diff options
Diffstat (limited to 'src/librustc_parse/parser/expr.rs')
| -rw-r--r-- | src/librustc_parse/parser/expr.rs | 559 |
1 files changed, 362 insertions, 197 deletions
diff --git a/src/librustc_parse/parser/expr.rs b/src/librustc_parse/parser/expr.rs index 3ae97ed5f88..ca497a3b06f 100644 --- a/src/librustc_parse/parser/expr.rs +++ b/src/librustc_parse/parser/expr.rs @@ -4,19 +4,19 @@ use super::{BlockMode, Parser, PathStyle, Restrictions, TokenType}; use super::{SemiColonMode, SeqSep, TokenExpectType}; use crate::maybe_recover_from_interpolated_ty_qpath; +use rustc_ast::ast::{self, AttrStyle, AttrVec, CaptureBy, Field, Lit, UnOp, DUMMY_NODE_ID}; +use rustc_ast::ast::{AnonConst, BinOp, BinOpKind, FnDecl, FnRetTy, MacCall, Param, Ty, TyKind}; +use rustc_ast::ast::{Arm, Async, BlockCheckMode, Expr, ExprKind, Label, Movability, RangeLimits}; +use rustc_ast::ptr::P; +use rustc_ast::token::{self, Token, TokenKind}; +use rustc_ast::util::classify; +use rustc_ast::util::literal::LitError; +use rustc_ast::util::parser::{prec_let_scrutinee_needs_par, AssocOp, Fixity}; use rustc_ast_pretty::pprust; -use rustc_errors::{Applicability, PResult}; +use rustc_errors::{Applicability, DiagnosticBuilder, PResult}; use rustc_span::source_map::{self, Span, Spanned}; -use rustc_span::symbol::{kw, sym, Symbol}; +use rustc_span::symbol::{kw, sym, Ident, Symbol}; use std::mem; -use syntax::ast::{self, AttrStyle, AttrVec, CaptureBy, Field, Ident, Lit, DUMMY_NODE_ID}; -use syntax::ast::{AnonConst, BinOp, BinOpKind, FnDecl, FnRetTy, Mac, Param, Ty, TyKind, UnOp}; -use syntax::ast::{Arm, Async, BlockCheckMode, Expr, ExprKind, Label, Movability, RangeLimits}; -use syntax::ptr::P; -use syntax::token::{self, Token, TokenKind}; -use syntax::util::classify; -use syntax::util::literal::LitError; -use syntax::util::parser::{prec_let_scrutinee_needs_par, AssocOp, Fixity}; /// Possibly accepts an `token::Interpolated` expression (a pre-parsed expression /// dropped into the token stream, which happens while parsing the result of @@ -50,7 +50,6 @@ macro_rules! maybe_whole_expr { AttrVec::new(), )); } - // N.B., `NtIdent(ident)` is normalized to `Ident` in `fn bump`. _ => {} }; } @@ -97,15 +96,14 @@ impl<'a> Parser<'a> { fn parse_expr_catch_underscore(&mut self) -> PResult<'a, P<Expr>> { match self.parse_expr() { Ok(expr) => Ok(expr), - Err(mut err) => match self.token.kind { - token::Ident(name, false) - if name == kw::Underscore && self.look_ahead(1, |t| t == &token::Comma) => + Err(mut err) => match self.token.ident() { + Some((Ident { name: kw::Underscore, .. }, false)) + if self.look_ahead(1, |t| t == &token::Comma) => { // Special-case handling of `foo(_, _, _)` err.emit(); - let sp = self.token.span; self.bump(); - Ok(self.mk_expr(sp, ExprKind::Err, AttrVec::new())) + Ok(self.mk_expr(self.prev_token.span, ExprKind::Err, AttrVec::new())) } _ => Err(err), }, @@ -166,8 +164,8 @@ impl<'a> Parser<'a> { while let Some(op) = self.check_assoc_op() { // Adjust the span for interpolated LHS to point to the `$lhs` token // and not to what it refers to. - let lhs_span = match self.unnormalized_prev_token.kind { - TokenKind::Interpolated(..) => self.prev_span, + let lhs_span = match self.prev_token.kind { + TokenKind::Interpolated(..) => self.prev_token.span, _ => lhs.span, }; @@ -225,12 +223,8 @@ impl<'a> Parser<'a> { // Make sure that the span of the parent node is larger than the span of lhs and rhs, // including the attributes. - let lhs_span = lhs - .attrs - .iter() - .filter(|a| a.style == AttrStyle::Outer) - .next() - .map_or(lhs_span, |a| a.span); + let lhs_span = + lhs.attrs.iter().find(|a| a.style == AttrStyle::Outer).map_or(lhs_span, |a| a.span); let span = lhs_span.to(rhs.span); lhs = match op { AssocOp::Add @@ -336,21 +330,19 @@ impl<'a> Parser<'a> { /// /// Also performs recovery for `and` / `or` which are mistaken for `&&` and `||` respectively. fn check_assoc_op(&self) -> Option<Spanned<AssocOp>> { - Some(Spanned { - node: match (AssocOp::from_token(&self.token), &self.token.kind) { - (Some(op), _) => op, - (None, token::Ident(sym::and, false)) => { - self.error_bad_logical_op("and", "&&", "conjunction"); - AssocOp::LAnd - } - (None, token::Ident(sym::or, false)) => { - self.error_bad_logical_op("or", "||", "disjunction"); - AssocOp::LOr - } - _ => return None, - }, - span: self.token.span, - }) + let (op, span) = match (AssocOp::from_token(&self.token), self.token.ident()) { + (Some(op), _) => (op, self.token.span), + (None, Some((Ident { name: sym::and, span }, false))) => { + self.error_bad_logical_op("and", "&&", "conjunction"); + (AssocOp::LAnd, span) + } + (None, Some((Ident { name: sym::or, span }, false))) => { + self.error_bad_logical_op("or", "||", "disjunction"); + (AssocOp::LOr, span) + } + _ => return None, + }; + Some(source_map::respan(span, op)) } /// Error on `and` and `or` suggesting `&&` and `||` respectively. @@ -441,7 +433,7 @@ impl<'a> Parser<'a> { let attrs = self.parse_or_use_outer_attributes(attrs)?; let lo = self.token.span; // Note: when adding new unary operators, don't forget to adjust TokenKind::can_begin_expr() - let (hi, ex) = match self.token.kind { + let (hi, ex) = match self.token.uninterpolate().kind { token::Not => self.parse_unary_expr(lo, UnOp::Not), // `!expr` token::Tilde => self.recover_tilde_expr(lo), // `~expr` token::BinOp(token::Minus) => self.parse_unary_expr(lo, UnOp::Neg), // `-expr` @@ -488,7 +480,7 @@ impl<'a> Parser<'a> { } fn is_mistaken_not_ident_negation(&self) -> bool { - let token_cannot_continue_expr = |t: &Token| match t.kind { + let token_cannot_continue_expr = |t: &Token| match t.uninterpolate().kind { // These tokens can start an expression after `!