diff options
Diffstat (limited to 'src/libsyntax/parse/parser/item.rs')
| -rw-r--r-- | src/libsyntax/parse/parser/item.rs | 700 |
1 files changed, 493 insertions, 207 deletions
diff --git a/src/libsyntax/parse/parser/item.rs b/src/libsyntax/parse/parser/item.rs index 3c60c88e2aa..73bd80e2a21 100644 --- a/src/libsyntax/parse/parser/item.rs +++ b/src/libsyntax/parse/parser/item.rs @@ -1,34 +1,28 @@ -use super::{Parser, PResult, PathStyle, SemiColonMode, BlockMode, ParamCfg}; +use super::{Parser, PResult, PathStyle, SemiColonMode, BlockMode}; +use super::diagnostics::{Error, dummy_arg}; use crate::maybe_whole; use crate::ptr::P; -use crate::ast::{ - self, DUMMY_NODE_ID, Ident, Attribute, AttrStyle, - Item, ItemKind, ImplItem, ImplItemKind, TraitItem, TraitItemKind, - UseTree, UseTreeKind, PathSegment, - IsAuto, Constness, IsAsync, Unsafety, Defaultness, - Visibility, VisibilityKind, Mutability, FnDecl, FnHeader, MethodSig, Block, - ForeignItem, ForeignItemKind, - Ty, TyKind, Generics, GenericBounds, TraitRef, - EnumDef, VariantData, StructField, AnonConst, - Mac, MacDelimiter, -}; -use crate::ext::base::DummyResult; +use crate::ast::{self, DUMMY_NODE_ID, Ident, Attribute, AttrStyle, AnonConst, Item, ItemKind}; +use crate::ast::{ImplItem, ImplItemKind, TraitItem, TraitItemKind, UseTree, UseTreeKind}; +use crate::ast::{PathSegment, IsAuto, Constness, IsAsync, Unsafety, Defaultness}; +use crate::ast::{Visibility, VisibilityKind, Mutability, FnHeader, ForeignItem, ForeignItemKind}; +use crate::ast::{Ty, TyKind, Generics, GenericBounds, TraitRef, EnumDef, VariantData, StructField}; +use crate::ast::{Mac, MacDelimiter, Block, BindingMode, FnDecl, MethodSig, SelfKind, Param}; use crate::parse::token; -use crate::parse::parser::maybe_append; -use crate::parse::diagnostics::Error; use crate::tokenstream::{TokenTree, TokenStream}; -use crate::source_map::{respan, Span}; use crate::symbol::{kw, sym}; +use crate::source_map::{self, respan, Span}; +use crate::ThinVec; -use std::mem; use log::debug; +use std::mem; use rustc_target::spec::abi::Abi; use errors::{Applicability, DiagnosticBuilder, DiagnosticId, StashKey}; /// Whether the type alias or associated type is a concrete type or an opaque type. #[derive(Debug)] -pub enum AliasKind { +pub(super) enum AliasKind { /// Just a new name for the same type. Weak(P<Ty>), /// Only trait impls of the type will be usable, not the actual type itself. @@ -412,7 +406,7 @@ impl<'a> Parser<'a> { self.parse_macro_use_or_failure(attrs, macros_allowed, attributes_allowed, lo, vis) } - fn mk_item_with_info( + pub(super) fn mk_item_with_info( &self, attrs: Vec<Attribute>, lo: Span, @@ -421,18 +415,15 @@ impl<'a> Parser<'a> { ) -> PResult<'a, Option<P<Item>>> { let (ident, item, extra_attrs) = info; let span = lo.to(self.prev_span); - let attrs = maybe_append(attrs, extra_attrs); + let attrs = Self::maybe_append(attrs, extra_attrs); Ok(Some(self.mk_item(span, ident, item, vis, attrs))) } - fn recover_first_param(&mut self) -> &'static str { - match self.parse_outer_attributes() - .and_then(|_| self.parse_self_param()) - .map_err(|mut e| e.cancel()) - { - Ok(Some(_)) => "method", - _ => "function", + fn maybe_append<T>(mut lhs: Vec<T>, mut rhs: Option<Vec<T>>) -> Vec<T> { + if let Some(ref mut rhs) = rhs { + lhs.append(rhs); } + lhs } /// This is the fall-through for parsing items. @@ -620,7 +611,7 @@ impl<'a> Parser<'a> { 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(DummyResult::raw_ty(self.prev_span, true)) + Some(self.mk_ty(self.prev_span, TyKind::Err)) } else if has_for || self.token.can_begin_type() { Some(self.parse_ty()?) } else { @@ -707,9 +698,11 @@ impl<'a> Parser<'a> { Ok(item) } - fn parse_impl_item_(&mut self, - at_end: &mut bool, - mut attrs: Vec<Attribute>) -> PResult<'a, ImplItem> { + fn