diff options
Diffstat (limited to 'src/libsyntax/parse/parser.rs')
| -rw-r--r-- | src/libsyntax/parse/parser.rs | 279 |
1 files changed, 125 insertions, 154 deletions
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs index ad9c802ac85..a3ea659940a 100644 --- a/src/libsyntax/parse/parser.rs +++ b/src/libsyntax/parse/parser.rs @@ -71,7 +71,7 @@ bitflags! { } } -type ItemInfo = (Ident, ItemKind, Option<Vec<Attribute> >); +type ItemInfo = (Ident, ItemKind, Option<Vec<Attribute>>); /// How to parse a path. #[derive(Copy, Clone, PartialEq)] @@ -151,10 +151,9 @@ macro_rules! maybe_whole { }; } -fn maybe_append(mut lhs: Vec<Attribute>, rhs: Option<Vec<Attribute>>) - -> Vec<Attribute> { - if let Some(ref attrs) = rhs { - lhs.extend(attrs.iter().cloned()) +fn maybe_append(mut lhs: Vec<Attribute>, mut rhs: Option<Vec<Attribute>>) -> Vec<Attribute> { + if let Some(ref mut rhs) = rhs { + lhs.append(rhs); } lhs } @@ -1347,7 +1346,7 @@ impl<'a> Parser<'a> { Function Style */ - let unsafety = self.parse_unsafety()?; + let unsafety = self.parse_unsafety(); let abi = if self.eat_keyword(keywords::Extern) { self.parse_opt_abi()?.unwrap_or(Abi::C) } else { @@ -1370,11 +1369,12 @@ impl<'a> Parser<'a> { }))) } - pub fn parse_unsafety(&mut self) -> PResult<'a, Unsafety> { + /// Parse unsafety: `unsafe` or nothing. + fn parse_unsafety(&mut self) -> Unsafety { if self.eat_keyword(keywords::Unsafe) { - return Ok(Unsafety::Unsafe); + Unsafety::Unsafe } else { - return Ok(Unsafety::Normal); + Unsafety::Normal } } @@ -4094,28 +4094,6 @@ impl<'a> Parser<'a> { self.look_ahead(2, |t| t.is_keyword(keywords::Trait))) } - fn is_defaultness(&self) -> bool { - // `pub` is included for better error messages - self.token.is_keyword(keywords::Default) && - self.look_ahead(1, |t| t.is_keyword(keywords::Impl) || - t.is_keyword(keywords::Const) || - t.is_keyword(keywords::Fn) || - t.is_keyword(keywords::Unsafe) || - t.is_keyword(keywords::Extern) || - t.is_keyword(keywords::Type) || - t.is_keyword(keywords::Pub)) - } - - fn eat_defaultness(&mut self) -> bool { - let is_defaultness = self.is_defaultness(); - if is_defaultness { - self.bump() - } else { - self.expected_tokens.push(TokenType::Keyword(keywords::Default)); - } - is_defaultness - } - fn eat_macro_def(&mut self, attrs: &[Attribute], vis: &Visibility, lo: Span) -> PResult<'a, Option<P<Item>>> { let token_lo = self.span; @@ -5126,7 +5104,7 @@ impl<'a> Parser<'a> { fn parse_item_fn(&mut self, unsafety: Unsafety, constness: Spanned<Constness>, - abi: abi::Abi) + abi: Abi) -> PResult<'a, ItemInfo> { let (ident, mut generics) = self.parse_fn_header()?; let decl = self.parse_fn_decl(false)?; @@ -5150,13 +5128,10 @@ impl<'a> Parser<'a> { /// - `const unsafe fn` /// - `extern fn` /// - etc - pub fn parse_fn_front_matter(&mut self) - -> PResult<'a, (Spanned<ast::Constness>, - ast::Unsafety, - abi::Abi)> { + pub fn parse_fn_front_matter(&mut self) -> PResult<'a, (Spanned<Constness>, Unsafety, Abi)> { let is_const_fn = self.eat_keyword(keywords::Const); let const_span = self.prev_span; - let unsafety = self.parse_unsafety()?; + let unsafety = self.parse_unsafety(); let (constness, unsafety, abi) = if is_const_fn { (respan(const_span, Constness::Const), unsafety, Abi::Rust) } else { @@ -5191,7 +5166,7 @@ impl<'a> Parser<'a> { mut attrs: Vec<Attribute>) -> PResult<'a, ImplItem> { let lo = self.span; let vis = self.parse_visibility(false)?; - let defaultness = self.parse_defaultness()?; + let defaultness = self.parse_defaultness(); let (name, node, generics) = if self.eat_keyword(keywords::Type) { // This parses the grammar: // ImplItemAssocTy = Ident ["<"...">"] ["where" ...] "=" Ty ";" @@ -5284,7 +5259,7 @@ impl<'a> Parser<'a> { /// Parse a method or a macro invocation in a trait impl. fn parse_impl_method(&mut self, vis: &Visibility, at_end: &mut bool) - -> PResult<'a, (Ident, Vec<ast::Attribute>, ast::Generics, + -> PResult<'a, (Ident, Vec<Attribute>, ast::Generics, ast::ImplItemKind)> { // code