`, but // can't continue an expression after an ident token::Ident(name, is_raw) => token::ident_can_begin_expr(name, t.span, is_raw), @@ -527,8 +519,8 @@ impl<'a> Parser<'a> { ) -> PResult<'a, (Span, P<Expr>)> { expr.map(|e| { ( - match self.unnormalized_prev_token.kind { - TokenKind::Interpolated(..) => self.prev_span, + match self.prev_token.kind { + TokenKind::Interpolated(..) => self.prev_token.span, _ => e.span, }, e, @@ -549,14 +541,13 @@ impl<'a> Parser<'a> { // Save the state of the parser before parsing type normally, in case there is a // LessThan comparison after this cast. let parser_snapshot_before_type = self.clone(); - match self.parse_ty_no_plus() { - Ok(rhs) => Ok(mk_expr(self, rhs)), + let cast_expr = match self.parse_ty_no_plus() { + Ok(rhs) => mk_expr(self, rhs), Err(mut type_err) => { // Rewind to before attempting to parse the type with generics, to recover // from situations like `x as usize < y` in which we first tried to parse // `usize < y` as a type with generic arguments. - let parser_snapshot_after_type = self.clone(); - mem::replace(self, parser_snapshot_before_type); + let parser_snapshot_after_type = mem::replace(self, parser_snapshot_before_type); match self.parse_path(PathStyle::Expr) { Ok(path) => { @@ -568,7 +559,7 @@ impl<'a> Parser<'a> { // example because `parse_ty_no_plus` returns `Err` on keywords, // but `parse_path` returns `Ok` on them due to error recovery. // Return original error and parser state. - mem::replace(self, parser_snapshot_after_type); + *self = parser_snapshot_after_type; return Err(type_err); } }; @@ -604,22 +595,76 @@ impl<'a> Parser<'a> { ) .emit(); - Ok(expr) + expr } Err(mut path_err) => { // Couldn't parse as a path, return original error and parser state. path_err.cancel(); - mem::replace(self, parser_snapshot_after_type); - Err(type_err) + *self = parser_snapshot_after_type; + return Err(type_err); } } } - } + }; + + self.parse_and_disallow_postfix_after_cast(cast_expr) + } + + /// Parses a postfix operators such as `.`, `?`, or index (`[]`) after a cast, + /// then emits an error and returns the newly parsed tree. + /// The resulting parse tree for `&x as T[0]` has a precedence of `((&x) as T)[0]`. + fn parse_and_disallow_postfix_after_cast( + &mut self, + cast_expr: P<Expr>, + ) -> PResult<'a, P<Expr>> { + // Save the memory location of expr before parsing any following postfix operators. + // This will be compared with the memory location of the output expression. + // If they different we can assume we parsed another expression because the existing expression is not reallocated. + let addr_before = &*cast_expr as *const _ as usize; + let span = cast_expr.span; + let with_postfix = self.parse_dot_or_call_expr_with_(cast_expr, span)?; + let changed = addr_before != &*with_postfix as *const _ as usize; + + // Check if an illegal postfix operator has been added after the cast. + // If the resulting expression is not a cast, or has a different memory location, it is an illegal postfix operator. + if !matches!(with_postfix.kind, ExprKind::Cast(_, _) | ExprKind::Type(_, _)) || changed { + let msg = format!( + "casts cannot be followed by {}", + match with_postfix.kind { + ExprKind::Index(_, _) => "indexing", + ExprKind::Try(_) => "?", + ExprKind::Field(_, _) => "a field access", + ExprKind::MethodCall(_, _) => "a method call", + ExprKind::Call(_, _) => "a function call", + ExprKind::Await(_) => "`.await`", + ExprKind::Err => return Ok(with_postfix), + _ => unreachable!("parse_dot_or_call_expr_with_ shouldn't produce this"), + } + ); + let mut err = self.struct_span_err(span, &msg); + // If type ascription is "likely an error", the user will already be getting a useful + // help message, and doesn't need a second. + if self.last_type_ascription.map_or(false, |last_ascription| last_ascription.1) { + self.maybe_annotate_with_ascription(&mut err, false); + } else { + let suggestions = vec![ + (span.shrink_to_lo(), "(".to_string()), + (span.shrink_to_hi(), ")".to_string()), + ]; + err.multipart_suggestion( + "try surrounding the expression in parentheses", + suggestions, + Applicability::MachineApplicable, + ); + } + err.emit(); + }; + Ok(with_postfix) } fn parse_assoc_op_ascribe(&mut self, lhs: P<Expr>, lhs_span: Span) -> PResult<'a, P<Expr>> { let maybe_path = self.could_ascription_be_path(&lhs.kind); - self.last_type_ascription = Some((self.prev_span, maybe_path)); + self.last_type_ascription = Some((self.prev_token.span, maybe_path)); let