From 3eba6c18d435fbbdbb46ebd1b2f9bd565daa190c Mon Sep 17 00:00:00 2001 From: Mazdak Farrokhzad Date: Sun, 29 Sep 2019 06:21:20 +0200 Subject: syntax: recover trailing `|` in or-patterns. --- src/libsyntax/parse/parser/pat.rs | 105 ++++++++++++++++++++++++++++---------- 1 file changed, 79 insertions(+), 26 deletions(-) (limited to 'src/libsyntax/parse/parser') diff --git a/src/libsyntax/parse/parser/pat.rs b/src/libsyntax/parse/parser/pat.rs index de72f1c4d49..7eb2a73a11a 100644 --- a/src/libsyntax/parse/parser/pat.rs +++ b/src/libsyntax/parse/parser/pat.rs @@ -18,6 +18,8 @@ type Expected = Option<&'static str>; /// `Expected` for function and lambda parameter patterns. pub(super) const PARAM_EXPECTED: Expected = Some("parameter name"); +const WHILE_PARSING_OR_MSG: &str = "while parsing this or-pattern starting here"; + /// Whether or not an or-pattern should be gated when occurring in the current context. #[derive(PartialEq)] pub enum GateOr { Yes, No } @@ -40,7 +42,7 @@ impl<'a> Parser<'a> { /// 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> { // Allow a '|' before the pats (RFCs 1925, 2530, and 2535). - let gated_leading_vert = self.eat_or_separator() && gate_or == GateOr::Yes; + let gated_leading_vert = self.eat_or_separator(None) && gate_or == GateOr::Yes; let leading_vert_span = self.prev_span; // Parse the possibly-or-pattern. @@ -63,7 +65,7 @@ impl<'a> Parser<'a> { /// Parse the pattern for a function or function pointer parameter. /// Special recovery is provided for or-patterns and leading `|`. pub(super) fn parse_fn_param_pat(&mut self) -> PResult<'a, P> { - self.recover_leading_vert("not allowed in a parameter pattern"); + self.recover_leading_vert(None, "not allowed in a parameter pattern"); let pat = self.parse_pat_with_or(PARAM_EXPECTED, GateOr::No, RecoverComma::No)?; if let PatKind::Or(..) = &pat.kind { @@ -90,7 +92,7 @@ impl<'a> Parser<'a> { gate_or: GateOr, rc: RecoverComma, ) -> PResult<'a, P> { - // Parse the first pattern. + // Parse the first pattern (`p_0`). let first_pat = self.parse_pat(expected)?; self.maybe_recover_unexpected_comma(first_pat.span, rc)?; @@ -100,11 +102,12 @@ impl<'a> Parser<'a> { return Ok(first_pat) } + // Parse the patterns `p_1 | ... | p_n` where `n > 0`. let lo = first_pat.span; let mut pats = vec![first_pat]; - while self.eat_or_separator() { + while self.eat_or_separator(Some(lo)) { let pat = self.parse_pat(expected).map_err(|mut err| { - err.span_label(lo, "while parsing this or-pattern starting here"); + err.span_label(lo, WHILE_PARSING_OR_MSG); err })?; self.maybe_recover_unexpected_comma(pat.span, rc)?; @@ -122,11 +125,15 @@ impl<'a> Parser<'a> { /// Eat the or-pattern `|` separator. /// If instead a `||` token is encountered, recover and pretend we parsed `|`. - fn eat_or_separator(&mut self) -> bool { + fn eat_or_separator(&mut self, lo: Option) -> bool { + if self.recover_trailing_vert(lo) { + return false; + } + match self.token.kind { token::OrOr => { // Found `||`; Recover and pretend we parsed `|`. - self.ban_unexpected_or_or(); + self.ban_unexpected_or_or(lo); self.bump(); true } @@ -134,16 +141,49 @@ impl<'a> Parser<'a> { } } + /// Recover if `|` or `||` is the current token and we have one of the + /// tokens `=>`, `if`, `=`, `:`, `;`, `,`, `]`, `)`, or `}` ahead of us. + /// + /// These tokens all indicate that we reached the end of the or-pattern + /// list and can now reliably say that the `|` was an illegal trailing vert. + /// Note that there are more tokens such as `@` for which we know that the `|` + /// is an illegal parse. However, the user's intent is less clear in that case. + fn recover_trailing_vert(&mut self, lo: Option) -> bool { + let is_end_ahead = self.look_ahead(1, |token| match &token.kind { + token::FatArrow // e.g. `a | => 0,`. + | token::Ident(kw::If, false) // e.g. `a | if expr`. + | token::Eq // e.g. `let a | = 0`. + | token::Semi // e.g. `let a |;`. + | token::Colon // e.g. `let a | :`. + | token::Comma // e.g. `let (a |,)`. + | token::CloseDelim(token::Bracket) // e.g. `let [a | ]`. + | token::CloseDelim(token::Paren) // e.g. `let (a | )`. + | token::CloseDelim(token::Brace) => true, // e.g. `let A { f: a | }`. + _ => false, + }); + match (is_end_ahead, &self.token.kind) { + (true, token::BinOp(token::Or)) | (true, token::OrOr) => { + self.ban_illegal_vert(lo, "trailing", "not allowed in an or-pattern"); + self.bump(); + true + } + _ => false, + } + } + /// We have parsed `||` instead of `|`. Error and suggest `|` instead. - fn ban_unexpected_or_or(&mut self) { - self.struct_span_err(self.token.span, "unexpected token `||` after pattern") - .span_suggestion( - self.token.span, - "use a single `|` to separate multiple alternative patterns", - "|".to_owned(), - Applicability::MachineApplicable - ) - .emit(); + fn ban_unexpected_or_or(&mut self, lo: Option) { + let mut err = self.struct_span_err(self.token.span, "unexpected token `||` after pattern"); + err.span_suggestion( + self.token.span, + "use a single `|` to separate multiple alternative patterns", + "|".to_owned(), + Applicability::MachineApplicable + ); + if let Some(lo) = lo { + err.span_label(lo, WHILE_PARSING_OR_MSG); + } + err.emit(); } /// Some special error handling for the "top-level" patterns in a match arm, @@ -198,25 +238,38 @@ impl<'a> Parser<'a> { /// Recursive possibly-or-pattern parser with recovery for an erroneous leading `|`. /// See `parse_pat_with_or` for details on parsing or-patterns. fn parse_pat_with_or_inner(&mut self) -> PResult<'a, P> { - self.recover_leading_vert("only allowed in a top-level pattern"); + self.recover_leading_vert(None, "only allowed in a top-level pattern"); self.parse_pat_with_or(None, GateOr::Yes, RecoverComma::No) } /// Recover if `|` or `||` is here. /// The user is thinking that a leading `|` is allowed in this position. - fn recover_leading_vert(&mut self, ctx: &str) { + fn recover_leading_vert(&mut self, lo: Option, ctx: &str) { if let token::BinOp(token::Or) | token::OrOr = self.token.kind { - let span = self.token.span; - let rm_msg = format!("remove the `{}`", pprust::token_to_string(&self.token)); - - self.struct_span_err(span, &format!("a leading `|` is {}", ctx)) - .span_suggestion(span, &rm_msg, String::new(), Applicability::MachineApplicable) - .emit(); - + self.ban_illegal_vert(lo, "leading", ctx); self.bump(); } } + /// A `|` or possibly `||` token shouldn't be here. Ban it. + fn ban_illegal_vert(&mut self, lo: Option, pos: &str, ctx: &str) { + let span = self.token.span; + let mut err = self.struct_span_err(span, &format!