parse_impl_item_( + &mut self, + at_end: &mut bool, + mut attrs: Vec<Attribute>, + ) -> PResult<'a, ImplItem> { let lo = self.token.span; let vis = self.parse_visibility(false)?; let defaultness = self.parse_defaultness(); @@ -722,8 +715,11 @@ impl<'a> Parser<'a> { (name, kind, generics) } else if self.is_const_item() { self.parse_impl_const()? + } else if let Some(mac) = self.parse_assoc_macro_invoc("impl", Some(&vis), at_end)? { + // FIXME: code copied from `parse_macro_use_or_failure` -- use abstraction! + (Ident::invalid(), ast::ImplItemKind::Macro(mac), Generics::default()) } else { - let (name, inner_attrs, generics, kind) = self.parse_impl_method(&vis, at_end)?; + let (name, inner_attrs, generics, kind) = self.parse_impl_method(at_end)?; attrs.extend(inner_attrs); (name, kind, generics) }; @@ -783,71 +779,6 @@ impl<'a> Parser<'a> { Ok((name, ImplItemKind::Const(typ, expr), Generics::default())) } - /// Parses 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<Attribute>, Generics, ImplItemKind)> { - // FIXME: code copied from `parse_macro_use_or_failure` -- use abstraction! - if let Some(mac) = self.parse_assoc_macro_invoc("impl", Some(vis), at_end)? { - // method macro - Ok((Ident::invalid(), vec![], Generics::default(), ast::ImplItemKind::Macro(mac))) - } else { - let (ident, sig, generics) = self.parse_method_sig(|_| true)?; - *at_end = true; - let (inner_attrs, body) = self.parse_inner_attrs_and_block()?; - Ok((ident, inner_attrs, generics, ast::ImplItemKind::Method(sig, body))) - } - } - - /// Parse the "signature", including the identifier, parameters, and generics - /// of a method. The body is not parsed as that differs between `trait`s and `impl`s. - fn parse_method_sig( - &mut self, - is_name_required: fn(&token::Token) -> bool, - ) -> PResult<'a, (Ident, MethodSig, Generics)> { - let header = self.parse_fn_front_matter()?; - let (ident, decl, generics) = self.parse_fn_sig(ParamCfg { - is_self_allowed: true, - allow_c_variadic: false, - is_name_required, - })?; - Ok((ident, MethodSig { header, decl }, generics)) - } - - /// Parses all the "front matter" for a `fn` declaration, up to - /// and including the `fn` keyword: - /// - /// - `const fn` - /// - `unsafe fn` - /// - `const unsafe fn` - /// - `extern fn` - /// - etc. - fn parse_fn_front_matter(&mut self) -> PResult<'a, FnHeader> { - let is_const_fn = self.eat_keyword(kw::Const); - let const_span = self.prev_span; - let asyncness = self.parse_asyncness(); - if let IsAsync::Async { .. } = asyncness { - self.ban_async_in_2015(self.prev_span); - } - let asyncness = respan(self.prev_span, asyncness); - let unsafety = self.parse_unsafety(); - let (constness, unsafety, abi) = if is_const_fn { - (respan(const_span, Constness::Const), unsafety, Abi::Rust) - } else { - let abi = self.parse_extern_abi()?; - (respan(self.prev_span, Constness::NotConst), unsafety, abi) - }; - if !self.eat_keyword(kw::Fn) { - // It is possible for `expect_one_of` to recover given the contents of - // `self.expected_tokens`, therefore, do not use `self.unexpected()` which doesn't - // account for this. - if !self.expect_one_of(&[], &[])? { unreachable!() } - } - Ok(FnHeader { constness, unsafety, asyncness, abi }) - } - /// Parses `auto? trait Foo { ... }` or `trait Foo = Bar;`. fn parse_item_trait(&mut self, unsafety: Unsafety) -> PResult<'a, ItemInfo> { // Parse optional `auto` prefix. @@ -957,13 +888,7 @@ impl<'a> Parser<'a> { // trait item macro. (Ident::invalid(), TraitItemKind::Macro(mac), Generics::default()) } else { - // This is somewhat dubious; We don't want to allow - // argument names to be left off if there is a definition... - // - // We don't allow argument names to be left off in edition 2018. - let (ident, sig, generics) = self.parse_method_sig(|t| t.span.rust_2018())?; - let body = self.parse_trait_method_body(at_end, &mut attrs)?; - (ident, TraitItemKind::Method(sig, body), generics) + self.parse_trait_item_method(at_end, &mut attrs)? }; Ok(TraitItem { @@ -991,43 +916,6 @@ impl<'a> Parser<'a> { Ok((ident, TraitItemKind::Const(ty, default), Generics::default())) } - /// Parse the "body" of a method in a trait item definition. - /// This can either be `;` when there's no body, - /// or e.g. a block when the method is a provided one. - fn parse_trait_method_body( - &mut self, - at_end: &mut bool, - attrs: &mut Vec<Attribute>, - ) -> PResult<'a, Option<P<Block>>> { - Ok(match self.token.kind { - token::Semi => { - debug!("parse_trait_method_body(): parsing required method"); - self.bump(); - *at_end = true; - None - } - token::OpenDelim(token::Brace) => { - debug!("parse_trait_method_body(): parsing provided method"); - *at_end = true; - let (inner_attrs, body) = self.parse_inner_attrs_and_block()?; - attrs.extend(inner_attrs.iter().cloned()); - Some(body) - } - token::Interpolated(ref nt) => { - match **nt { - token::NtBlock(..) => { - *at_end = true; - let (inner_attrs, body) = self.parse_inner_attrs_and_block()?; - attrs.extend(inner_attrs.iter().cloned()); - Some(body) - } - _ => return self.expected_semi_or_open_brace(), - } - } - _ => return self.expected_semi_or_open_brace(), - }) - } - /// Parses the following grammar: /// /// TraitItemAssocTy = Ident ["<"...">"] [":" [GenericBounds]] ["where" ...] ["=" Ty] @@ -1194,45 +1082,6 @@ impl<'a> Parser<'a> { Ok(ident) } - /// Parses an item-position function declaration. - fn parse_item_fn( - &mut self, - lo: Span, - vis: Visibility, - attrs: Vec<Attribute>, - header: FnHeader, - ) -> PResult<'a, Option<P<Item>>> { - let (ident, decl, generics) = self.parse_fn_sig(ParamCfg { - is_self_allowed: false, - allow_c_variadic: header.abi == Abi::C && header.unsafety == Unsafety::Unsafe, - is_name_required: |_| true, - })?; - let (inner_attrs, body) = self.parse_inner_attrs_and_block()?; - let kind = ItemKind::Fn(decl, header, generics, body); - self.mk_item_with_info(attrs, lo, vis, (ident, kind, Some(inner_attrs))) - } - - /// Parse the "signature", including the identifier, parameters, and generics of a function. - fn parse_fn_sig(&mut self, cfg: ParamCfg) -> PResult<'a, (Ident, P<FnDecl>, Generics)> { - let ident = self.parse_ident()?; - let mut generics = self.parse_generics()?; - let decl = self.parse_fn_decl(cfg, true)?; - generics.where_clause = self.parse_where_clause()?; - Ok((ident, decl, generics)) - } - - /// Parses the parameter list and result type of a function declaration. - pub(super) fn parse_fn_decl( - &mut self, - cfg: ParamCfg, - ret_allow_plus: bool, - ) -> PResult<'a, P<FnDecl>> { - Ok(P(FnDecl { - inputs: self.parse_fn_params(cfg)?, - output: self.parse_ret_ty(ret_allow_plus)?, - })) - } - /// Parses `extern` for foreign ABIs modules. /// /// `extern` is expected to have been @@ -1273,7 +1122,7 @@ impl<'a> Parser<'a> { } /// Parses a foreign item. - crate fn parse_foreign_item(&mut self, extern_sp: Span) -> PResult<'a, ForeignItem> { + pub fn parse_foreign_item(&mut self, extern_sp: Span) -> PResult<'a, ForeignItem> { maybe_whole!