lhs = self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Type)?; self.sess.gated_spans.gate(sym::type_ascription, lhs.span); Ok(lhs) @@ -628,10 +673,28 @@ impl<'a> Parser<'a> { /// Parse `& mut? <expr>` or `& raw [ const | mut ] <expr>`. fn parse_borrow_expr(&mut self, lo: Span) -> PResult<'a, (Span, ExprKind)> { self.expect_and()?; + let has_lifetime = self.token.is_lifetime() && self.look_ahead(1, |t| t != &token::Colon); + let lifetime = has_lifetime.then(|| self.expect_lifetime()); // For recovery, see below. let (borrow_kind, mutbl) = self.parse_borrow_modifiers(lo); let expr = self.parse_prefix_expr(None); - let (span, expr) = self.interpolated_or_expr_span(expr)?; - Ok((lo.to(span), ExprKind::AddrOf(borrow_kind, mutbl, expr))) + let (hi, expr) = self.interpolated_or_expr_span(expr)?; + let span = lo.to(hi); + if let Some(lt) = lifetime { + self.error_remove_borrow_lifetime(span, lt.ident.span); + } + Ok((span, ExprKind::AddrOf(borrow_kind, mutbl, expr))) + } + + fn error_remove_borrow_lifetime(&self, span: Span, lt_span: Span) { + self.struct_span_err(span, "borrow expressions cannot be annotated with lifetimes") + .span_label(lt_span, "annotated with lifetime here") + .span_suggestion( + lt_span, + "remove the lifetime annotation", + String::new(), + Applicability::MachineApplicable, + ) + .emit(); } /// Parse `mut?` or `raw [ const | mut ]`. @@ -641,7 +704,7 @@ impl<'a> Parser<'a> { let found_raw = self.eat_keyword(kw::Raw); assert!(found_raw); let mutability = self.parse_const_or_mut().unwrap(); - self.sess.gated_spans.gate(sym::raw_ref_op, lo.to(self.prev_span)); + self.sess.gated_spans.gate(sym::raw_ref_op, lo.to(self.prev_token.span)); (ast::BorrowKind::Raw, mutability) } else { // `mut?` @@ -670,25 +733,16 @@ impl<'a> Parser<'a> { expr.map(|mut expr| { attrs.extend::<Vec<_>>(expr.attrs.into()); expr.attrs = attrs; - self.error_attr_on_if_expr(&expr); expr }) }) } - fn error_attr_on_if_expr(&self, expr: &Expr) { - if let (ExprKind::If(..), [a0, ..]) = (&expr.kind, &*expr.attrs) { - // Just point to the first attribute in there... - self.struct_span_err(a0.span, "attributes are not yet allowed on `if` expressions") - .emit(); - } - } - fn parse_dot_or_call_expr_with_(&mut self, mut e: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> { loop { if self.eat(&token::Question) { // `expr?` - e = self.mk_expr(lo.to(self.prev_span), ExprKind::Try(e), AttrVec::new()); + e = self.mk_expr(lo.to(self.prev_token.span), ExprKind::Try(e), AttrVec::new()); continue; } if self.eat(&token::Dot) { @@ -708,7 +762,7 @@ impl<'a> Parser<'a> { } fn parse_dot_suffix_expr(&mut self, lo: Span, base: P<Expr>) -> PResult<'a, P<Expr>> { - match self.token.kind { + match self.token.uninterpolate().kind { token::Ident(..) => self.parse_dot_suffix(base, lo), token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) => { Ok(self.parse_tuple_field_access_expr(lo, base, symbol, suffix)) @@ -740,8 +794,8 @@ impl<'a> Parser<'a> { let fstr = sym.as_str(); let msg = format!("unexpected token: `{}`", sym); - let mut err = self.struct_span_err(self.prev_span, &msg); - err.span_label(self.prev_span, "unexpected token"); + let mut err = self.struct_span_err(self.prev_token.span, &msg); + err.span_label(self.prev_token.span, "unexpected token"); if fstr.chars().all(|x| "0123456789.".contains(x)) { let float = match fstr.parse::<f64>() { @@ -758,10 +812,10 @@ impl<'a> Parser<'a> { s.print_usize(float.trunc() as usize); s.pclose(); s.s.word("."); - s.s.word(fstr.splitn(2, ".").last().unwrap().to_string()) + s.s.word(fstr.splitn(2, '.').last().unwrap().to_string()) }); err.span_suggestion( - lo.to(self.prev_span), + lo.to(self.prev_token.span), "try parenthesizing the first index", sugg, Applicability::MachineApplicable, @@ -777,8 +831,8 @@ impl<'a> Parser<'a> { field: Symbol, suffix: Option<Symbol>, ) -> P<Expr> { - let span = self.token.span; self.bump(); + let span = self.prev_token.span; let field = ExprKind::Field(base, Ident::new(field, span)); self.expect_no_suffix(span, "a tuple index", suffix); self.mk_expr(lo.to(span), field, AttrVec::new()) @@ -787,7 +841,7 @@ impl<'a> Parser<'a> { /// Parse a function call expression, `expr(...)`. fn parse_fn_call_expr(&mut self, lo: Span, fun: P<Expr>) -> P<Expr> { let seq = self.parse_paren_expr_seq().map(|args| { - self.mk_expr(lo.to(self.prev_span), self.mk_call(fun, args), AttrVec::new()) + self.mk_expr(lo.to(self.prev_token.span), self.mk_call(fun, args), AttrVec::new()) }); self.recover_seq_parse_error(token::Paren, lo, seq) } @@ -797,12 +851,12 @@ impl<'a> Parser<'a> { self.bump(); // `[` let index = self.parse_expr()?; self.expect(&token::CloseDelim(token::Bracket))?; - Ok(self.mk_expr(lo.to(self.prev_span), self.mk_index(base, index), AttrVec::new())) + Ok(self.mk_expr(lo.to(self.prev_token.span), self.mk_index(base, index), AttrVec::new())) } /// Assuming we have just parsed `.