copied from parse_macro_use_or_failure... abstraction! if self.token.is_path_start() && !self.is_extern_non_path() { @@ -5373,83 +5348,97 @@ impl<'a> Parser<'a> { } } - /// Parses items implementations variants - /// impl<T> Foo { ... } - /// impl<T> ToString for &'static T { ... } - fn parse_item_impl(&mut self, - unsafety: ast::Unsafety, - defaultness: Defaultness) -> PResult<'a, ItemInfo> { + fn parse_impl_body(&mut self) -> PResult<'a, (Vec<ImplItem>, Vec<Attribute>)> { + self.expect(&token::OpenDelim(token::Brace))?; + let attrs = self.parse_inner_attributes()?; - // First, parse type parameters if necessary. - let mut generics = self.parse_generics()?; + let mut impl_items = Vec::new(); + while !self.eat(&token::CloseDelim(token::Brace)) { + let mut at_end = false; + match self.parse_impl_item(&mut at_end) { + Ok(impl_item) => impl_items.push(impl_item), + Err(mut err) => { + err.emit(); + if !at_end { + self.recover_stmt_(SemiColonMode::Break, BlockMode::Break); + } + } + } + } + Ok((impl_items, attrs)) + } - // Special case: if the next identifier that follows is '(', don't - // allow this to be parsed as a trait. - let could_be_trait = self.token != token::OpenDelim(token::Paren); + /// Parses an implementation item, `impl` keyword is already parsed. + /// impl<'a, T> TYPE { /* impl items */ } + /// impl<'a, T> TRAIT for TYPE { /* impl items */ } + /// impl<'a, T> !TRAIT for TYPE { /* impl items */ } + /// We actually parse slightly more relaxed grammar for better error reporting and recovery. + /// `impl` GENERICS `!`? TYPE `for`? (TYPE | `..`) (`where` PREDICATES)? `{` BODY `}` + /// `impl` GENERICS `!`? TYPE (`where` PREDICATES)? `{` BODY `}` + fn parse_item_impl(&mut self, unsafety: Unsafety, defaultness: Defaultness) + -> PResult<'a, ItemInfo> { + // First, parse generic parameters if necessary. + // FIXME: Disambiguate generic parameters and qualified paths (`impl <A as B>::C {}`). + let mut generics = self.parse_generics()?; - let neg_span = self.span; - let polarity = if self.eat(&token::Not) { + // Disambiguate `impl !Trait for Type { ... }` and `impl ! { ... }` for the never type. + let polarity = if self.check(&token::Not) && self.look_ahead(1, |t| t.can_begin_type()) { + self.bump(); // `!` ast::ImplPolarity::Negative } else { ast::ImplPolarity::Positive }; - // Parse the trait. - let mut ty = self.parse_ty()?; - - // Parse traits, if necessary. - let opt_trait = if could_be_trait && self.eat_keyword(keywords::For) { - // New-style trait. Reinterpret the type as a trait. - match ty.node { - TyKind::Path(None, ref path) => { - Some(TraitRef { - path: (*path).clone(), - ref_id: ty.id, - }) - } - _ => { - self.span_err(ty.span, "not a trait"); - None - } - } + // Parse both types and traits as a type, then reinterpret if necessary. + let ty_first = self.parse_ty()?; + + // If `for` is missing we try to recover. + let has_for = self.eat_keyword(keywords::For); + let missing_for_span = self.prev_span.between(self.span); + + let ty_second = if self.token == token::DotDot { + // We need to report this error after `cfg` expansion for compatibility reasons + self.bump(); // `..`, do not add it to expected tokens + Some(P(Ty { node: TyKind::Err, span: self.prev_span, id: ast::DUMMY_NODE_ID })) + } else if has_for || self.token.can_begin_type() { + Some(self.parse_ty()?) } else { - if polarity == ast::ImplPolarity::Negative { - // This is a negated type implementation - // `impl !MyType {}`, which is not allowed. - self.span_err(neg_span, "inherent implementation can't be negated"); - } None }; - if opt_trait.is_some() { - ty = if self.eat(&token::DotDot) { - P(Ty { node: TyKind::Err, span: self.prev_span, id: ast::DUMMY_NODE_ID }) - } else { - self.parse_ty()? - } - } generics.where_clause = self.parse_where_clause()?; - self.expect(&token::OpenDelim(token::Brace))?; - let