diff options
Diffstat (limited to 'compiler/rustc_parse/src/parser/expr.rs')
| -rw-r--r-- | compiler/rustc_parse/src/parser/expr.rs | 965 |
1 files changed, 639 insertions, 326 deletions
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs index 03c82fbd329..44cb90227e7 100644 --- a/compiler/rustc_parse/src/parser/expr.rs +++ b/compiler/rustc_parse/src/parser/expr.rs @@ -8,6 +8,7 @@ use super::{ use crate::errors; use crate::maybe_recover_from_interpolated_ty_qpath; +use ast::mut_visit::{noop_visit_expr, MutVisitor}; use ast::{Path, PathSegment}; use core::mem; use rustc_ast::ptr::P; @@ -22,10 +23,12 @@ use rustc_ast::{AnonConst, BinOp, BinOpKind, FnDecl, FnRetTy, MacCall, Param, Ty use rustc_ast::{Arm, Async, BlockCheckMode, Expr, ExprKind, Label, Movability, RangeLimits}; use rustc_ast::{ClosureBinder, MetaItemLit, StmtKind}; use rustc_ast_pretty::pprust; +use rustc_data_structures::stack::ensure_sufficient_stack; use rustc_errors::{ AddToDiagnostic, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, IntoDiagnostic, PResult, StashKey, }; +use rustc_macros::Subdiagnostic; use rustc_session::errors::{report_lit_error, ExprParenthesesNeeded}; use rustc_session::lint::builtin::BREAK_WITH_LABEL_AND_LOOP; use rustc_session::lint::BuiltinLintDiagnostics; @@ -91,6 +94,18 @@ impl From<P<Expr>> for LhsExpr { } } +#[derive(Debug)] +enum DestructuredFloat { + /// 1e2 + Single(Symbol, Span), + /// 1. + TrailingDot(Symbol, Span, Span), + /// 1.2 | 1.2e3 + MiddleDot(Symbol, Span, Span, Symbol, Span), + /// Invalid + Error, +} + impl<'a> Parser<'a> { /// Parses an expression. #[inline] @@ -109,8 +124,8 @@ impl<'a> Parser<'a> { self.parse_expr().map(|value| AnonConst { id: DUMMY_NODE_ID, value }) } - fn parse_expr_catch_underscore(&mut self) -> PResult<'a, P<Expr>> { - match self.parse_expr() { + fn parse_expr_catch_underscore(&mut self, restrictions: Restrictions) -> PResult<'a, P<Expr>> { + match self.parse_expr_res(restrictions, None) { Ok(expr) => Ok(expr), Err(mut err) => match self.token.ident() { Some((Ident { name: kw::Underscore, .. }, false)) @@ -128,7 +143,8 @@ impl<'a> Parser<'a> { /// Parses a sequence of expressions delimited by parentheses. fn parse_expr_paren_seq(&mut self) -> PResult<'a, ThinVec<P<Expr>>> { - self.parse_paren_comma_seq(|p| p.parse_expr_catch_underscore()).map(|(r, _)| r) + self.parse_paren_comma_seq(|p| p.parse_expr_catch_underscore(Restrictions::empty())) + .map(|(r, _)| r) } /// Parses an expression, subject to the given restrictions. @@ -174,22 +190,14 @@ impl<'a> Parser<'a> { self.parse_expr_prefix(attrs)? } }; - let last_type_ascription_set = self.last_type_ascription.is_some(); if !self.should_continue_as_assoc_expr(&lhs) { - self.last_type_ascription = None; return Ok(lhs); } self.expected_tokens.push(TokenType::Operator); 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.prev_token.kind { - TokenKind::Interpolated(..) => self.prev_token.span, - _ => lhs.span, - }; - + let lhs_span = self.interpolated_or_expr_span(&lhs); let cur_op_span = self.token.span; let restrictions = if op.node.is_assign_like() { self.restrictions & Restrictions::NO_STRUCT_LITERAL @@ -228,7 +236,7 @@ impl<'a> Parser<'a> { _ => unreachable!(), } .into(); - let invalid = format!("{}=", &sugg); + let invalid = format!("{sugg}="); self.sess.emit_err(errors::InvalidComparisonOperator { span: sp, invalid: invalid.clone(), @@ -301,9 +309,6 @@ impl<'a> Parser<'a> { if op == AssocOp::As { lhs = self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Cast)?; continue; - } else if op == AssocOp::Colon { - lhs = self.parse_assoc_op_ascribe(lhs, lhs_span)?; - continue; } else if op == AssocOp::DotDot || op == AssocOp::DotDotEq { // If we didn't have to handle `x..`/`x..=`, it would be pretty easy to // generalise it to the Fixity::None code. @@ -364,7 +369,7 @@ impl<'a> Parser<'a> { let aopexpr = self.mk_assign_op(source_map::respan(cur_op_span, aop), lhs, rhs); self.mk_expr(span, aopexpr) } - AssocOp::As | AssocOp::Colon | AssocOp::DotDot | AssocOp::DotDotEq => { + AssocOp::As | AssocOp::DotDot | AssocOp::DotDotEq => { self.span_bug(span, "AssocOp should have been handled by special case") } }; @@ -373,9 +378,7 @@ impl<'a> Parser<'a> { break; } } - if last_type_ascription_set { - self.last_type_ascription = None; - } + Ok(lhs) } @@ -621,8 +624,8 @@ impl<'a> Parser<'a> { fn parse_expr_prefix_common(&mut self, lo: Span) -> PResult<'a, (Span, P<Expr>)> { self.bump(); - let expr = self.parse_expr_prefix(None); - let (span, expr) = self.interpolated_or_expr_span(expr)?; + let expr = self.parse_expr_prefix(None)?; + let span = self.interpolated_or_expr_span(&expr); Ok((lo.to(span), expr)) } @@ -697,20 +700,12 @@ impl<'a> Parser<'a> { self.parse_expr_unary(lo, UnOp::Not) } - /// Returns the span of expr, if it was not interpolated or the span of the interpolated token. - fn interpolated_or_expr_span( - &self, - expr: PResult<'a, P<Expr>>, - ) -> PResult<'a, (Span, P<Expr>)> { - expr.map(|e| { - ( - match