`, continue parsing into an expression. fn parse_dot_suffix(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> { - if self.token.span.rust_2018() && self.eat_keyword(kw::Await) { + if self.token.uninterpolated_span().rust_2018() && self.eat_keyword(kw::Await) { return self.mk_await_expr(self_arg, lo); } @@ -814,7 +868,7 @@ impl<'a> Parser<'a> { let mut args = self.parse_paren_expr_seq()?; args.insert(0, self_arg); - let span = lo.to(self.prev_span); + let span = lo.to(self.prev_token.span); Ok(self.mk_expr(span, ExprKind::MethodCall(segment, args), AttrVec::new())) } else { // Field access `expr.f` @@ -826,7 +880,7 @@ impl<'a> Parser<'a> { .emit(); } - let span = lo.to(self.prev_span); + let span = lo.to(self.prev_token.span); Ok(self.mk_expr(span, ExprKind::Field(self_arg, segment.ident), AttrVec::new())) } } @@ -865,25 +919,34 @@ impl<'a> Parser<'a> { } else if self.eat_lt() { let (qself, path) = self.parse_qpath(PathStyle::Expr)?; Ok(self.mk_expr(lo.to(path.span), ExprKind::Path(Some(qself), path), attrs)) - } else if self.token.is_path_start() { + } else if self.check_path() { self.parse_path_start_expr(attrs) } else if self.check_keyword(kw::Move) || self.check_keyword(kw::Static) { self.parse_closure_expr(attrs) } else if self.eat_keyword(kw::If) { self.parse_if_expr(attrs) - } else if self.eat_keyword(kw::For) { - self.parse_for_expr(None, self.prev_span, attrs) + } else if self.check_keyword(kw::For) { + if self.choose_generics_over_qpath(1) { + // NOTE(Centril, eddyb): DO NOT REMOVE! Beyond providing parser recovery, + // this is an insurance policy in case we allow qpaths in (tuple-)struct patterns. + // When `for <Foo as Bar>::Proj in $expr $block` is wanted, + // you can disambiguate in favor of a pattern with `(...)`. + self.recover_quantified_closure_expr(attrs) + } else { + assert!(self.eat_keyword(kw::For)); + self.parse_for_expr(None, self.prev_token.span, attrs) + } } else if self.eat_keyword(kw::While) { - self.parse_while_expr(None, self.prev_span, attrs) + self.parse_while_expr(None, self.prev_token.span, attrs) } else if let Some(label) = self.eat_label() { self.parse_labeled_expr(label, attrs) } else if self.eat_keyword(kw::Loop) { - self.parse_loop_expr(None, self.prev_span, attrs) + self.parse_loop_expr(None, self.prev_token.span, attrs) } else if self.eat_keyword(kw::Continue) { let kind = ExprKind::Continue(self.eat_label()); - Ok(self.mk_expr(lo.to(self.prev_span), kind, attrs)) + Ok(self.mk_expr(lo.to(self.prev_token.span), kind, attrs)) } else if self.eat_keyword(kw::Match) { - let match_sp = self.prev_span; + let match_sp = self.prev_token.span; self.parse_match_expr(attrs).map_err(|mut err| { err.span_label(match_sp, "while parsing this match expression"); err @@ -916,7 +979,7 @@ impl<'a> Parser<'a> { // | ^ expected expression self.bump(); Ok(self.mk_expr_err(self.token.span)) - } else if self.token.span.rust_2018() { + } else if self.token.uninterpolated_span().rust_2018() { // `Span::rust_2018()` is somewhat expensive; don't get it repeatedly. if self.check_keyword(kw::Async) { if self.is_async_block() { @@ -926,7 +989,7 @@ impl<'a> Parser<'a> { self.parse_closure_expr(attrs) } } else if self.eat_keyword(kw::Await) { - self.recover_incorrect_await_syntax(lo, self.prev_span, attrs) + self.recover_incorrect_await_syntax(lo, self.prev_token.span, attrs) } else { self.parse_lit_expr(attrs) } @@ -939,10 +1002,10 @@ impl<'a> Parser<'a> { let lo = self.token.span; match self.parse_opt_lit() { Some(literal) => { - let expr = self.mk_expr(lo.to(self.prev_span), ExprKind::Lit(literal), attrs); + let expr = self.mk_expr(lo.to(self.prev_token.span), ExprKind::Lit(literal), attrs); self.maybe_recover_from_bad_qpath(expr, true) } - None => return Err(self.expected_expression_found()), + None => self.try_macro_suggestion(), } } @@ -960,12 +1023,12 @@ impl<'a> Parser<'a> { }; let kind = if es.len() == 1 && !trailing_comma { // `(e)` is parenthesized `e`. - ExprKind::Paren(es.into_iter().nth(0).unwrap()) + ExprKind::Paren(es.into_iter().next().unwrap()) } else { // `(e,)` is a tuple with only one field, `e`. ExprKind::Tup(es) }; - let expr = self.mk_expr(lo.to(self.prev_span), kind, attrs); + let expr = self.mk_expr(lo.to(self.prev_token.span), kind, attrs); self.maybe_recover_from_bad_qpath(expr, true) } @@ -1000,25 +1063,25 @@ impl<'a> Parser<'a> { ExprKind::Array(vec![first_expr]) } }; - let expr = self.mk_expr(lo.to(self.prev_span), kind, attrs); + let expr = self.mk_expr(lo.to(self.prev_token.span), kind, attrs); self.maybe_recover_from_bad_qpath(expr, true) } fn parse_path_start_expr(&mut self, attrs: AttrVec) -> PResult<'a, P<Expr>> { - let lo = self.token.span; let path = self.parse_path(PathStyle::Expr)?; + let lo = path.span; // `!