attrs = self.parse_inner_attributes()?; + let (impl_items, attrs) = self.parse_impl_body()?; - let mut impl_items = vec![]; - while !self.eat(&token::CloseDelim(token::Brace)) { - let mut at_end = false; - match self.parse_impl_item(&mut at_end) { - Ok(item) => impl_items.push(item), - Err(mut e) => { - e.emit(); - if !at_end { - self.recover_stmt_(SemiColonMode::Break, BlockMode::Break); - } + let item_kind = match ty_second { + Some(ty_second) => { + // impl Trait for Type + if !has_for { + self.span_err(missing_for_span, "missing `for` in a trait impl"); } + + let ty_first = ty_first.into_inner(); + let path = match ty_first.node { + // This notably includes paths passed through `ty` macro fragments (#46438). + TyKind::Path(None, path) => path, + _ => { + self.span_err(ty_first.span, "expected a trait, found type"); + ast::Path::from_ident(ty_first.span, keywords::Invalid.ident()) + } + }; + let trait_ref = TraitRef { path, ref_id: ty_first.id }; + + ItemKind::Impl(unsafety, polarity, defaultness, + generics, Some(trait_ref), ty_second, impl_items) } - } + None => { + // impl Type + ItemKind::Impl(unsafety, polarity, defaultness, + generics, None, ty_first, impl_items) + } + }; - Ok((keywords::Invalid.ident(), - ItemKind::Impl(unsafety, polarity, defaultness, generics, opt_trait, ty, impl_items), - Some(attrs))) + Ok((keywords::Invalid.ident(), item_kind, Some(attrs))) } fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<GenericParam>> { @@ -5722,12 +5711,21 @@ impl<'a> Parser<'a> { Ok(Visibility::Public) } - /// Parse defaultness: DEFAULT or nothing - fn parse_defaultness(&mut self) -> PResult<'a, Defaultness> { - if self.eat_defaultness() { - Ok(Defaultness::Default) + /// Parse defaultness: `default` or nothing. + fn parse_defaultness(&mut self) -> Defaultness { + // `pub` is included for better error messages + if self.check_keyword(keywords::Default) && + self.look_ahead(1, |t| t.is_keyword(keywords::Impl) || + t.is_keyword(keywords::Const) || + t.is_keyword(keywords::Fn) || + t.is_keyword(keywords::Unsafe) || + t.is_keyword(keywords::Extern) || + t.is_keyword(keywords::Type) || + t.is_keyword(keywords::Pub)) { + self.bump(); // `default` + Defaultness::Default } else { - Ok(Defaultness::Final) + Defaultness::Final } } @@ -5797,7 +5795,7 @@ impl<'a> Parser<'a> { let (module, mut attrs) = self.eval_src_mod(path, directory_ownership, id.to_string(), id_span)?; if warn { - let attr = ast::Attribute { + let attr = Attribute { id: attr::mk_attr_id(), style: ast::AttrStyle::Outer, path: ast::Path::from_ident(syntax_pos::DUMMY_SP, @@ -5837,7 +5835,7 @@ impl<'a> Parser<'a> { } } - pub fn submod_path_from_attr(attrs: &[ast::Attribute], dir_path: &Path) -> Option<PathBuf> { + pub fn submod_path_from_attr(attrs: &[Attribute], dir_path: &Path) -> Option<PathBuf> { attr::first_attr_value_str_by_name(attrs, "path").map(|d| dir_path.join(&d.as_str())) } @@ -5906,7 +5904,7 @@ impl<'a> Parser<'a> { fn submod_path(&mut self, id: ast::Ident, - outer_attrs: &[ast::Attribute], + outer_attrs: &[Attribute], id_sp: Span) -> PResult<'a, ModulePathSuccess> { if let Some(path) = Parser::submod_path_from_attr(outer_attrs, &self.directory.path) { @@ -5999,7 +5997,7 @@ impl<'a> Parser<'a> { directory_ownership: DirectoryOwnership, name: String, id_sp: Span) - -> PResult<'a, (ast::ItemKind, Vec<ast::Attribute> )> { + -> PResult<'a, (ast::ItemKind, Vec<Attribute> )> { let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut(); if let Some(i) = included_mod_stack.iter().position(|p| *p == path) { let mut err = String::from("circular modules: "); @@ -6122,7 +6120,7 @@ impl<'a> Parser<'a> { /// extern {} fn parse_item_foreign_mod(&mut self, lo: Span, - opt_abi: Option<abi::Abi>, + opt_abi: Option<Abi>, visibility: Visibility, mut attrs: Vec<Attribute>) -> PResult<'a, P<Item>> { @@ -6225,7 +6223,7 @@ impl<'a> Parser<'a> { /// Parses a string as an