("a {} `|` is {}", pos, ctx)); + err.span_suggestion( + span, + &format!("remove the `{}`", pprust::token_to_string(&self.token)), + String::new(), + Applicability::MachineApplicable, + ); + if let Some(lo) = lo { + err.span_label(lo, WHILE_PARSING_OR_MSG); + } + if let token::OrOr = self.token.kind { + err.note("alternatives in or-patterns are separated with `|`, not `||`"); + } + err.emit(); + } + /// Parses a pattern, with a setting whether modern range patterns (e.g., `a..=b`, `a..b` are /// allowed). fn parse_pat_with_range_pat( @@ -259,7 +312,7 @@ impl<'a> Parser<'a> { self.bump(); self.parse_pat_range_to(RangeEnd::Included(RangeSyntax::DotDotDot), "...")? } - // At this point, token != &, &&, (, [ + // At this point, token != `&`, `&&`, `(`, `[`, `..`, `..=`, or `...`. _ => if self.eat_keyword(kw::Underscore) { // Parse _ PatKind::Wild -- cgit 1.4.1-3-g733a5 From 957986d05620238799ae7053d505f742a0c7d640 Mon Sep 17 00:00:00 2001 From: Vadim Petrochenkov Date: Sun, 18 Aug 2019 01:10:56 +0300 Subject: syntax: Support modern attribute syntax in the `meta` matcher --- src/libsyntax/attr/mod.rs | 16 +++++++++----- src/libsyntax/config.rs | 8 +++---- src/libsyntax/ext/mbe/macro_parser.rs | 2 +- src/libsyntax/mut_visit.rs | 5 ++++- src/libsyntax/parse/attr.rs | 31 +++++++++++++++------------ src/libsyntax/parse/parser/path.rs | 6 +++--- src/libsyntax/parse/token.rs | 2 +- src/libsyntax/print/pprust.rs | 40 +++++++++++++++++++---------------- src/libsyntax_ext/cmdline_attrs.rs | 4 ++-- src/test/ui/cfg/cfg_stmt_expr.rs | 4 ++-- src/test/ui/macros/macro-first-set.rs | 6 ------ 11 files changed, 68 insertions(+), 56 deletions(-) (limited to 'src/libsyntax/parse/parser') diff --git a/src/libsyntax/attr/mod.rs b/src/libsyntax/attr/mod.rs index 009259352ba..7bef693a5be 100644 --- a/src/libsyntax/attr/mod.rs +++ b/src/libsyntax/attr/mod.rs @@ -255,9 +255,8 @@ impl MetaItem { } } -impl Attribute { - /// Extracts the `MetaItem` from inside this `Attribute`. - pub fn meta(&self) -> Option { +impl AttrItem { + crate fn meta(&self, span: Span) -> Option { let mut tokens = self.tokens.trees().peekable(); Some(MetaItem { path: self.path.clone(), @@ -269,9 +268,16 @@ impl Attribute { } else { return None; }, - span: self.span, + span, }) } +} + +impl Attribute { + /// Extracts the MetaItem from inside this Attribute. + pub fn meta(&self) -> Option { + self.item.meta(self.span) + } pub fn parse<'a, T, F>(&self, sess: &'a ParseSess, mut f: F) -> PResult<'a, T> where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>, @@ -524,7 +530,7 @@ impl MetaItem { } Some(TokenTree::Token(Token { kind: token::Interpolated(nt), .. })) => match *nt { token::Nonterminal::NtIdent(ident, _) => Path::from_ident(ident), - token::Nonterminal::NtMeta(ref meta) => return Some(meta.clone()), + token::Nonterminal::NtMeta(ref item) => return item.meta(item.path.span), token::Nonterminal::NtPath(ref path) => path.clone(), _ => return None, }, diff --git a/src/libsyntax/config.rs b/src/libsyntax/config.rs index a9a5c3efd06..2923cc86ba0 100644 --- a/src/libsyntax/config.rs +++ b/src/libsyntax/config.rs @@ -122,8 +122,8 @@ impl<'a> StripUnconfigured<'a> { while !parser.check(&token::CloseDelim(token::Paren)) { let lo = parser.token.span.lo(); - let (path, tokens) = parser.parse_meta_item_unrestricted()?; - expanded_attrs.push((path, tokens, parser.prev_span.with_lo(lo))); + let item = parser.parse_attr_item()?; + expanded_attrs.push((item, parser.prev_span.with_lo(lo))); parser.