`, as an operator, is prefix, so we know this isn't that. let (hi, kind) = if self.eat(&token::Not) { // MACRO INVOCATION expression - let mac = Mac { + let mac = MacCall { path, args: self.parse_mac_args()?, prior_type_ascription: self.last_type_ascription, }; - (self.prev_span, ExprKind::Mac(mac)) + (self.prev_token.span, ExprKind::MacCall(mac)) } else if self.check(&token::OpenDelim(token::Brace)) { - if let Some(expr) = self.maybe_parse_struct_expr(lo, &path, &attrs) { + if let Some(expr) = self.maybe_parse_struct_expr(&path, &attrs) { return expr; } else { (path.span, ExprKind::Path(None, path)) @@ -1031,26 +1094,44 @@ impl<'a> Parser<'a> { self.maybe_recover_from_bad_qpath(expr, true) } + /// Parse `'label: $expr`. The label is already parsed. fn parse_labeled_expr(&mut self, label: Label, attrs: AttrVec) -> PResult<'a, P<Expr>> { let lo = label.ident.span; - self.expect(&token::Colon)?; - if self.eat_keyword(kw::While) { - return self.parse_while_expr(Some(label), lo, attrs); - } - if self.eat_keyword(kw::For) { - return self.parse_for_expr(Some(label), lo, attrs); - } - if self.eat_keyword(kw::Loop) { - return self.parse_loop_expr(Some(label), lo, attrs); - } - if self.token == token::OpenDelim(token::Brace) { - return self.parse_block_expr(Some(label), lo, BlockCheckMode::Default, attrs); + let label = Some(label); + let ate_colon = self.eat(&token::Colon); + let expr = if self.eat_keyword(kw::While) { + self.parse_while_expr(label, lo, attrs) + } else if self.eat_keyword(kw::For) { + self.parse_for_expr(label, lo, attrs) + } else if self.eat_keyword(kw::Loop) { + self.parse_loop_expr(label, lo, attrs) + } else if self.check(&token::OpenDelim(token::Brace)) || self.token.is_whole_block() { + self.parse_block_expr(label, lo, BlockCheckMode::Default, attrs) + } else { + let msg = "expected `while`, `for`, `loop` or `{` after a label"; + self.struct_span_err(self.token.span, msg).span_label(self.token.span, msg).emit(); + // Continue as an expression in an effort to recover on `'label: non_block_expr`. + self.parse_expr() + }?; + + if !ate_colon { + self.error_labeled_expr_must_be_followed_by_colon(lo, expr.span); } - let msg = "expected `while`, `for`, `loop` or `{` after a label"; - self.struct_span_err(self.token.span, msg).span_label(self.token.span, msg).emit(); - // Continue as an expression in an effort to recover on `'label: non_block_expr`. - self.parse_expr() + Ok(expr) + } + + fn error_labeled_expr_must_be_followed_by_colon(&self, lo: Span, span: Span) { + self.struct_span_err(span, "labeled expression must be followed by `:`") + .span_label(lo, "the label") + .span_suggestion_short( + lo.shrink_to_hi(), + "add `:` after the label", + ": ".to_string(), + Applicability::MachineApplicable, + ) + .note("labels are used before loops and blocks, allowing e.g., `break 'label` to them") + .emit(); } /// Recover on the syntax `do catch { ... }` suggesting `try { ... }` instead. @@ -1060,7 +1141,7 @@ impl<'a> Parser<'a> { self.bump(); // `do` self.bump(); // `catch` - let span_dc = lo.to(self.prev_span); + let span_dc = lo.to(self.prev_token.span); self.struct_span_err(span_dc, "found removed `do catch` syntax") .span_suggestion( span_dc, @@ -1081,15 +1162,15 @@ impl<'a> Parser<'a> { /// Parse `"return" expr?`. fn parse_return_expr(&mut self, attrs: AttrVec) -> PResult<'a, P<Expr>> { - let lo = self.prev_span; + let lo = self.prev_token.span; let kind = ExprKind::Ret(self.parse_expr_opt()?); - let expr = self.mk_expr(lo.to(self.prev_span), kind, attrs); + let expr = self.mk_expr(lo.to(self.prev_token.span), kind, attrs); self.maybe_recover_from_bad_qpath(expr, true) } /// Parse `"('label ":")? break expr?`. fn parse_break_expr(&mut self, attrs: AttrVec) -> PResult<'a, P<Expr>> { - let lo = self.prev_span; + let lo = self.prev_token.span; let label = self.eat_label(); let kind = if self.token != token::OpenDelim(token::Brace) || !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL) @@ -1098,15 +1179,15 @@ impl<'a> Parser<'a> { } else { None }; - let expr = self.mk_expr(lo.to(self.prev_span), ExprKind::Break(label, kind), attrs); + let expr = self.mk_expr(lo.to(self.prev_token.span), ExprKind::Break(label, kind), attrs); self.maybe_recover_from_bad_qpath(expr, true) } /// Parse `"yield" expr?`. fn parse_yield_expr(&mut self, attrs: AttrVec) -> PResult<'a, P<Expr>> { - let lo = self.prev_span; + let lo = self.prev_token.span; let kind = ExprKind::Yield(self.parse_expr_opt()?); - let span = lo.to(self.prev_span); + let span = lo.to(self.prev_token.span); self.sess.gated_spans.gate(sym::generators, span); let expr = self.mk_expr(span, kind, attrs); self.maybe_recover_from_bad_qpath(expr, true) @@ -1302,6 +1383,7 @@ impl<'a> Parser<'a> { } /// Matches `'-' lit | lit` (cf. `ast_validation::AstValidator::check_expr_within_pat`). + /// Keep this in sync with `Token::can_begin_literal_maybe_minus`. pub fn parse_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> { maybe_whole_expr!