @@ fn check_matcher_core<'tt>(
if kind == NonterminalKind::Pat(PatWithOr)
&& sess.psess.edition.at_least_rust_2021()
&& next_token.is_token(&token::Or)
|| matches!(kind, NonterminalKind::Pat(PatWithOr | Pat2018))
&& next_token.is_token(&token::Colon)
{
let suggestion = quoted_tt_to_string(&TokenTree::MetaVarDecl {
span,
name,
kind: NonterminalKind::Pat(PatParam { inferred: false }),
kind: NonterminalKind::Pat(PatParam),
});
err.span_suggestion(
span,
Expand Down Expand Up @@ -1745,7 +1747,7 @@ fn is_in_follow(tok: &mbe::TokenTree, kind: NonterminalKind) -> IsInFollow {
_ => IsInFollow::No(TOKENS),
}
}
NonterminalKind::Pat(PatParam { .. }) => {
NonterminalKind::Pat(Pat2018) => {
const TOKENS: &[&str] = &["`=>`", "`,`", "`=`", "`|`", "`if`", "`if let`", "`in`"];
match tok {
TokenTree::Token(token) => match token.kind {
Expand All @@ -1759,6 +1761,21 @@ fn is_in_follow(tok: &mbe::TokenTree, kind: NonterminalKind) -> IsInFollow {
_ => IsInFollow::No(TOKENS),
}
}
NonterminalKind::Pat(PatParam) => {
const TOKENS: &[&str] =
&["`=>`", "`,`", "`=`", "`|`", "`:`", "`if`", "`if let`", "`in`"];
match tok {
TokenTree::Token(token) => match token.kind {
FatArrow | Comma | Eq | Or | Colon => IsInFollow::Yes,
Ident(kw::If | kw::In, IdentKind::Normal | IdentKind::ForcedKeyword) => {
IsInFollow::Yes
}
_ => IsInFollow::No(TOKENS),
},
TokenTree::MetaVarDecl { kind: NonterminalKind::Guard, .. } => IsInFollow::Yes,
_ => IsInFollow::No(TOKENS),
}
}
NonterminalKind::Pat(PatWithOr) => {
const TOKENS: &[&str] = &["`=>`", "`,`", "`=`", "`if`", "`if let`", "`in`"];
match tok {
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_parse/src/parser/nonterminal.rs
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Expand Up @@ -148,7 +148,7 @@ impl<'a> Parser<'a> {
NonterminalKind::Pat(pat_kind) => Ok(ParseNtResult::Pat(
self.collect_tokens_no_attrs(|this| {
match pat_kind {
PatParam { .. } => this.parse_pat_no_top_alt(None, None),
PatParam | Pat2018 => this.parse_pat_no_top_alt(None, None),
PatWithOr => this.parse_pat_no_top_guard(
None,
RecoverComma::No,
Expand Down
6 changes: 2 additions & 4 deletions compiler/rustc_parse/src/parser/pat.rs
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Expand Up @@ -698,7 +698,7 @@ impl<'a> Parser<'a> {
fn eat_metavar_pat(&mut self) -> Option<Pat> {
// Must try both kinds of pattern nonterminals.