(self, NtForeignItem, |ni| ni); let attrs = self.parse_outer_attributes()?; @@ -1344,32 +1193,6 @@ impl<'a> Parser<'a> { } } - /// Parses a function declaration from a foreign module. - fn parse_item_foreign_fn( - &mut self, - vis: ast::Visibility, - lo: Span, - attrs: Vec<Attribute>, - extern_sp: Span, - ) -> PResult<'a, ForeignItem> { - self.expect_keyword(kw::Fn)?; - let (ident, decl, generics) = self.parse_fn_sig(super::ParamCfg { - is_self_allowed: false, - allow_c_variadic: true, - is_name_required: |_| true, - })?; - let span = lo.to(self.token.span); - self.parse_semi_or_incorrect_foreign_fn_body(&ident, extern_sp)?; - Ok(ast::ForeignItem { - ident, - attrs, - kind: ForeignItemKind::Fn(decl, generics), - id: DUMMY_NODE_ID, - span, - vis, - }) - } - /// Parses a static item from a foreign module. /// Assumes that the `static` keyword is already parsed. fn parse_item_foreign_static(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>) @@ -1910,3 +1733,466 @@ impl<'a> Parser<'a> { }) } } + +/// The parsing configuration used to parse a parameter list (see `parse_fn_params`). +pub(super) struct ParamCfg { + /// Is `self` is allowed as the first parameter? + pub is_self_allowed: bool, + /// Is `...` allowed as the tail of the parameter list? + pub allow_c_variadic: bool, + /// `is_name_required` decides if, per-parameter, + /// the parameter must have a pattern or just a type. + pub is_name_required: fn(&token::Token) -> bool, +} + +/// Parsing of functions and methods. +impl<'a> Parser<'a> { + /// Parses an item-position function declaration. + fn parse_item_fn( + &mut self, + lo: Span, + vis: Visibility, + attrs: Vec<Attribute>, + header: FnHeader, + ) -> PResult<'a, Option<P<Item>>> { + let (ident, decl, generics) = self.parse_fn_sig(ParamCfg { + is_self_allowed: false, + allow_c_variadic: header.abi == Abi::C && header.unsafety == Unsafety::Unsafe, + is_name_required: |_| true, + })?; + let (inner_attrs, body) = self.parse_inner_attrs_and_block()?; + let kind = ItemKind::Fn(decl, header, generics, body); + self.mk_item_with_info(attrs, lo, vis, (ident, kind, Some(inner_attrs))) + } + + /// Parses a function declaration from a foreign module. + fn parse_item_foreign_fn( + &mut self, + vis: ast::Visibility, + lo: Span, + attrs: Vec<Attribute>, + extern_sp: Span, + ) -> PResult<'a, ForeignItem> { + self.expect_keyword(kw::Fn)?; + let (ident, decl, generics) = self.parse_fn_sig(ParamCfg { + is_self_allowed: false, + allow_c_variadic: true, + is_name_required: |_| true, + })?; + let span = lo.to(self.token.span); + self.parse_semi_or_incorrect_foreign_fn_body(&ident, extern_sp)?; + Ok(ast::ForeignItem { + ident, + attrs, + kind: ForeignItemKind::Fn(decl, generics), + id: DUMMY_NODE_ID, + span, + vis, + }) + } + + /// Parses a method or a macro invocation in a trait impl. + fn parse_impl_method( + &mut self, + at_end: &mut bool, + ) -> PResult<'a, (Ident, Vec<Attribute>, Generics, ImplItemKind)> { + let (ident, sig, generics) = self.parse_method_sig(|_| true)?; + *at_end = true; + let (inner_attrs, body) = self.parse_inner_attrs_and_block()?; + Ok((ident, inner_attrs, generics, ast::ImplItemKind::Method(sig, body))) + } + + fn parse_trait_item_method( + &mut self, + at_end: &mut bool, + attrs: &mut Vec<Attribute>, + ) -> PResult<'a, (Ident, TraitItemKind, Generics)> { + // This is somewhat dubious; We don't want to allow + // argument names to be left off if there is a definition... + // + // We don't allow argument names to be left off in edition 2018. + let (ident, sig, generics) = self.parse_method_sig(|t| t.span.rust_2018())?; + let body = self.parse_trait_method_body(at_end, attrs)?; + Ok((ident, TraitItemKind::Method(sig, body), generics)) + } + + /// Parse the "body" of a method in a trait item definition. + /// This can either be `;` when there's no body, + /// or e.g. a block when the method is a provided one. + fn parse_trait_method_body( + &mut self, + at_end: &mut bool, + attrs: &mut Vec<Attribute>, + ) -> PResult<'a, Option<P<Block>>> { + Ok(match self.token.kind { + token::Semi => { + debug!("parse_trait_method_body(): parsing required method"); + self.bump(); + *at_end = true; + None + } + token::OpenDelim(token::Brace) => { + debug!