(self); @@ -1311,7 +1393,11 @@ impl<'a> Parser<'a> { let expr = self.mk_expr(lit.span, ExprKind::Lit(lit), AttrVec::new()); if minus_present { - Ok(self.mk_expr(lo.to(self.prev_span), self.mk_unary(UnOp::Neg, expr), AttrVec::new())) + Ok(self.mk_expr( + lo.to(self.prev_token.span), + self.mk_unary(UnOp::Neg, expr), + AttrVec::new(), + )) } else { Ok(expr) } @@ -1323,21 +1409,43 @@ impl<'a> Parser<'a> { opt_label: Option<Label>, lo: Span, blk_mode: BlockCheckMode, - outer_attrs: AttrVec, + mut attrs: AttrVec, ) -> PResult<'a, P<Expr>> { if let Some(label) = opt_label { self.sess.gated_spans.gate(sym::label_break_value, label.ident.span); } - self.expect(&token::OpenDelim(token::Brace))?; - - let mut attrs = outer_attrs; - attrs.extend(self.parse_inner_attributes()?); + if self.token.is_whole_block() { + self.struct_span_err(self.token.span, "cannot use a `block` macro fragment here") + .span_label(lo.to(self.token.span), "the `block` fragment is within this context") + .emit(); + } - let blk = self.parse_block_tail(lo, blk_mode)?; + let (inner_attrs, blk) = self.parse_block_common(lo, blk_mode)?; + attrs.extend(inner_attrs); Ok(self.mk_expr(blk.span, ExprKind::Block(blk, opt_label), attrs)) } + /// Recover on an explicitly quantified closure expression, e.g., `for<'a> |x: &'a u8| *x + 1`. + fn recover_quantified_closure_expr(&mut self, attrs: AttrVec) -> PResult<'a, P<Expr>> { + let lo = self.token.span; + let _ = self.parse_late_bound_lifetime_defs()?; + let span_for = lo.to(self.prev_token.span); + let closure = self.parse_closure_expr(attrs)?; + + self.struct_span_err(span_for, "cannot introduce explicit parameters for a closure") + .span_label(closure.span, "the parameters are attached to this closure") + .span_suggestion( + span_for, + "remove the parameters", + String::new(), + Applicability::MachineApplicable, + ) + .emit(); + + Ok(self.mk_expr_err(lo.to(closure.span))) + } + /// Parses a closure expression (e.g., `move |args| expr`). fn parse_closure_expr(&mut self, attrs: AttrVec) -> PResult<'a, P<Expr>> { let lo = self.token.span; @@ -1345,16 +1453,19 @@ impl<'a> Parser<'a> { let movability = if self.eat_keyword(kw::Static) { Movability::Static } else { Movability::Movable }; - let asyncness = - if self.token.span.rust_2018() { self.parse_asyncness() } else { Async::No }; - if asyncness.is_async() { + let asyncness = if self.token.uninterpolated_span().rust_2018() { + self.parse_asyncness() + } else { + Async::No + }; + if let Async::Yes { span, .. } = asyncness { // Feature-gate `async ||` closures. - self.sess.gated_spans.gate(sym::async_closure, self.prev_span); + self.sess.gated_spans.gate(sym::async_closure, span); } let capture_clause = self.parse_capture_clause(); let decl = self.parse_fn_block_decl()?; - let decl_hi = self.prev_span; + let decl_hi = self.prev_token.span; let body = match decl.output { FnRetTy::Default(_) => { let restrictions = self.restrictions - Restrictions::STMT_EXPR; @@ -1374,7 +1485,7 @@ impl<'a> Parser<'a> { )) } - /// Parses an optional `move` prefix to a closure lke construct. + /// Parses an optional `move` prefix to a closure-like construct. fn parse_capture_clause(&mut self) -> CaptureBy { if self.eat_keyword(kw::Move) { CaptureBy::Value } else { CaptureBy::Ref } } @@ -1409,7 +1520,7 @@ impl<'a> Parser<'a> { let ty = if self.eat(&token::Colon) { self.parse_ty()? } else { - self.mk_ty(self.prev_span, TyKind::Infer) + self.mk_ty(self.prev_token.span, TyKind::Infer) }; Ok(Param { attrs: attrs.into(), @@ -1423,7 +1534,7 @@ impl<'a> Parser<'a> { /// Parses an `if` expression (`if` token already eaten). fn parse_if_expr(&mut self, attrs: AttrVec) -> PResult<'a, P<Expr>> { - let lo = self.prev_span; + let lo = self.prev_token.span; let cond = self.parse_cond_expr()?; // Verify that the parsed `if` condition makes sense as a condition. If it is a block, then @@ -1433,16 +1544,24 @@ impl<'a> Parser<'a> { let thn = if self.eat_keyword(kw::Else) || !cond.returns() { self.error_missing_if_cond(lo, cond.span) } else { + let attrs = self.parse_outer_attributes()?; // For recovery. let not_block = self.token != token::OpenDelim(token::Brace); - self.parse_block().map_err(|mut err| { + let block = self.parse_block().map_err(|mut err| { if not_block { err.span_label(lo, "this `if` expression has a condition, but no block"); + if let ExprKind::Binary(_, _, ref right) = cond.kind { + if let ExprKind::Block(_, _) = right.kind { + err.help("maybe you forgot the right operand of the condition?"); + } + } } err - })? + })?; + self.error_on_if_block_attrs(lo, false, block.span, &attrs); + block }; let els = if self.eat_keyword(kw::Else) { Some(self.parse_else_expr()?) } else { None }; - Ok(self.mk_expr(lo.to(self.prev_span), ExprKind::If(cond, thn, els), attrs)) + Ok(self.mk_expr(lo.to(self.prev_token.span), ExprKind::If(cond, thn, els), attrs)) } fn error_missing_if_cond(&self, lo: Span, span: Span) -> P<ast::Block> { @@ -1468,7 +1587,7 @@ impl<'a> Parser<'a> { /// Parses a `let $pat = $expr` pseudo-expression. /// The `let` token has already been eaten. fn parse_let_expr(&mut self, attrs: AttrVec) -> PResult<'a, P<Expr>> { - let lo = self.prev_span; + let lo = self.prev_token.span; let pat = self.parse_top_pat(GateOr::No)?; self.expect(&token::Eq)?; let expr = self.with_res(Restrictions::NO_STRUCT_LITERAL, |this| { @@ -1481,12 +1600,40 @@ impl<'a> Parser<'a> { /// Parses an `else { ... }` expression (`else` token already eaten). fn parse_else_expr(&mut self) -> PResult<'a, P<Expr>> { - if self.eat_keyword(kw::If) { - self.parse_if_expr(AttrVec::new()) + let ctx_span = self.prev_token.span; // `else` + let attrs = self.parse_outer_attributes()?; // For recovery. + let expr = if