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Paren)])?; } @@ -150,8 +150,8 @@ impl<'a> StripUnconfigured<'a> { // `cfg_attr` inside of another `cfg_attr`. E.g. // `#[cfg_attr(false, cfg_attr(true, some_attr))]`. expanded_attrs.into_iter() - .flat_map(|(path, tokens, span)| self.process_cfg_attr(ast::Attribute { - item: ast::AttrItem { path, tokens }, + .flat_map(|(item, span)| self.process_cfg_attr(ast::Attribute { + item, id: attr::mk_attr_id(), style: attr.style, is_sugared_doc: false, diff --git a/src/libsyntax/ext/mbe/macro_parser.rs b/src/libsyntax/ext/mbe/macro_parser.rs index 8f49ba9572d..d1c50fd8594 100644 --- a/src/libsyntax/ext/mbe/macro_parser.rs +++ b/src/libsyntax/ext/mbe/macro_parser.rs @@ -924,7 +924,7 @@ fn parse_nt(p: &mut Parser<'_>, sp: Span, name: Symbol) -> Nonterminal { FatalError.raise() } sym::path => token::NtPath(panictry!(p.parse_path(PathStyle::Type))), - sym::meta => token::NtMeta(panictry!(p.parse_meta_item())), + sym::meta => token::NtMeta(panictry!(p.parse_attr_item())), sym::vis => token::NtVis(panictry!(p.parse_visibility(true))), sym::lifetime => if p.check_lifetime() { token::NtLifetime(p.expect_lifetime().ident) diff --git a/src/libsyntax/mut_visit.rs b/src/libsyntax/mut_visit.rs index 4b78282b787..3923b9f297b 100644 --- a/src/libsyntax/mut_visit.rs +++ b/src/libsyntax/mut_visit.rs @@ -682,7 +682,10 @@ pub fn noop_visit_interpolated(nt: &mut token::Nonterminal, vis: token::NtIdent(ident, _is_raw) => vis.visit_ident(ident), token::NtLifetime(ident) => vis.visit_ident(ident), token::NtLiteral(expr) => vis.visit_expr(expr), - token::NtMeta(meta) => vis.visit_meta_item(meta), + token::NtMeta(AttrItem { path, tokens }) => { + vis.visit_path(path); + vis.visit_tts(tokens); + } token::NtPath(path) => vis.visit_path(path), token::NtTT(tt) => vis.visit_tt(tt), token::NtImplItem(item) => diff --git a/src/libsyntax/parse/attr.rs b/src/libsyntax/parse/attr.rs index 707f903916c..f3298b6a65d 100644 --- a/src/libsyntax/parse/attr.rs +++ b/src/libsyntax/parse/attr.rs @@ -90,7 +90,7 @@ impl<'a> Parser<'a> { debug!("parse_attribute_with_inner_parse_policy: inner_parse_policy={:?} self.token={:?}", inner_parse_policy, self.token); - let (span, path, tokens, style) = match self.token.kind { + let (span, item, style) = match self.token.kind { token::Pound => { let lo = self.token.span; self.bump(); @@ -107,7 +107,7 @@ impl<'a> Parser<'a> { }; self.expect(&token::OpenDelim(token::Bracket))?; - let (path, tokens) = self.parse_meta_item_unrestricted()?; + let item = self.parse_attr_item()?; self.expect(&token::CloseDelim(token::Bracket))?; let hi = self.prev_span; @@ -142,7 +142,7 @@ impl<'a> Parser<'a> { } } - (attr_sp, path, tokens, style) + (attr_sp, item, style) } _ => { let token_str = self.this_token_to_string(); @@ -151,7 +151,7 @@ impl<'a> Parser<'a> { }; Ok(ast::Attribute { - item: ast::AttrItem { path, tokens }, + item, id: attr::mk_attr_id(), style, is_sugared_doc: false, @@ -168,17 +168,17 @@ impl<'a> Parser<'a> { /// PATH /// PATH `=` TOKEN_TREE /// The delimiters or `=` are still put into the resulting token stream. - pub fn parse_meta_item_unrestricted(&mut self) -> PResult<'a, (ast::Path, TokenStream)> { - let meta = match self.token.kind { + pub fn parse_attr_item(&mut self) -> PResult<'a, ast::AttrItem> { + let item = match self.token.kind { token::Interpolated(ref nt) => match **nt { - Nonterminal::NtMeta(ref meta) => Some(meta.clone()), + Nonterminal::NtMeta(ref item) => Some(item.clone()), _ => None, }, _ => None, }; - Ok(if let Some(meta) = meta { + Ok(if let Some(item) = item { self.bump(); - (meta.path, meta.kind.tokens(meta.span)) + item } else { let path = self.parse_path(PathStyle::Mod)?; let tokens = if self.check(&token::OpenDelim(DelimToken::Paren)) || @@ -205,7 +205,7 @@ impl<'a> Parser<'a> { } else { TokenStream::empty() }; - (path, tokens) + ast::AttrItem { path, tokens } }) } @@ -273,9 +273,14 @@ impl<'a> Parser<'a> { _ => None, }; - if let Some(meta) = nt_meta { - self.bump(); - return Ok(meta); + if let Some(item) = nt_meta { + return match item.meta(item.path.span) { + Some(meta) => { + self.bump(); + Ok(meta) + } + None => self.unexpected(), + } } let lo = self.token.span; diff --git a/src/libsyntax/parse/parser/path.rs b/src/libsyntax/parse/parser/path.rs index 463ae9124ca..ca823991a2e 100644 --- a/src/libsyntax/parse/parser/path.rs +++ b/src/libsyntax/parse/parser/path.rs @@ -114,9 +114,9 @@ impl<'a> Parser<'a> { pub fn parse_path_allowing_meta(&mut self, style: PathStyle) -> PResult<'a, Path> { let meta_ident = match self.token.kind { token::Interpolated(ref nt) => match **nt { - token::NtMeta(ref meta) => match meta.kind { - ast::MetaItemKind::Word => Some(meta.path.clone()), - _ => None, + token::NtMeta(ref item) => match item.tokens.is_empty() { + true => Some(item.path.clone()), + false => None, }, _ => None, }, diff --git a/src/libsyntax/parse/token.rs b/src/libsyntax/parse/token.rs index fe3b51aa246..fd78a2bd534 100644 --- a/src/libsyntax/parse/token.rs +++ b/src/libsyntax/parse/token.rs @@ -687,7 +687,7 @@ pub enum Nonterminal { NtLifetime(ast::Ident), NtLiteral(P), /// Stuff inside brackets for attributes - NtMeta(ast::MetaItem), + NtMeta(ast::AttrItem), NtPath(ast::Path), NtVis(ast::Visibility), NtTT(TokenTree), diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs index 4b9c2d13f26..7d4ffe493d7 100644 --- a/src/libsyntax/print/pprust.rs +++ b/src/libsyntax/print/pprust.rs @@ -324,7 +324,7 @@ fn token_to_string_ext(token: &Token, convert_dollar_crate: bool) -> String { crate fn nonterminal_to_string(nt: &Nonterminal) -> String { match *nt { token::NtExpr(ref e) => expr_to_string(e), - token::NtMeta(ref e) => meta_item_to_string(e), + token::NtMeta(ref e) => attr_item_to_string(e), token::NtTy(ref e) => ty_to_string(e), token::NtPath(ref e) => path_to_string(e), token::NtItem(ref e) => item_to_string(e), @@ -412,8 +412,8 @@ pub fn meta_list_item_to_string(li: &ast::NestedMetaItem) -> String { to_string(|s| s.print_meta_list_item(li)) } -pub fn meta_item_to_string(mi: &ast::MetaItem) -> String { - to_string(|s| s.print_meta_item(mi)) +fn attr_item_to_string(ai: &ast::AttrItem) -> String { + to_string(|s| s.print_attr_item(ai, ai.path.span)) } pub fn attribute_to_string(attr: &ast::Attribute) -> String { @@ -629,24 +629,28 @@ pub trait PrintState<'a>: std::ops::Deref + std::ops::Dere ast::AttrStyle::Inner => self.word("#!