("parse_trait_method_body(): parsing provided method"); + *at_end = true; + let (inner_attrs, body) = self.parse_inner_attrs_and_block()?; + attrs.extend(inner_attrs.iter().cloned()); + Some(body) + } + token::Interpolated(ref nt) => { + match **nt { + token::NtBlock(..) => { + *at_end = true; + let (inner_attrs, body) = self.parse_inner_attrs_and_block()?; + attrs.extend(inner_attrs.iter().cloned()); + Some(body) + } + _ => return self.expected_semi_or_open_brace(), + } + } + _ => return self.expected_semi_or_open_brace(), + }) + } + + /// Parse the "signature", including the identifier, parameters, and generics + /// of a method. The body is not parsed as that differs between `trait`s and `impl`s. + fn parse_method_sig( + &mut self, + is_name_required: fn(&token::Token) -> bool, + ) -> PResult<'a, (Ident, MethodSig, Generics)> { + let header = self.parse_fn_front_matter()?; + let (ident, decl, generics) = self.parse_fn_sig(ParamCfg { + is_self_allowed: true, + allow_c_variadic: false, + is_name_required, + })?; + Ok((ident, MethodSig { header, decl }, generics)) + } + + /// Parses all the "front matter" for a `fn` declaration, up to + /// and including the `fn` keyword: + /// + /// - `const fn` + /// - `unsafe fn` + /// - `const unsafe fn` + /// - `extern fn` + /// - etc. + fn parse_fn_front_matter(&mut self) -> PResult<'a, FnHeader> { + let is_const_fn = self.eat_keyword(kw::Const); + let const_span = self.prev_span; + let asyncness = self.parse_asyncness(); + if let IsAsync::Async { .. } = asyncness { + self.ban_async_in_2015(self.prev_span); + } + let asyncness = respan(self.prev_span, asyncness); + let unsafety = self.parse_unsafety(); + let (constness, unsafety, abi) = if is_const_fn { + (respan(const_span, Constness::Const), unsafety, Abi::Rust) + } else { + let abi = self.parse_extern_abi()?; + (respan(self.prev_span, Constness::NotConst), unsafety, abi) + }; + if !self.eat_keyword(kw::Fn) { + // It is possible for `expect_one_of` to recover given the contents of + // `self.expected_tokens`, therefore, do not use `self.unexpected()` which doesn't + // account for this. + if !self.expect_one_of(&[], &[])? { unreachable!() } + } + Ok(FnHeader { constness, unsafety, asyncness, abi }) + } + + /// Parse the "signature", including the identifier, parameters, and generics of a function. + fn parse_fn_sig(&mut self, cfg: ParamCfg) -> PResult<'a, (Ident, P<FnDecl>, Generics)> { + let ident = self.parse_ident()?; + let mut generics = self.parse_generics()?; + let decl = self.parse_fn_decl(cfg, true)?; + generics.where_clause = self.parse_where_clause()?; + Ok((ident, decl, generics)) + } + + /// Parses the parameter list and result type of a function declaration. + pub(super) fn parse_fn_decl( + &mut self, + cfg: ParamCfg, + ret_allow_plus: bool, + ) -> PResult<'a, P<FnDecl>> { + Ok(P(FnDecl { + inputs: self.parse_fn_params(cfg)?, + output: self.parse_ret_ty(ret_allow_plus)?, + })) + } + + /// Parses the parameter list of a function, including the `(` and `)` delimiters. + fn parse_fn_params(&mut self, mut cfg: ParamCfg) -> PResult<'a, Vec<Param>> { + let sp = self.token.span; + let is_trait_item = cfg.is_self_allowed; + let mut c_variadic = false; + // Parse the arguments, starting out with `self` being possibly allowed... + let (params, _) = self.parse_paren_comma_seq(|p| { + let param = p.parse_param_general(&cfg, is_trait_item); + // ...now that we've parsed the first argument, `self` is no longer allowed. + cfg.is_self_allowed = false; + + match param { + Ok(param) => Ok( + if let TyKind::CVarArgs = param.ty.kind { + c_variadic = true; + if p.token != token::CloseDelim(token::Paren) { + p.span_err( + p.token.span, + "`...