self.prev_token.kind { - TokenKind::Interpolated(..) => self.prev_token.span, - _ => e.span, - }, - e, - ) - }) + /// Returns the span of expr if it was not interpolated, or the span of the interpolated token. + fn interpolated_or_expr_span(&self, expr: &Expr) -> Span { + match self.prev_token.kind { + TokenKind::Interpolated(..) => self.prev_token.span, + _ => expr.span, + } } fn parse_assoc_op_cast( @@ -743,7 +738,7 @@ impl<'a> Parser<'a> { ( // `foo: ` ExprKind::Path(None, ast::Path { segments, .. }), - TokenKind::Ident(kw::For | kw::Loop | kw::While, false), + token::Ident(kw::For | kw::Loop | kw::While, false), ) if segments.len() == 1 => { let snapshot = self.create_snapshot_for_diagnostic(); let label = Label { @@ -838,33 +833,31 @@ impl<'a> Parser<'a> { &mut self, cast_expr: P<Expr>, ) -> PResult<'a, P<Expr>> { + if let ExprKind::Type(_, _) = cast_expr.kind { + panic!("ExprKind::Type must not be parsed"); + } + let span = cast_expr.span; - let (cast_kind, maybe_ascription_span) = - if let ExprKind::Type(ascripted_expr, _) = &cast_expr.kind { - ("type ascription", Some(ascripted_expr.span.shrink_to_hi().with_hi(span.hi()))) - } else { - ("cast", None) - }; let with_postfix = self.parse_expr_dot_or_call_with_(cast_expr, span)?; // Check if an illegal postfix operator has been added after the cast. // If the resulting expression is not a cast, it is an illegal postfix operator. - if !matches!(with_postfix.kind, ExprKind::Cast(_, _) | ExprKind::Type(_, _)) { + if !matches!(with_postfix.kind, ExprKind::Cast(_, _)) { let msg = format!( - "{cast_kind} cannot be followed by {}", + "cast cannot be followed by {}", match with_postfix.kind { - ExprKind::Index(_, _) => "indexing", + ExprKind::Index(..) => "indexing", ExprKind::Try(_) => "`?`", ExprKind::Field(_, _) => "a field access", ExprKind::MethodCall(_) => "a method call", ExprKind::Call(_, _) => "a function call", - ExprKind::Await(_) => "`.await`", + 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); + let mut err = self.struct_span_err(span, msg); let suggest_parens = |err: &mut Diagnostic| { let suggestions = vec![ @@ -878,44 +871,13 @@ impl<'a> Parser<'a> { ); }; - // 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 if let Some(ascription_span) = maybe_ascription_span { - let is_nightly = self.sess.unstable_features.is_nightly_build(); - if is_nightly { - suggest_parens(&mut err); - } - err.span_suggestion( - ascription_span, - &format!( - "{}remove the type ascription", - if is_nightly { "alternatively, " } else { "" } - ), - "", - if is_nightly { - Applicability::MaybeIncorrect - } else { - Applicability::MachineApplicable - }, - ); - } else { - suggest_parens(&mut err); - } + suggest_parens(&mut err); + 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_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) - } - /// Parse `& mut? <expr>` or `& raw [ const | mut ] <expr>`. fn parse_expr_borrow(&mut self, lo: Span) -> PResult<'a, (Span, ExprKind)> { self.expect_and()?; @@ -926,8 +888,8 @@ impl<'a> Parser<'a> { self.parse_expr_prefix_range(None) } else { self.parse_expr_prefix(None) - }; - let (hi, expr) = self.interpolated_or_expr_span(expr)?; + }?; + let hi = 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); @@ -958,8 +920,8 @@ impl<'a> Parser<'a> { fn parse_expr_dot_or_call(&mut self, attrs: Option<AttrWrapper>) -> PResult<'a, P<Expr>> { let attrs = self.parse_or_use_outer_attributes(attrs)?; self.collect_tokens_for_expr(attrs, |this, attrs| { - let base = this.parse_expr_bottom(); - let (span, base) = this.interpolated_or_expr_span(base)?; + let base = this.parse_expr_bottom()?; + let span = this.interpolated_or_expr_span(&base); this.parse_expr_dot_or_call_with(base, span, attrs) }) } @@ -1010,7 +972,7 @@ impl<'a> Parser<'a> { }; if has_dot { // expr.f - e = self.parse_expr_dot_suffix(lo, e)?; + e = self.parse_dot_suffix_expr(lo, e)?; continue; } if self.expr_is_complete(&e) { @@ -1024,13 +986,7 @@ impl<'a> Parser<'a> { } } - fn look_ahead_type_ascription_as_field(&mut self) -> bool { - self.look_ahead(1, |t| t.is_ident()) - && self.look_ahead(2, |t| t == &token::Colon) - && self.look_ahead(3, |t| t.can_begin_expr()) - } - - fn parse_expr_dot_suffix(&mut self, lo: Span, base: P<Expr>) -> PResult<'a, P<Expr>> { + fn parse_dot_suffix_expr(&mut self, lo: Span, base: P<Expr>) -> PResult<'a, P<Expr>> { match self.token.uninterpolate().kind { token::Ident(..) => self.parse_dot_suffix(base, lo), token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) => { @@ -1047,9 +1003,16 @@ impl<'a> Parser<'a> { } fn error_unexpected_after_dot(&self) { - // FIXME Could factor this out into non_fatal_unexpected or something. let actual = pprust::token_to_string(&self.token); - self.sess.emit_err(errors::UnexpectedTokenAfterDot { span: self.token.span, actual }); + let span = self.token.span; + let sm = self.sess.source_map(); + let (span, actual) = match (&self.token.kind, self.subparser_name) { + (token::Eof, Some(_)) if let Ok(actual) = sm.span_to_snippet(sm.next_point(span)) => { + (span.shrink_to_hi(), actual.into()) + } + _ => (span, actual), + }; + self.sess.emit_err(errors::UnexpectedTokenAfterDot { span, actual }); } // We need an identifier or integer, but the next token is a float. @@ -1059,13 +1022,8 @@ impl<'a> Parser<'a> { // support pushing "future tokens" (would be also helpful to `break_and_eat`), or // we should break everything including floats into more basic proc-macro style // tokens in the lexer (probably preferable). - fn parse_expr_tuple_field_access_float( - &mut self, - lo: Span, - base: P<Expr>, - float: Symbol, - suffix: Option<Symbol>, - ) -> P<Expr> { + // See also `TokenKind::break_two_token_op` which does similar splitting of `>>` into `>`. + fn break_up_float(&mut self, float: Symbol) -> DestructuredFloat { #[derive(Debug)] enum FloatComponent { IdentLike(String), @@ -1085,7 +1043,7 @@ impl<'a> Parser<'a> { } components.push(Punct(c)); } else { - panic!("unexpected character in a float token: {:?}", c) + panic!("unexpected character in a float token: {c:?}") } } if !ident_like.is_empty() { @@ -1102,7 +1060,7 @@ impl<'a> Parser<'a> { match &*components { // 1e2 [IdentLike(i)] => { - self.parse_expr_tuple_field_access(lo, base, Symbol::intern(&i), suffix, None) + DestructuredFloat::Single(Symbol::intern(&i), span) } // 1. [IdentLike(i), Punct('.')] => { @@ -1114,11 +1072,8 @@ impl<'a> Parser<'a> { } else { (span, span) }; - assert!(suffix.is_none()); let symbol = Symbol::intern(&i); - self.token = Token::new(token::Ident(symbol, false), ident_span); - let next_token = (Token::new(token::Dot, dot_span), self.token_spacing); - self.parse_expr_tuple_field_access(lo, base, symbol, None, Some(next_token)) + DestructuredFloat::TrailingDot(symbol, ident_span, dot_span) } // 1.2 | 1.2e3 [IdentLike(i1), Punct('.'), IdentLike(i2)] => { @@ -1134,16 +1089,8 @@ impl<'a> Parser<'a> { (span, span, span) }; let symbol1 = Symbol::intern(&i1); - self.token = Token::new(token::Ident(symbol1, false), ident1_span); - // This needs to be `Spacing::Alone` to prevent regressions. - // See issue #76399 and PR #76285 for more details - let next_token1 = (Token::new(token::Dot, dot_span), Spacing::Alone); - let base1 = - self.parse_expr_tuple_field_access(lo, base, symbol1, None, Some(next_token1)); let symbol2 = Symbol::intern(&i2); - let next_token2 = Token::new(token::Ident(symbol2, false), ident2_span); - self.bump_with((next_token2, self.token_spacing)); // `.` - self.parse_expr_tuple_field_access(lo, base1, symbol2, suffix, None) + DestructuredFloat::MiddleDot(symbol1, ident1_span, dot_span, symbol2, ident2_span) } // 1e+ | 1e- (recovered) [IdentLike(_), Punct('+' | '-')] | @@ -1155,12 +1102,83 @@ impl<'a> Parser<'a> { [IdentLike(_), Punct('.'), IdentLike(_), Punct('+' | '-'), IdentLike(_)] => { // See the FIXME about `TokenCursor` above. self.error_unexpected_after_dot(); - base + DestructuredFloat::Error + } + _ => panic!("unexpected components in a float token: {components:?}"), + } + } + + fn parse_expr_tuple_field_access_float( + &mut self, + lo: Span, + base: P<Expr>, + float: Symbol, + suffix: Option<Symbol>, + ) -> P<Expr> { + match self.break_up_float(float) { + // 1e2 + DestructuredFloat::Single(sym, _sp) => { + self.parse_expr_tuple_field_access(lo, base, sym, suffix, None) + } + // 1. + DestructuredFloat::TrailingDot(sym, ident_span, dot_span) => { + assert!(suffix.is_none()); + self.token = Token::new(token::Ident(sym, false), ident_span); + let next_token = (Token::new(token::Dot, dot_span), self.token_spacing); + self.parse_expr_tuple_field_access(lo, base, sym, None, Some(next_token)) + } + // 1.2 | 1.2e3 + DestructuredFloat::MiddleDot(symbol1, ident1_span, dot_span, symbol2, ident2_span) => { + self.token = Token::new(token::Ident(symbol1, false), ident1_span); + // This needs to be `Spacing::Alone` to prevent regressions. + // See issue #76399 and PR #76285 for more details + let next_token1 = (Token::new(token::Dot, dot_span), Spacing::Alone); + let base1 = + self.parse_expr_tuple_field_access(lo, base, symbol1, None, Some(next_token1)); + let next_token2 = Token::new(token::Ident(symbol2, false), ident2_span); + self.bump_with((next_token2, self.token_spacing)); // `.` + self.parse_expr_tuple_field_access(lo, base1, symbol2, suffix, None) } - _ => panic!("unexpected components in a float token: {:?}", components), + DestructuredFloat::Error => base, } } + fn parse_field_name_maybe_tuple(&mut self) -> PResult<'a, ThinVec<Ident>> { + let token::Literal(token::Lit { kind: token::Float, symbol, suffix }) = self.token.kind + else { + return Ok(thin_vec![self.parse_field_name()?]); + }; + Ok(match self.break_up_float(symbol) { + // 1e2 + DestructuredFloat::Single(sym, sp) => { + self.bump(); + thin_vec![Ident::new(sym, sp)] + } + // 1. + DestructuredFloat::TrailingDot(sym, sym_span, dot_span) => { + assert!