bjoernager/rust
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Implement edition-based macro pat feature

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mark 2020-12-28 16:57:13 -06:00
parent 2987785df3
commit 40bf3c0f09
12 changed files with 151 additions and 76 deletions
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24
compiler/rustc_expand/src/mbe/macro_parser.rs
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@ -77,9 +77,9 @@ use TokenTreeOrTokenTreeSlice::*;
use crate::mbe::{self, TokenTree};
use rustc_ast::token::{self, DocComment, Nonterminal, Token};
use rustc_parse::parser::{OrPatNonterminalMode, Parser};
use rustc_parse::parser::Parser;
use rustc_session::parse::ParseSess;
use rustc_span::{edition::Edition, symbol::MacroRulesNormalizedIdent};
use rustc_span::symbol::MacroRulesNormalizedIdent;
use smallvec::{smallvec, SmallVec};
@ -419,18 +419,6 @@ 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`.
///
@ -578,14 +566,13 @@ 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(span, _, Some(kind)) => {
TokenTree::MetaVarDecl(_, _, Some(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()))
{
if Parser::nonterminal_may_begin_with(kind, token) {
bb_items.push(item);
}
}
@ -749,8 +736,7 @@ pub(super) fn parse_tt(parser: &mut Cow<'_, Parser<'_>>, ms: &[TokenTree]) -> Na
let match_cur = item.match_cur;
// 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()))
{
let nt = match parser.to_mut().parse_nonterminal(kind) {
Err(mut err) => {
err.span_label(
span,