["), ast::AttrStyle::Outer => self.word("#["), } - self.ibox(0); - match attr.tokens.trees().next() { - Some(TokenTree::Delimited(_, delim, tts)) => { - self.print_mac_common( - Some(MacHeader::Path(&attr.path)), false, None, delim, tts, true, attr.span - ); - } - tree => { - self.print_path(&attr.path, false, 0); - if tree.is_some() { - self.space(); - self.print_tts(attr.tokens.clone(), true); - } + self.print_attr_item(&attr.item, attr.span); + self.word("]"); + } + } + + fn print_attr_item(&mut self, item: &ast::AttrItem, span: Span) { + self.ibox(0); + match item.tokens.trees().next() { + Some(TokenTree::Delimited(_, delim, tts)) => { + self.print_mac_common( + Some(MacHeader::Path(&item.path)), false, None, delim, tts, true, span + ); + } + tree => { + self.print_path(&item.path, false, 0); + if tree.is_some() { + self.space(); + self.print_tts(item.tokens.clone(), true); } } - self.end(); - self.word("]"); } + self.end(); } fn print_meta_list_item(&mut self, item: &ast::NestedMetaItem) { diff --git a/src/libsyntax_ext/cmdline_attrs.rs b/src/libsyntax_ext/cmdline_attrs.rs index bb8e3df3db9..203c4a83489 100644 --- a/src/libsyntax_ext/cmdline_attrs.rs +++ b/src/libsyntax_ext/cmdline_attrs.rs @@ -1,6 +1,6 @@ //! Attributes injected into the crate root from command line using `-Z crate-attr`. -use syntax::ast::{self, AttrStyle}; +use syntax::ast::{self, AttrItem, AttrStyle}; use syntax::attr::mk_attr; use syntax::panictry; use syntax::parse::{self, token, ParseSess}; @@ -15,7 +15,7 @@ pub fn inject(mut krate: ast::Crate, parse_sess: &ParseSess, attrs: &[String]) - ); let start_span = parser.token.span; - let (path, tokens) = panictry!(parser.parse_meta_item_unrestricted()); + let AttrItem { path, tokens } = panictry!(parser.parse_attr_item()); let end_span = parser.token.span; if parser.token != token::Eof { parse_sess.span_diagnostic diff --git a/src/test/ui/cfg/cfg_stmt_expr.rs b/src/test/ui/cfg/cfg_stmt_expr.rs index e466ad69f72..6381bb2d588 100644 --- a/src/test/ui/cfg/cfg_stmt_expr.rs +++ b/src/test/ui/cfg/cfg_stmt_expr.rs @@ -57,7 +57,7 @@ fn main() { // check that macro expanded code works macro_rules! if_cfg { - ($cfg:meta $ib:block else $eb:block) => { + ($cfg:meta? $ib:block else $eb:block) => { { let r; #[cfg($cfg)] @@ -69,7 +69,7 @@ fn main() { } } - let n = if_cfg!(unset { + let n = if_cfg!(unset? { 413 } else { 612 diff --git a/src/test/ui/macros/macro-first-set.rs b/src/test/ui/macros/macro-first-set.rs index 34529cdaa64..eb2504d4bfd 100644 --- a/src/test/ui/macros/macro-first-set.rs +++ b/src/test/ui/macros/macro-first-set.rs @@ -252,12 +252,6 @@ test_path!(::std); test_path!(std::u8,); test_path!(any, super, super::super::self::path, X::Z<'a, T=U>); -macro_rules! test_meta_block { - ($($m:meta)* $b:block) => {}; -} - -test_meta_block!(windows {}); - macro_rules! test_lifetime { (1. $($l:lifetime)* $($b:block)*) => {}; (2. $($b:block)* $($l:lifetime)*) => {}; -- cgit 1.4.1-3-g733a5