` must be the last argument of a C-variadic function", + ); + // FIXME(eddyb) this should probably still push `CVarArgs`. + // Maybe AST validation/HIR lowering should emit the above error? + None + } else { + Some(param) + } + } else { + Some(param) + } + ), + Err(mut e) => { + e.emit(); + let lo = p.prev_span; + // Skip every token until next possible arg or end. + p.eat_to_tokens(&[&token::Comma, &token::CloseDelim(token::Paren)]); + // Create a placeholder argument for proper arg count (issue #34264). + let span = lo.to(p.prev_span); + Ok(Some(dummy_arg(Ident::new(kw::Invalid, span)))) + } + } + })?; + + let mut params: Vec<_> = params.into_iter().filter_map(|x| x).collect(); + + // Replace duplicated recovered params with `_` pattern to avoid unecessary errors. + self.deduplicate_recovered_params_names(&mut params); + + if c_variadic && params.len() <= 1 { + self.span_err( + sp, + "C-variadic function must be declared with at least one named argument", + ); + } + + Ok(params) + } + + /// Skips unexpected attributes and doc comments in this position and emits an appropriate + /// error. + /// This version of parse param doesn't necessarily require identifier names. + fn parse_param_general(&mut self, cfg: &ParamCfg, is_trait_item: bool) -> PResult<'a, Param> { + let lo = self.token.span; + let attrs = self.parse_outer_attributes()?; + + // Possibly parse `self`. Recover if we parsed it and it wasn't allowed here. + if let Some(mut param) = self.parse_self_param()? { + param.attrs = attrs.into(); + return if cfg.is_self_allowed { + Ok(param) + } else { + self.recover_bad_self_param(param, is_trait_item) + }; + } + + let is_name_required = match self.token.kind { + token::DotDotDot => false, + _ => (cfg.is_name_required)(&self.token), + }; + let (pat, ty) = if is_name_required || self.is_named_param() { + debug!("parse_param_general parse_pat (is_name_required:{})", is_name_required); + + let pat = self.parse_fn_param_pat()?; + if let Err(mut err) = self.expect(&token::Colon) { + return if let Some(ident) = self.parameter_without_type( + &mut err, + pat, + is_name_required, + cfg.is_self_allowed, + is_trait_item, + ) { + err.emit(); + Ok(dummy_arg(ident)) + } else { + Err(err) + }; + } + + self.eat_incorrect_doc_comment_for_param_type(); + (pat, self.parse_ty_common(true, true, cfg.allow_c_variadic)?) + } else { + debug!("parse_param_general ident_to_pat"); + let parser_snapshot_before_ty = self.clone(); + self.eat_incorrect_doc_comment_for_param_type(); + let mut ty = self.parse_ty_common(true, true, cfg.allow_c_variadic); + if ty.is_ok() && self.token != token::Comma && + self.token != token::CloseDelim(token::Paren) { + // This wasn't actually a type, but a pattern looking like a type, + // so we are going to rollback and re-parse for recovery. + ty = self.unexpected(); + } + match ty { + Ok(ty) => { + let ident = Ident::new(kw::Invalid, self.prev_span); + let bm = BindingMode::ByValue(Mutability::Immutable); + let pat = self.mk_pat_ident(ty.span, bm, ident); + (pat, ty) + } + // If this is a C-variadic argument and we hit an error, return the error. + Err(err) if self.token == token::DotDotDot => return Err(err), + // Recover from attempting to parse the argument as a type without pattern. + Err(mut err) => { + err.cancel(); + mem::replace(self, parser_snapshot_before_ty); + self.recover_arg_parse()? + } + } + }; + + let span = lo.to(self.token.span); + + Ok(Param { + attrs: attrs.into(), + id: ast::DUMMY_NODE_ID, + is_placeholder: false, + pat, + span, + ty, + }) + } + + /// Returns the parsed optional self parameter and whether a self shortcut was used. + /// + /// See `parse_self_param_with_attrs` to collect attributes. + fn parse_self_param(&mut self) -> PResult<'a, Option<Param>> { + // Extract an identifier *after* having confirmed that the token is one. + let expect_self_ident = |this: &mut Self| { + match this.token.kind { + // Preserve hygienic context. + token::Ident(name, _) => { + let span = this.token.span; + this.bump(); + Ident::new(name, span) + } + _ => unreachable!