ABI spec on an extern type or module. Consumes /// the `extern` keyword, if one is found. - fn parse_opt_abi(&mut self) -> PResult<'a, Option<abi::Abi>> { + fn parse_opt_abi(&mut self) -> PResult<'a, Option<Abi>> { match self.token { token::Literal(token::Str_(s), suf) | token::Literal(token::StrRaw(s, _), suf) => { let sp = self.span; @@ -6330,11 +6328,7 @@ impl<'a> Parser<'a> { || (self.check_keyword(keywords::Unsafe) && self.look_ahead(1, |t| t.is_keyword(keywords::Fn))) { // CONST FUNCTION ITEM - let unsafety = if self.eat_keyword(keywords::Unsafe) { - Unsafety::Unsafe - } else { - Unsafety::Normal - }; + let unsafety = self.parse_unsafety(); self.bump(); let (ident, item_, extra_attrs) = self.parse_item_fn(unsafety, @@ -6370,7 +6364,7 @@ impl<'a> Parser<'a> { self.look_ahead(1, |t| t.is_keyword(keywords::Auto))) { // UNSAFE TRAIT ITEM - self.expect_keyword(keywords::Unsafe)?; + self.bump(); // `unsafe` let is_auto = if self.eat_keyword(keywords::Trait) { IsAuto::No } else { @@ -6379,7 +6373,7 @@ impl<'a> Parser<'a> { IsAuto::Yes }; let (ident, item_, extra_attrs) = - self.parse_item_trait(is_auto, ast::Unsafety::Unsafe)?; + self.parse_item_trait(is_auto, Unsafety::Unsafe)?; let prev_span = self.prev_span; let item = self.mk_item(lo.to(prev_span), ident, @@ -6388,26 +6382,21 @@ impl<'a> Parser<'a> { maybe_append(attrs, extra_attrs)); return Ok(Some(item)); } - if (self.check_keyword(keywords::Unsafe) && - self.look_ahead(1, |t| t.is_keyword(keywords::Impl))) || - (self.check_keyword(keywords::Default) && - self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe)) && - self.look_ahead(2, |t| t.is_keyword(keywords::Impl))) - { + if self.check_keyword(keywords::Impl) || + self.check_keyword(keywords::Unsafe) && + self.look_ahead(1, |t| t.is_keyword(keywords::Impl)) || + self.check_keyword(keywords::Default) && + self.look_ahead(1, |t| t.is_keyword(keywords::Impl)) || + self.check_keyword(keywords::Default) && + self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe)) { // IMPL ITEM - let defaultness = self.parse_defaultness()?; - self.expect_keyword(keywords::Unsafe)?; + let defaultness = self.parse_defaultness(); + let unsafety = self.parse_unsafety(); self.expect_keyword(keywords::Impl)?; - let (ident, - item_, - extra_attrs) = self.parse_item_impl(ast::Unsafety::Unsafe, defaultness)?; - let prev_span = self.prev_span; - let item = self.mk_item(lo.to(prev_span), - ident, - item_, - visibility, - maybe_append(attrs, extra_attrs)); - return Ok(Some(item)); + let (ident, item, extra_attrs) = self.parse_item_impl(unsafety, defaultness)?; + let span = lo.to(self.prev_span); + return Ok(Some(self.mk_item(span, ident, item, visibility, + maybe_append(attrs, extra_attrs)))); } if self.check_keyword(keywords::Fn) { // FUNCTION ITEM @@ -6428,7 +6417,7 @@ impl<'a> Parser<'a> { if self.check_keyword(keywords::Unsafe) && self.look_ahead(1, |t| *t != token::OpenDelim(token::Brace)) { // UNSAFE FUNCTION ITEM - self.bump(); + self.bump(); // `unsafe` let abi = if self.eat_keyword(keywords::Extern) { self.parse_opt_abi()?.unwrap_or(Abi::C) } else { @@ -6495,25 +6484,7 @@ impl<'a> Parser<'a> { }; // TRAIT ITEM let (ident, item_, extra_attrs) = - self.parse_item_trait(is_auto, ast::Unsafety::Normal)?; - let prev_span = self.prev_span; - let item = self.mk_item(lo.to(prev_span), - ident, - item_, - visibility, - maybe_append(attrs, extra_attrs)); - return Ok(Some(item)); - } - if (self.check_keyword(keywords::Impl)) || - (self.check_keyword(keywords::Default) && - self.look_ahead(1, |t| t.is_keyword(keywords::Impl))) - { - // IMPL ITEM - let defaultness = self.parse_defaultness()?; - self.expect_keyword(keywords::Impl)?; - let (ident, - item_, - extra_attrs) = self.parse_item_impl(ast::Unsafety::Normal, defaultness)?; + self.parse_item_trait(is_auto, Unsafety::Normal)?; let prev_span = self.prev_span; let item = self.mk_item(lo.to(prev_span), ident, |