(suffix.is_none()); + // Analogous to `Self::break_and_eat` + self.break_last_token = true; + // This might work, in cases like `1. 2`, and might not, + // in cases like `offset_of!(Ty, 1.)`. It depends on what comes + // after the float-like token, and therefore we have to make + // the other parts of the parser think that there is a dot literal. + self.token = Token::new(token::Ident(sym, false), sym_span); + self.bump_with((Token::new(token::Dot, dot_span), self.token_spacing)); + thin_vec![Ident::new(sym, sym_span)] + } + // 1.2 | 1.2e3 + DestructuredFloat::MiddleDot(symbol1, ident1_span, _dot_span, symbol2, ident2_span) => { + self.bump(); + thin_vec![Ident::new(symbol1, ident1_span), Ident::new(symbol2, ident2_span)] + } + DestructuredFloat::Error => { + self.bump(); + thin_vec![Ident::new(symbol, self.prev_token.span)] + } + }) + } + fn parse_expr_tuple_field_access( &mut self, lo: Span, @@ -1183,9 +1201,7 @@ impl<'a> Parser<'a> { /// Parse a function call expression, `expr(...)`. fn parse_expr_fn_call(&mut self, lo: Span, fun: P<Expr>) -> P<Expr> { - let snapshot = if self.token.kind == token::OpenDelim(Delimiter::Parenthesis) - && self.look_ahead_type_ascription_as_field() - { + let snapshot = if self.token.kind == token::OpenDelim(Delimiter::Parenthesis) { Some((self.create_snapshot_for_diagnostic(), fun.kind.clone())) } else { None @@ -1216,7 +1232,6 @@ impl<'a> Parser<'a> { if !self.may_recover() { return None; } - match (seq.as_mut(), snapshot) { (Err(err), Some((mut snapshot, ExprKind::Path(None, path)))) => { snapshot.bump(); // `(` @@ -1229,11 +1244,15 @@ impl<'a> Parser<'a> { self.restore_snapshot(snapshot); let close_paren = self.prev_token.span; let span = lo.to(close_paren); + // filter shorthand fields + let fields: Vec<_> = + fields.into_iter().filter(|field| !field.is_shorthand).collect(); + if !fields.is_empty() && // `token.kind` should not be compared here. // This is because the `snapshot.token.kind` is treated as the same as // that of the open delim in `TokenTreesReader::parse_token_tree`, even if they are different. - self.span_to_snippet(close_paren).map_or(false, |snippet| snippet == ")") + self.span_to_snippet(close_paren).is_ok_and(|snippet| snippet == ")") { let mut replacement_err = errors::ParenthesesWithStructFields { span, @@ -1260,9 +1279,7 @@ impl<'a> Parser<'a> { return Some(self.mk_expr_err(span)); } Ok(_) => {} - Err(mut err) => { - err.emit(); - } + Err(err) => err.cancel(), } } _ => {} @@ -1278,12 +1295,15 @@ impl<'a> Parser<'a> { let index = self.parse_expr()?; self.suggest_missing_semicolon_before_array(prev_span, open_delim_span)?; self.expect(&token::CloseDelim(Delimiter::Bracket))?; - Ok(self.mk_expr(lo.to(self.prev_token.span), self.mk_index(base, index))) + Ok(self.mk_expr( + lo.to(self.prev_token.span), + self.mk_index(base, index, open_delim_span.to(self.prev_token.span)), + )) } /// 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.uninterpolated_span().rust_2018() && self.eat_keyword(kw::Await) { + if self.token.uninterpolated_span().at_least_rust_2018() && self.eat_keyword(kw::Await) { return Ok(self.mk_await_expr(self_arg, lo)); } @@ -1329,106 +1349,113 @@ impl<'a> Parser<'a> { // Outer attributes are already parsed and will be // added to the return value after the fact. - // Note: when adding new syntax here, don't forget to adjust `TokenKind::can_begin_expr()`. - let lo = self.token.span; - if let token::Literal(_) = self.token.kind { - // This match arm is a special-case of the `_` match arm below and - // could be removed without changing functionality, but it's faster - // to have it here, especially for programs with large constants. - self.parse_expr_lit() - } else if self.check(&token::OpenDelim(Delimiter::Parenthesis)) { - self.parse_expr_tuple_parens() - } else if self.check(&token::OpenDelim(Delimiter::Brace)) { - self.parse_expr_block(None, lo, BlockCheckMode::Default) - } else if self.check(&token::BinOp(token::Or)) || self.check(&token::OrOr) { - self.parse_expr_closure().map_err(|mut err| { - // If the input is something like `if a { 1 } else { 2 } | if a { 3 } else { 4 }` - // then suggest parens around the lhs. - if let Some(sp) = self.sess.ambiguous_block_expr_parse.borrow().get(&lo) { - err.subdiagnostic(ExprParenthesesNeeded::surrounding(*sp)); + let restrictions = self.restrictions; + self.with_res(restrictions - Restrictions::ALLOW_LET, |this| { + // Note: when adding new syntax here, don't forget to adjust `TokenKind::can_begin_expr()`. + let lo = this.token.span; + if let token::Literal(_) = this.token.kind { + // This match arm is a special-case of the `_` match arm below and + // could be removed without changing functionality, but it's faster + // to have it here, especially for programs with large constants. + this.parse_expr_lit() + } else if this.check(&token::OpenDelim(Delimiter::Parenthesis)) { + this.parse_expr_tuple_parens(restrictions) + } else