(), + } + }; + // Is `self` `n` tokens ahead? + let is_isolated_self = |this: &Self, n| { + this.is_keyword_ahead(n, &[kw::SelfLower]) + && this.look_ahead(n + 1, |t| t != &token::ModSep) + }; + // Is `mut self` `n` tokens ahead? + let is_isolated_mut_self = |this: &Self, n| { + this.is_keyword_ahead(n, &[kw::Mut]) + && is_isolated_self(this, n + 1) + }; + // Parse `self` or `self: TYPE`. We already know the current token is `self`. + let parse_self_possibly_typed = |this: &mut Self, m| { + let eself_ident = expect_self_ident(this); + let eself_hi = this.prev_span; + let eself = if this.eat(&token::Colon) { + SelfKind::Explicit(this.parse_ty()?, m) + } else { + SelfKind::Value(m) + }; + Ok((eself, eself_ident, eself_hi)) + }; + // Recover for the grammar `*self`, `*const self`, and `*mut self`. + let recover_self_ptr = |this: &mut Self| { + let msg = "cannot pass `self` by raw pointer"; + let span = this.token.span; + this.struct_span_err(span, msg) + .span_label(span, msg) + .emit(); + + Ok((SelfKind::Value(Mutability::Immutable), expect_self_ident(this), this.prev_span)) + }; + + // Parse optional `self` parameter of a method. + // Only a limited set of initial token sequences is considered `self` parameters; anything + // else is parsed as a normal function parameter list, so some lookahead is required. + let eself_lo = self.token.span; + let (eself, eself_ident, eself_hi) = match self.token.kind { + token::BinOp(token::And) => { + let eself = if is_isolated_self(self, 1) { + // `&self` + self.bump(); + SelfKind::Region(None, Mutability::Immutable) + } else if is_isolated_mut_self(self, 1) { + // `&mut self` + self.bump(); + self.bump(); + SelfKind::Region(None, Mutability::Mutable) + } else if self.look_ahead(1, |t| t.is_lifetime()) && is_isolated_self(self, 2) { + // `&'lt self` + self.bump(); + let lt = self.expect_lifetime(); + SelfKind::Region(Some(lt), Mutability::Immutable) + } else if self.look_ahead(1, |t| t.is_lifetime()) && is_isolated_mut_self(self, 2) { + // `&'lt mut self` + self.bump(); + let lt = self.expect_lifetime(); + self.bump(); + SelfKind::Region(Some(lt), Mutability::Mutable) + } else { + // `¬_self` + return Ok(None); + }; + (eself, expect_self_ident(self), self.prev_span) + } + // `*self` + token::BinOp(token::Star) if is_isolated_self(self, 1) => { + self.bump(); + recover_self_ptr(self)? + } + // `*mut self` and `*const self` + token::BinOp(token::Star) if + self.look_ahead(1, |t| t.is_mutability()) + && is_isolated_self(self, 2) => + { + self.bump(); + self.bump(); + recover_self_ptr(self)? + } + // `self` and `self: TYPE` + token::Ident(..) if is_isolated_self(self, 0) => { + parse_self_possibly_typed(self, Mutability::Immutable)? + } + // `mut self` and `mut self: TYPE` + token::Ident(..) if is_isolated_mut_self(self, 0) => { + self.bump(); + parse_self_possibly_typed(self, Mutability::Mutable)? + } + _ => return Ok(None), + }; + + let eself = source_map::respan(eself_lo.to(eself_hi), eself); + Ok(Some(Param::from_self(ThinVec::default(), eself, eself_ident))) + } + + fn is_named_param(&self) -> bool { + let offset = match self.token.kind { + token::Interpolated(ref nt) => match **nt { + token::NtPat(..) => return self.look_ahead(1, |t| t == &token::Colon), + _ => 0, + } + token::BinOp(token::And) | token::AndAnd => 1, + _ if self.token.is_keyword(kw::Mut) => 1, + _ => 0, + }; + + self.look_ahead(offset, |t| t.is_ident()) && + self.look_ahead(offset + 1, |t| t == &token::Colon) + } + + fn recover_first_param(&mut self) -> &'static str { + match self.parse_outer_attributes() + .and_then(|_| self.parse_self_param()) + .map_err(|mut e| e.cancel()) + { + Ok(Some(_)) => "method", + _ => "function", + } + } +} |