if let Some(pat) = self.eat_metavar_seq_with_matcher(
|mv_kind| matches!(mv_kind, MetaVarKind::Pat(PatParam { .. })),
|mv_kind| matches!(mv_kind, MetaVarKind::Pat(PatParam | Pat2018)),
|this| this.parse_pat_no_top_alt(None, None),
) {
Some(pat)
Expand Down Expand Up @@ -733,9 +733,7 @@ impl<'a> Parser<'a> {
let mut lo = self.token.span;

if self.token.is_keyword(kw::Let)
&& self.look_ahead(1, |tok| {
tok.can_begin_pattern(token::NtPatKind::PatParam { inferred: false })
})
&& self.look_ahead(1, |tok| tok.can_begin_pattern(PatParam))
{
self.bump();
// Trim extra space after the `let`
Expand Down
4 changes: 1 addition & 3 deletions compiler/rustc_parse/src/parser/path.rs
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Expand Up @@ -388,9 +388,7 @@ impl<'a> Parser<'a> {
&& prev_token_before_parsing == token::PathSep
&& (style == PathStyle::Expr && self.token.can_begin_expr()
|| style == PathStyle::Pat
&& self.token.can_begin_pattern(token::NtPatKind::PatParam {
inferred: false,
}))
&& self.token.can_begin_pattern(token::NtPatKind::PatParam))
{
snapshot = Some(self.create_snapshot_for_diagnostic());
}
Expand Down
2 changes: 1 addition & 1 deletion src/tools/rustfmt/src/parse/macros/mod.rs
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Expand Up @@ -61,7 +61,7 @@ fn parse_macro_arg<'a, 'b: 'a>(parser: &'a mut Parser<'b>) -> Option<MacroArg> {
);
parse_macro_arg!(
Pat,
NonterminalKind::Pat(PatParam { inferred: false }),
NonterminalKind::Pat(PatParam),
|parser: &mut Parser<'b>| parser.parse_pat_no_top_alt(None, None),
|x: ast::Pat| Some(Box::new(x))
);
Expand Down
22 changes: 22 additions & 0 deletions tests/ui/macros/macro-follow.rs
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Expand Up @@ -27,6 +27,28 @@ macro_rules! follow_pat {
($p:pat $i:item) => {}; //~ERROR `$p:pat` is followed by `$i:item`
($p:pat $m:meta) => {}; //~ERROR `$p:pat` is followed by `$m:meta`
}
// FOLLOW(pat_param) = {FOLLOW(pat), Colon[, Or]}
// optional inclusion of `Or` depends on the edition; this is tested separately,
// in `macro-pat-pattern-followed-by-or.rs` / `macro-pat-pattern-followed-by-or-in-2021.rs`
macro_rules! follow_pat {
($p:pat_param ()) => {}; //~ERROR `$p:pat_param` is followed by `(`
($p:pat_param []) => {}; //~ERROR `$p:pat_param` is followed by `[`
($p:pat_param {}) => {}; //~ERROR `$p:pat_param` is followed by `{`
($p:pat_param :) => {}; // ok
($p:pat_param >) => {}; //~ERROR `$p:pat_param` is followed by `>`
($p:pat_param +) => {}; //~ERROR `$p:pat_param` is followed by `+`
($p:pat_param ident) => {}; //~ERROR `$p:pat_param` is followed by `ident`
($p:pat_param $q:pat) => {}; //~ERROR `$p:pat_param` is followed by `$q:pat`
($p:pat_param $e:expr) => {}; //~ERROR `$p:pat_param` is followed by `$e:expr`
($p:pat_param $t:ty) => {}; //~ERROR `$p:pat_param` is followed by `$t:ty`
($p:pat_param $s:stmt) => {}; //~ERROR `$p:pat_param` is followed by `$s:stmt`
($p:pat_param $q:path) => {}; //~ERROR `$p:pat_param` is followed by `$q:path`
($p:pat_param $b:block) => {}; //~ERROR `$p:pat_param` is followed by `$b:block`
($p:pat_param $i:ident) => {}; //~ERROR `$p:pat_param` is followed by `$i:ident`
($p:pat_param $t:tt) => {}; //~ERROR `$p:pat_param` is followed by `$t:tt`
($p:pat_param $i:item) => {}; //~ERROR `$p:pat_param` is followed by `$i:item`
($p:pat_param $m:meta) => {}; //~ERROR `$p:pat_param` is followed by `$m:meta`
}
// FOLLOW(expr) = {FatArrow, Comma, Semicolon}
macro_rules! follow_expr {
($e:expr ()) => {}; //~ERROR `$e:expr` is followed by `(`
Expand Down
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