if this.check(&token::OpenDelim(Delimiter::Brace)) { + this.parse_expr_block(None, lo, BlockCheckMode::Default) + } else if this.check(&token::BinOp(token::Or)) || this.check(&token::OrOr) { + this.parse_expr_closure().map_err(|mut err| { + // If the input is something like `if a { 1 } else { 2 } | if a { 3 } else { 4 }` + // then suggest parens around the lhs. + if let Some(sp) = this.sess.ambiguous_block_expr_parse.borrow().get(&lo) { + err.subdiagnostic(ExprParenthesesNeeded::surrounding(*sp)); + } + err + }) + } else if this.check(&token::OpenDelim(Delimiter::Bracket)) { + this.parse_expr_array_or_repeat(Delimiter::Bracket) + } else if this.is_builtin() { + this.parse_expr_builtin() + } else if this.check_path() { + this.parse_expr_path_start() + } else if this.check_keyword(kw::Move) + || this.check_keyword(kw::Static) + || this.check_const_closure() + { + this.parse_expr_closure() + } else if this.eat_keyword(kw::If) { + this.parse_expr_if() + } else if this.check_keyword(kw::For) { + if this.choose_generics_over_qpath(1) { + this.parse_expr_closure() + } else { + assert!(this.eat_keyword(kw::For)); + this.parse_expr_for(None, this.prev_token.span) } - err - }) - } else if self.check(&token::OpenDelim(Delimiter::Bracket)) { - self.parse_expr_array_or_repeat(Delimiter::Bracket) - } else if self.check_path() { - self.parse_expr_path_start() - } else if self.check_keyword(kw::Move) - || self.check_keyword(kw::Static) - || self.check_const_closure() - { - self.parse_expr_closure() - } else if self.eat_keyword(kw::If) { - self.parse_expr_if() - } else if self.check_keyword(kw::For) { - if self.choose_generics_over_qpath(1) { - self.parse_expr_closure() - } else { - assert!(self.eat_keyword(kw::For)); - self.parse_expr_for(None, self.prev_token.span) - } - } else if self.eat_keyword(kw::While) { - self.parse_expr_while(None, self.prev_token.span) - } else if let Some(label) = self.eat_label() { - self.parse_expr_labeled(label, true) - } else if self.eat_keyword(kw::Loop) { - let sp = self.prev_token.span; - self.parse_expr_loop(None, self.prev_token.span).map_err(|mut err| { - err.span_label(sp, "while parsing this `loop` expression"); - err - }) - } else if self.eat_keyword(kw::Match) { - let match_sp = self.prev_token.span; - self.parse_expr_match().map_err(|mut err| { - err.span_label(match_sp, "while parsing this `match` expression"); - err - }) - } else if self.eat_keyword(kw::Unsafe) { - let sp = self.prev_token.span; - self.parse_expr_block(None, lo, BlockCheckMode::Unsafe(ast::UserProvided)).map_err( - |mut err| { - err.span_label(sp, "while parsing this `unsafe` expression"); + } else if this.eat_keyword(kw::While) { + this.parse_expr_while(None, this.prev_token.span) + } else if let Some(label) = this.eat_label() { + this.parse_expr_labeled(label, true) + } else if this.eat_keyword(kw::Loop) { + let sp = this.prev_token.span; + this.parse_expr_loop(None, this.prev_token.span).map_err(|mut err| { + err.span_label(sp, "while parsing this `loop` expression"); err - }, - ) - } else if self.check_inline_const(0) { - self.parse_const_block(lo.to(self.token.span), false) - } else if self.may_recover() && self.is_do_catch_block() { - self.recover_do_catch() - } else if self.is_try_block() { - self.expect_keyword(kw::Try)?; - self.parse_try_block(lo) - } else if self.eat_keyword(kw::Return) { - self.parse_expr_return() - } else if self.eat_keyword(kw::Continue) { - self.parse_expr_continue(lo) - } else if self.eat_keyword(kw::Break) { - self.parse_expr_break() - } else if self.eat_keyword(kw::Yield) { - self.parse_expr_yield() - } else if self.is_do_yeet() { - self.parse_expr_yeet() - } else if self.check_keyword(kw::Let) { - self.parse_expr_let() - } else if self.eat_keyword(kw::Underscore) { - Ok(self.mk_expr(self.prev_token.span, ExprKind::Underscore)) - } 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() { - // Check for `async {` and `async move {`. - self.parse_async_block() + }) + } else if this.eat_keyword(kw::Match) { + let match_sp = this.prev_token.span; + this.parse_expr_match().map_err(|mut err| { + err.span_label(match_sp, "while parsing this `match` expression"); + err + }) + } else if this.eat_keyword(kw::Unsafe) { + let sp = this.prev_token.span; + this.parse_expr_block(None, lo, BlockCheckMode::Unsafe(ast::UserProvided)).map_err( + |mut err| { + err.span_label(sp, "while parsing this `unsafe` expression"); + err + }, + ) + } else if this.check_inline_const(0) { + this.parse_const_block(lo.to(this.token.span), false) + } else if this.may_recover() && this.is_do_catch_block() { + this.recover_do_catch() + } else if this.is_try_block() { + this.expect_keyword(kw::Try)?; + this.parse_try_block(lo) + } else if this.eat_keyword(kw::Return) { + this.parse_expr_return() + } else if this.eat_keyword(kw::Continue) { + this.parse_expr_continue(lo) + } else if this.eat_keyword(kw::Break) { + this.parse_expr_break() + } else