self.eat_keyword(kw::If) { + self.parse_if_expr(AttrVec::new())? } else { let blk = self.parse_block()?; - Ok(self.mk_expr(blk.span, ExprKind::Block(blk, None), AttrVec::new())) - } + self.mk_expr(blk.span, ExprKind::Block(blk, None), AttrVec::new()) + }; + self.error_on_if_block_attrs(ctx_span, true, expr.span, &attrs); + Ok(expr) + } + + fn error_on_if_block_attrs( + &self, + ctx_span: Span, + is_ctx_else: bool, + branch_span: Span, + attrs: &[ast::Attribute], + ) { + let (span, last) = match attrs { + [] => return, + [x0 @ xn] | [x0, .., xn] => (x0.span.to(xn.span), xn.span), + }; + let ctx = if is_ctx_else { "else" } else { "if" }; + self.struct_span_err(last, "outer attributes are not allowed on `if` and `else` branches") + .span_label(branch_span, "the attributes are attached to this branch") + .span_label(ctx_span, format!("the branch belongs to this `{}`", ctx)) + .span_suggestion( + span, + "remove the attributes", + String::new(), + Applicability::MachineApplicable, + ) + .emit(); } /// Parses `for <src_pat> in <src_expr> <src_loop_block>` (`for` token already eaten). @@ -1508,7 +1655,7 @@ impl<'a> Parser<'a> { if !self.eat_keyword(kw::In) { self.error_missing_in_for_loop(); } - self.check_for_for_in_in_typo(self.prev_span); + self.check_for_for_in_in_typo(self.prev_token.span); let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?; let pat = self.recover_parens_around_for_head(pat, &expr, begin_paren); @@ -1517,11 +1664,11 @@ impl<'a> Parser<'a> { attrs.extend(iattrs); let kind = ExprKind::ForLoop(pat, expr, loop_block, opt_label); - Ok(self.mk_expr(lo.to(self.prev_span), kind, attrs)) + Ok(self.mk_expr(lo.to(self.prev_token.span), kind, attrs)) } fn error_missing_in_for_loop(&self) { - let in_span = self.prev_span.between(self.token.span); + let in_span = self.prev_token.span.between(self.token.span); self.struct_span_err(in_span, "missing `in` in `for` loop") .span_suggestion_short( in_span, @@ -1543,7 +1690,7 @@ impl<'a> Parser<'a> { let cond = self.parse_cond_expr()?; let (iattrs, body) = self.parse_inner_attrs_and_block()?; attrs.extend(iattrs); - Ok(self.mk_expr(lo.to(self.prev_span), ExprKind::While(cond, body, opt_label), attrs)) + Ok(self.mk_expr(lo.to(self.prev_token.span), ExprKind::While(cond, body, opt_label), attrs)) } /// Parses `loop { ... }` (`loop` token already eaten). @@ -1555,21 +1702,20 @@ impl<'a> Parser<'a> { ) -> PResult<'a, P<Expr>> { let (iattrs, body) = self.parse_inner_attrs_and_block()?; attrs.extend(iattrs); - Ok(self.mk_expr(lo.to(self.prev_span), ExprKind::Loop(body, opt_label), attrs)) + Ok(self.mk_expr(lo.to(self.prev_token.span), ExprKind::Loop(body, opt_label), attrs)) } fn eat_label(&mut self) -> Option<Label> { self.token.lifetime().map(|ident| { - let span = self.token.span; self.bump(); - Label { ident: Ident::new(ident.name, span) } + Label { ident } }) } /// Parses a `match ... { ... }` expression (`match` token already eaten). fn parse_match_expr(&mut self, mut attrs: AttrVec) -> PResult<'a, P<Expr>> { - let match_span = self.prev_span; - let lo = self.prev_span; + let match_span = self.prev_token.span; + let lo = self.prev_token.span; let scrutinee = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?; if let Err(mut e) = self.expect(&token::OpenDelim(token::Brace)) { if self.token == token::Semi { @@ -1602,7 +1748,7 @@ impl<'a> Parser<'a> { } let hi = self.token.span; self.bump(); - return Ok(self.mk_expr(lo.to(hi), ExprKind::Match(scrutinee, arms), attrs)); + Ok(self.mk_expr(lo.to(hi), ExprKind::Match(scrutinee, arms), attrs)) } pub(super) fn parse_arm(&mut self) -> PResult<'a, Arm> { @@ -1682,8 +1828,10 @@ impl<'a> Parser<'a> { let (iattrs, body) = self.parse_inner_attrs_and_block()?; attrs.extend(iattrs); if self.eat_keyword(kw::Catch) { - let mut error = - self.struct_span_err(self.prev_span, "keyword `catch` cannot follow a `try` block"); + let mut error = self.struct_span_err( + self.prev_token.span, + "keyword `catch` cannot follow a `try` block", + ); error.help("try using `match` on the result of the `try` block instead"); error.emit(); Err(error) @@ -1702,11 +1850,9 @@ impl<'a> Parser<'a> { } fn is_try_block(&self) -> bool { - self.token.is_keyword(kw::Try) && - self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) && - self.token.span.rust_2018() && - // Prevent `while try {} {}`, `if try {} {} else {}`, etc. - !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL) + self.token.is_keyword(kw::Try) + && self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) + && self.token.uninterpolated_span().rust_2018() } /// Parses an `async move? {...}` expression. @@ -1717,7 +1863,7 @@ impl<'a> Parser<'a> { let (iattrs, body) = self.parse_inner_attrs_and_block()?; attrs.extend(iattrs); let kind = ExprKind::Async(capture_clause, DUMMY_NODE_ID, body); - Ok(self.mk_expr(lo.to(self.prev_span), kind, attrs)) + Ok(self.mk_expr(lo.to(self.prev_token.span), kind, attrs)) } fn is_async_block(&self) -> bool { @@ -1749,16 +1895,15 @@ impl<'a> Parser<'a> { fn maybe_parse_struct_expr( &mut self, - lo: Span, path: &ast::Path, attrs: &AttrVec, ) -> Option<PResult<'a, P<Expr>>> { let struct_allowed = !