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Auto merge of #123865 - eholk:expr_2021, r=fmease

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Update `expr` matcher for Edition 2024 and add `expr_2021` nonterminal

This commit adds a new nonterminal `expr_2021` in macro patterns, and `expr_fragment_specifier_2024` feature flag.

This change also updates `expr` so that on Edition 2024 it will also match `const { ... }` blocks, while `expr_2021` preserves the current behavior of `expr`, matching expressions without `const` blocks.

Joint work with `@vincenzopalazzo.`

Issue #123742
This commit is contained in:
bors 2024-05-17 21:54:14 +00:00
commit 9b75a43881
13 changed files with 204 additions and 24 deletions
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2
compiler/rustc_expand/src/mbe/macro_rules.rs
View file

@ -1290,7 +1290,7 @@ fn is_in_follow(tok: &mbe::TokenTree, kind: NonterminalKind) -> IsInFollow {
// maintain
IsInFollow::Yes
}
NonterminalKind::Stmt | NonterminalKind::Expr => {
NonterminalKind::Stmt | NonterminalKind::Expr | NonterminalKind::Expr2021 => {
const TOKENS: &[&str] = &["`=>`", "`,`", "`;`"];
match tok {
TokenTree::Token(token) => match token.kind {

71
compiler/rustc_expand/src/mbe/quoted.rs
View file

@ -16,6 +16,10 @@ use rustc_span::Span;
const VALID_FRAGMENT_NAMES_MSG: &str = "valid fragment specifiers are \
`ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, \
`literal`, `path`, `meta`, `tt`, `item` and `vis`";
const VALID_FRAGMENT_NAMES_MSG_2021: &str = "valid fragment specifiers are \
`ident`, `block`, `stmt`, `expr`, `expr_2021`, `pat`, \
`ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, \
`item` and `vis`";
/// Takes a `tokenstream::TokenStream` and returns a `Vec<self::TokenTree>`. Specifically, this
/// takes a generic `TokenStream`, such as is used in the rest of the compiler, and returns a
@ -63,35 +67,60 @@ pub(super) fn parse(
Some(tokenstream::TokenTree::Token(token, _)) => match token.ident() {
Some((fragment, _)) => {
let span = token.span.with_lo(start_sp.lo());
let edition = || {
// FIXME(#85708) - once we properly decode a foreign
// crate's `SyntaxContext::root`, then we can replace
// this with just `span.edition()`. A
// `SyntaxContext::root()` from the current crate will
// have the edition of the current crate, and a
// `SyntaxContext::root()` from a foreign crate will
// have the edition of that crate (which we manually
// retrieve via the `edition` parameter).
if !span.from_expansion() {
edition
} else {
span.edition()
}
};
let kind =
token::NonterminalKind::from_symbol(fragment.name, || {
// FIXME(#85708) - once we properly decode a foreign
// crate's `SyntaxContext::root`, then we can replace
// this with just `span.edition()`. A
// `SyntaxContext::root()` from the current crate will
// have the edition of the current crate, and a
// `SyntaxContext::root()` from a foreign crate will
// have the edition of that crate (which we manually
// retrieve via the `edition` parameter).
if !span.from_expansion() {
edition
} else {
span.edition()
}
})
.unwrap_or_else(
|| {
token::NonterminalKind::from_symbol(fragment.name, edition)
.unwrap_or_else(|| {
let help = match fragment.name {
sym::expr_2021 => {
format!(
"fragment specifier `expr_2021` \
requires Rust 2021 or later\n\
{VALID_FRAGMENT_NAMES_MSG}"
)
}
_ if edition().at_least_rust_2021()
&& features
.expr_fragment_specifier_2024 =>
{
VALID_FRAGMENT_NAMES_MSG_2021.into()
}
_ => VALID_FRAGMENT_NAMES_MSG.into(),
};
sess.dcx().emit_err(
errors::InvalidFragmentSpecifier {
span,
fragment,
help: VALID_FRAGMENT_NAMES_MSG.into(),
help,
},
);
token::NonterminalKind::Ident
},
);
});
if kind == token::NonterminalKind::Expr2021
&& !features.expr_fragment_specifier_2024
{
rustc_session::parse::feature_err(
sess,
sym::expr_fragment_specifier_2024,
span,
"fragment specifier `expr_2021` is unstable",
)
.emit();
}
result.push(TokenTree::MetaVarDecl(span, ident, Some(kind)));
continue;
}