if this.eat_keyword(kw::Yield) { + this.parse_expr_yield() + } else if this.is_do_yeet() { + this.parse_expr_yeet() + } else if this.eat_keyword(kw::Become) { + this.parse_expr_become() + } else if this.check_keyword(kw::Let) { + this.parse_expr_let(restrictions) + } else if this.eat_keyword(kw::Underscore) { + Ok(this.mk_expr(this.prev_token.span, ExprKind::Underscore)) + } else if this.token.uninterpolated_span().at_least_rust_2018() { + // `Span:.at_least_rust_2018()` is somewhat expensive; don't get it repeatedly. + if this.check_keyword(kw::Async) { + if this.is_async_block() { + // Check for `async {` and `async move {`. + this.parse_async_block() + } else { + this.parse_expr_closure() + } + } else if this.eat_keyword(kw::Await) { + this.recover_incorrect_await_syntax(lo, this.prev_token.span) } else { - self.parse_expr_closure() + this.parse_expr_lit() } - } else if self.eat_keyword(kw::Await) { - self.recover_incorrect_await_syntax(lo, self.prev_token.span) } else { - self.parse_expr_lit() + this.parse_expr_lit() } - } else { - self.parse_expr_lit() - } + }) } fn parse_expr_lit(&mut self) -> PResult<'a, P<Expr>> { @@ -1442,13 +1469,13 @@ impl<'a> Parser<'a> { } } - fn parse_expr_tuple_parens(&mut self) -> PResult<'a, P<Expr>> { + fn parse_expr_tuple_parens(&mut self, restrictions: Restrictions) -> PResult<'a, P<Expr>> { let lo = self.token.span; self.expect(&token::OpenDelim(Delimiter::Parenthesis))?; let (es, trailing_comma) = match self.parse_seq_to_end( &token::CloseDelim(Delimiter::Parenthesis), SeqSep::trailing_allowed(token::Comma), - |p| p.parse_expr_catch_underscore(), + |p| p.parse_expr_catch_underscore(restrictions.intersection(Restrictions::ALLOW_LET)), ) { Ok(x) => x, Err(err) => { @@ -1499,8 +1526,19 @@ impl<'a> Parser<'a> { } fn parse_expr_path_start(&mut self) -> PResult<'a, P<Expr>> { + let maybe_eq_tok = self.prev_token.clone(); let (qself, path) = if self.eat_lt() { - let (qself, path) = self.parse_qpath(PathStyle::Expr)?; + let lt_span = self.prev_token.span; + let (qself, path) = self.parse_qpath(PathStyle::Expr).map_err(|mut err| { + // Suggests using '<=' if there is an error parsing qpath when the previous token + // is an '=' token. Only emits suggestion if the '<' token and '=' token are + // directly adjacent (i.e. '=<') + if maybe_eq_tok.kind == TokenKind::Eq && maybe_eq_tok.span.hi() == lt_span.lo() { + let eq_lt = maybe_eq_tok.span.to(lt_span); + err.span_suggestion(eq_lt, "did you mean", "<=", Applicability::Unspecified); + } + err + })?; (Some(qself), path) } else { (None, self.parse_path(PathStyle::Expr)?) @@ -1513,11 +1551,7 @@ impl<'a> Parser<'a> { self.sess.emit_err(errors::MacroInvocationWithQualifiedPath(path.span)); } let lo = path.span; - let mac = P(MacCall { - path, - args: self.parse_delim_args()?, - prior_type_ascription: self.last_type_ascription, - }); + let mac = P(MacCall { path, args: self.parse_delim_args()? }); (lo.to(self.prev_token.span), ExprKind::MacCall(mac)) } else if self.check(&token::OpenDelim(Delimiter::Brace)) && let Some(expr) = self.maybe_parse_struct_expr(&qself, &path) @@ -1535,7 +1569,7 @@ impl<'a> Parser<'a> { } /// Parse `'label: $expr`. The label is already parsed. - fn parse_expr_labeled( + pub(super) fn parse_expr_labeled( &mut self, label_: Label, mut consume_colon: bool, @@ -1556,7 +1590,7 @@ impl<'a> Parser<'a> { } else if !ate_colon && self.may_recover() && (matches!(self.token.kind, token::CloseDelim(_) | token::Comma) - || self.token.is_op()) + || self.token.is_punct()) { let (lit, _) = self.recover_unclosed_char(label_.ident, Parser::mk_token_lit_char, |self_| { @@ -1714,6 +1748,16 @@ impl<'a> Parser<'a> { self.maybe_recover_from_bad_qpath(expr) } + /// Parse `"become" expr`, with `"become"` token already eaten. + fn parse_expr_become(&mut self) -> PResult<'a, P<Expr>> { + let lo = self.prev_token.span; + let kind = ExprKind::Become(self.parse_expr()?); + let span = lo.to(self.prev_token.span); + self.sess.gated_spans.gate(sym::explicit_tail_calls, span); + let expr = self.mk_expr(span, kind); + self.maybe_recover_from_bad_qpath(expr) + } + /// Parse `"break" (('label (:? expr)?) | expr?)` with `"break"` token already eaten. /// If the label is followed immediately by a `:` token, the label and `:` are /// parsed as part of the expression (i.e. a labeled loop). The language team has @@ -1725,7 +1769,9 @@ impl<'a> Parser<'a> { fn parse_expr_break(&mut self) -> PResult<'a, P<Expr>> { let lo = self.prev_token.span; let mut label = self.eat_label(); - let kind = if self.token == token::Colon && let Some(label) = label.take() { + let kind = if self.token == token::Colon + && let Some(label) = label.take() + { // The value expression can be a labeled loop, see issue #86948, e.g.: // `loop { break 'label: loop { break 'label 42; }; }` let lexpr = self.parse_expr_labeled(label, true)?; @@ -1807,6 +1853,62 @@ impl<'a> Parser<'a> { self.maybe_recover_from_bad_qpath(expr) } + /// Parse `builtin # ident(args,*)`. + fn parse_expr_builtin(&mut self) -> PResult<'a, P<Expr>> { + self.parse_builtin(|this, lo, ident| { + if ident.name == sym::offset_of { + return Ok(Some(this.parse_expr_offset_of(lo)?)); + } + + Ok(None) + }) + } + + pub(crate) fn parse_builtin<T>( + &mut self, + parse: impl FnOnce(&mut Parser<'a>, Span, Ident) -> PResult<'a, Option<T>>, + ) -> PResult<'a, T> { + let lo = self.token.span; + + self.bump(); // `builtin` + self.bump(); // `#` + + let Some((ident, false)) = self.token.ident() else { + let err = errors::ExpectedBuiltinIdent { span: self.token.span } + .into_diagnostic(&self.sess.span_diagnostic); + return Err(err); + }; + self.sess.gated_spans.gate(sym::builtin_syntax, ident.span); + self.bump(); + + self.expect(&TokenKind::OpenDelim(Delimiter::Parenthesis))?; + let ret = if let Some(res) = parse(self, lo, ident)? { + Ok(res) + } else { + let err = errors::UnknownBuiltinConstruct { span: lo.to(ident.span), name: ident.name } + .into_diagnostic(&self.sess.span_diagnostic); + return Err(err); + }; + self.expect(&TokenKind::CloseDelim(Delimiter::Parenthesis))?; + + ret + } + + pub(crate) fn parse_expr_offset_of(&mut self, lo: Span) -> PResult<'a, P<Expr>> { + let container = self.parse_ty()?; + self.expect(&TokenKind::Comma)?; + + let seq_sep = SeqSep { sep: Some(token::Dot), trailing_sep_allowed: false }; + let (fields, _trailing, _recovered) = self.parse_seq_to_before_end( + &TokenKind::CloseDelim(Delimiter::Parenthesis), + seq_sep, + Parser::parse_field_name_maybe_tuple, + )?; + let fields = fields.into_iter().flatten().collect::<Vec<_>>(); + let span = lo.to(self.token.span); + Ok(self.mk_expr(span, ExprKind::OffsetOf(container, fields.into()))) + } + /// Returns a string literal if the next token is a string literal. /// In case of error returns `Some(lit)` if the next token is a literal with a wrong kind, /// and returns `None` if the next token is not literal at all. @@ -1855,7 +1957,7 @@ impl<'a> Parser<'a> { let token = self.token.clone(); let err = |self_: &Self| { let msg = format!("unexpected token: {}", super::token_descr(&token)); - self_.struct_span_err(token.span, &msg) + self_.struct_span_err(token.span, msg) }; // On an error path, eagerly consider a lifetime to be an unclosed character lit if self.token.is_lifetime() { @@ -1922,6 +2024,7 @@ impl<'a> Parser<'a> { let recovered = self.recover_after_dot(); let token = recovered.as_ref().unwrap_or(&self.token); let span = token.span; + token::Lit::from_token(token).map(|token_lit| { self.bump(); (token_lit, span) @@ -1934,17 +2037,14 @@ impl<'a> Parser<'a> { let recovered = self.recover_after_dot(); let token = recovered.as_ref().unwrap_or(&self.token); match token::Lit::from_token(token) { - Some(token_lit) => { - match MetaItemLit::from_token_lit(token_lit, token.span) { + Some(lit) => { + match MetaItemLit::from_token_lit(lit, token.span) { Ok(lit) => { self.bump(); Some(lit) } Err(err) => { - let span = token.span; - let token::Literal(lit) = token.kind else { - unreachable!(); - }; + let span = token.uninterpolated_span(); self.bump(); report_lit_error(&self.sess, err, lit, span); // Pack possible quotes and prefixes from the original literal into @@ -2057,7 +2157,7 @@ impl<'a> Parser<'a> { // Therefore, `token.kind` should not be compared here. if snapshot .span_to_snippet(snapshot.token.span) - .map_or(false, |snippet| snippet == "]") => + .is_ok_and(|snippet| snippet == "]") => { return Err(errors::MissingSemicolonBeforeArray { open_delim: open_delim_span, @@ -2088,6 +2188,10 @@ impl<'a> Parser<'a> { self.sess.emit_err(errors::InvalidBlockMacroSegment { span: self.token.span, context: lo.to(self.token.span), + wrap: errors::WrapInExplicitBlock { + lo: self.token.span.shrink_to_lo(), + hi: self.token.span.shrink_to_hi(), + }, }); } @@ -2105,6 +2209,7 @@ impl<'a> Parser<'a> { fn parse_expr_closure(&mut self) -> PResult<'a, P<Expr>> { let lo = self.token.span; + let before = self.prev_token.clone(); let binder = if self.check_keyword(kw::For) { let lo = self.token.span; let lifetime_defs = self.parse_late_bound_lifetime_defs()?; @@ -2122,7 +2227,7 @@ impl<'a> Parser<'a> { let movability = if self.eat_keyword(kw::Static) { Movability::Static } else { Movability::Movable }; - let asyncness = if self.token.uninterpolated_span().rust_2018() { + let asyncness = if self.token.uninterpolated_span().at_least_rust_2018() { self.parse_asyncness(Case::Sensitive) } else { Async::No @@ -2133,8 +2238,14 @@ impl<'a> Parser<'a> { let decl_hi = self.prev_token.span; let mut body = match fn_decl.output { FnRetTy::Default(_) => { - let restrictions = self.restrictions - Restrictions::STMT_EXPR; - self.parse_expr_res(restrictions, None)? + let restrictions = + self.restrictions - Restrictions::STMT_EXPR - Restrictions::ALLOW_LET; + let prev = self.prev_token.clone(); + let token = self.token.clone(); + match