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL); if struct_allowed || self.is_certainly_not_a_block() { // This is a struct literal, but we don't can't accept them here. - let expr = self.parse_struct_expr(lo, path.clone(), attrs.clone()); + let expr = self.parse_struct_expr(path.clone(), attrs.clone()); if let (Ok(expr), false) = (&expr, struct_allowed) { - self.error_struct_lit_not_allowed_here(lo, expr.span); + self.error_struct_lit_not_allowed_here(path.span, expr.span); } return Some(expr); } @@ -1777,20 +1922,26 @@ impl<'a> Parser<'a> { pub(super) fn parse_struct_expr( &mut self, - lo: Span, pth: ast::Path, mut attrs: AttrVec, ) -> PResult<'a, P<Expr>> { - let struct_sp = lo.to(self.prev_span); self.bump(); let mut fields = Vec::new(); let mut base = None; + let mut recover_async = false; attrs.extend(self.parse_inner_attributes()?); + let mut async_block_err = |e: &mut DiagnosticBuilder<'_>, span: Span| { + recover_async = true; + e.span_label(span, "`async` blocks are only allowed in the 2018 edition"); + e.help("set `edition = \"2018\"` in `Cargo.toml`"); + e.note("for more on editions, read https://doc.rust-lang.org/edition-guide"); + }; + while self.token != token::CloseDelim(token::Brace) { if self.eat(&token::DotDot) { - let exp_span = self.prev_span; + let exp_span = self.prev_token.span; match self.parse_expr() { Ok(e) => base = Some(e), Err(mut e) => { @@ -1806,7 +1957,11 @@ impl<'a> Parser<'a> { let parsed_field = match self.parse_field() { Ok(f) => Some(f), Err(mut e) => { - e.span_label(struct_sp, "while parsing this struct"); + if pth == kw::Async { + async_block_err(&mut e, pth.span); + } else { + e.span_label(pth.span, "while parsing this struct"); + } e.emit(); // If the next token is a comma, then try to parse @@ -1830,15 +1985,19 @@ impl<'a> Parser<'a> { } } Err(mut e) => { - e.span_label(struct_sp, "while parsing this struct"); - if let Some(f) = recovery_field { - fields.push(f); - e.span_suggestion( - self.prev_span.shrink_to_hi(), - "try adding a comma", - ",".into(), - Applicability::MachineApplicable, - ); + if pth == kw::Async { + async_block_err(&mut e, pth.span); + } else { + e.span_label(pth.span, "while parsing this struct"); + if let Some(f) = recovery_field { + fields.push(f); + e.span_suggestion( + self.prev_token.span.shrink_to_hi(), + "try adding a comma", + ",".into(), + Applicability::MachineApplicable, + ); + } } e.emit(); self.recover_stmt_(SemiColonMode::Comma, BlockMode::Ignore); @@ -1847,43 +2006,49 @@ impl<'a> Parser<'a> { } } - let span = lo.to(self.token.span); + let span = pth.span.to(self.token.span); self.expect(&token::CloseDelim(token::Brace))?; - Ok(self.mk_expr(span, ExprKind::Struct(pth, fields, base), attrs)) + let expr = if recover_async { ExprKind::Err } else { ExprKind::Struct(pth, fields, base) }; + Ok(self.mk_expr(span, expr, attrs)) } /// Use in case of error after field-looking code: `S { foo: () with a }`. fn find_struct_error_after_field_looking_code(&self) -> Option<Field> { - if let token::Ident(name, _) = self.token.kind { - if !self.token.is_reserved_ident() && self.look_ahead(1, |t| *t == token::Colon) { - let span = self.token.span; - return Some(ast::Field { - ident: Ident::new(name, span), - span, - expr: self.mk_expr_err(span), + match self.token.ident() { + Some((ident, is_raw)) + if (is_raw || !ident.is_reserved()) + && self.look_ahead(1, |t| *t == token::Colon) => + { + Some(ast::Field { + ident, + span: self.token.span, + expr: self.mk_expr_err(self.token.span), is_shorthand: false, attrs: AttrVec::new(), id: DUMMY_NODE_ID, is_placeholder: false, - }); + }) } + _ => None, } - None } fn recover_struct_comma_after_dotdot(&mut self, span: Span) { if self.token != token::Comma { return; } - self.struct_span_err(span.to(self.prev_span), "cannot use a comma after the base struct") - .span_suggestion_short( - self.token.span, - "remove this comma", - String::new(), - Applicability::MachineApplicable, - ) - .note("the base struct must always be the last field") - .emit(); + self.struct_span_err( + span.to(self.prev_token.span), + "cannot use a comma after the base struct", + ) + .span_suggestion_short( + self.token.span, + "remove this comma", + String::new(), + Applicability::MachineApplicable, + ) + .note("the base struct must always be the last field") + .emit(); self.recover_stmt(); } @@ -1973,7 +2138,7 @@ impl<'a> Parser<'a> { limits: RangeLimits, ) -> PResult<'a, ExprKind> { if end.is_none() && limits == RangeLimits::Closed { - self.error_inclusive_range_with_no_end(self.prev_span); + self.error_inclusive_range_with_no_end(self.prev_token.span); Ok(ExprKind::Err) } else { Ok(ExprKind::Range(start, end, limits)) @@ -1997,7 +2162,7 @@ impl<'a> Parser<'a> { } fn mk_await_expr(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> { - let span = lo.to(self.prev_span); + let span = lo.to(self.prev_token.span); let await_expr = self.mk_expr(span, ExprKind::Await(self_arg), AttrVec::new()); self.recover_from_await_method_call(); Ok(await_expr) |