self.parse_expr_res(restrictions, None) { + Ok(expr) => expr, + Err(err) => self.recover_closure_body(err, before, prev, token, lo, decl_hi)?, + } } _ => { // If an explicit return type is given, require a block to appear (RFC 968). @@ -2230,11 +2341,11 @@ impl<'a> Parser<'a> { let lo = self.token.span; let attrs = self.parse_outer_attributes()?; self.collect_tokens_trailing_token(attrs, ForceCollect::No, |this, attrs| { - let pat = this.parse_pat_no_top_alt(Some(Expected::ParameterName))?; + let pat = this.parse_pat_no_top_alt(Some(Expected::ParameterName), None)?; let ty = if this.eat(&token::Colon) { this.parse_ty()? } else { - this.mk_ty(this.prev_token.span, TyKind::Infer) + this.mk_ty(pat.span, TyKind::Infer) }; Ok(( @@ -2266,16 +2377,18 @@ impl<'a> Parser<'a> { let mut recover_block_from_condition = |this: &mut Self| { let block = match &mut cond.kind { ExprKind::Binary(Spanned { span: binop_span, .. }, _, right) - if let ExprKind::Block(_, None) = right.kind => { - self.sess.emit_err(errors::IfExpressionMissingThenBlock { - if_span: lo, - missing_then_block_sub: - errors::IfExpressionMissingThenBlockSub::UnfinishedCondition(cond_span.shrink_to_lo().to(*binop_span)), - let_else_sub: None, - - }); - std::mem::replace(right, this.mk_expr_err(binop_span.shrink_to_hi())) - }, + if let ExprKind::Block(_, None) = right.kind => + { + self.sess.emit_err(errors::IfExpressionMissingThenBlock { + if_span: lo, + missing_then_block_sub: + errors::IfExpressionMissingThenBlockSub::UnfinishedCondition( + cond_span.shrink_to_lo().to(*binop_span), + ), + let_else_sub: None, + }); + std::mem::replace(right, this.mk_expr_err(binop_span.shrink_to_hi())) + } ExprKind::Block(_, None) => { self.sess.emit_err(errors::IfExpressionMissingCondition { if_span: lo.shrink_to_hi(), @@ -2338,10 +2451,12 @@ impl<'a> Parser<'a> { /// Parses the condition of a `if` or `while` expression. fn parse_expr_cond(&mut self) -> PResult<'a, P<Expr>> { - let cond = + let mut cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL | Restrictions::ALLOW_LET, None)?; - if let ExprKind::Let(..) = cond.kind { + CondChecker { parser: self, forbid_let_reason: None }.visit_expr(&mut cond); + + if let ExprKind::Let(_, _, _, None) = cond.kind { // Remove the last feature gating of a `let` expression since it's stable. self.sess.gated_spans.ungate_last(sym::let_chains, cond.span); } @@ -2350,18 +2465,21 @@ impl<'a> Parser<'a> { } /// Parses a `let $pat = $expr` pseudo-expression. - fn parse_expr_let(&mut self) -> PResult<'a, P<Expr>> { - // This is a *approximate* heuristic that detects if `let` chains are - // being parsed in the right position. It's approximate because it - // doesn't deny all invalid `let` expressions, just completely wrong usages. - let not_in_chain = !matches!( - self.prev_token.kind, - TokenKind::AndAnd | TokenKind::Ident(kw::If, _) | TokenKind::Ident(kw::While, _) - ); - if !self.restrictions.contains(Restrictions::ALLOW_LET) || not_in_chain { - self.sess.emit_err(errors::ExpectedExpressionFoundLet { span: self.token.span }); - } - + fn parse_expr_let(&mut self, restrictions: Restrictions) -> PResult<'a, P<Expr>> { + let is_recovered = if !restrictions.contains(Restrictions::ALLOW_LET) { + let err = errors::ExpectedExpressionFoundLet { + span: self.token.span, + reason: ForbiddenLetReason::OtherForbidden, + }; + if self.prev_token.kind == token::BinOp(token::Or) { + // This was part of a closure, the that part of the parser recover. + return Err(err.into_diagnostic(&self.sess.span_diagnostic)); + } else { + Some(self.sess.emit_err(err)) + } + } else { + None + }; self.bump(); // Eat `let` token let lo = self.prev_token.span; let pat = self.parse_pat_allow_top_alt( @@ -2379,12 +2497,9 @@ impl<'a> Parser<'a> { } else { self.expect(&token::Eq)?; } - let expr = self.with_res(self.restrictions | Restrictions::NO_STRUCT_LITERAL, |this| { - this.parse_expr_assoc_with(1 + prec_let_scrutinee_needs_par(), None.into()) - })?; + let expr = self.parse_expr_assoc_with(1 + prec_let_scrutinee_needs_par(), None.into())?; let span = lo.to(expr.span); - self.sess.gated_spans.gate(sym::let_chains, span); - Ok(self.mk_expr(span, ExprKind::Let(pat, expr, span))) + Ok(self.mk_expr(span, ExprKind::Let(pat, expr, span, is_recovered))) } /// Parses an `else { ... }` expression (`else` token already eaten). @@ -2392,7 +2507,7 @@ impl<'a> Parser<'a> { let else_span = self.prev_token.span; // `else` let attrs = self.parse_outer_attributes()?; // For recovery. let expr = if self.eat_keyword(kw::If) { - self.parse_expr_if()? + ensure_sufficient_stack(|| self.parse_expr_if())? } else if self.check(&TokenKind::OpenDelim(Delimiter::Brace)) { self.parse_simple_block()? } else { @@ -2456,13 +2571,16 @@ impl<'a> Parser<'a> { } fn error_on_extra_if(&mut self, cond: &P<Expr>) -> PResult<'a, ()> { - if let ExprKind::Binary(Spanned { span: binop_span, node: binop}, _, right) = &cond.kind && - let BinOpKind::And = binop && - let ExprKind::If(cond, ..) = &right.kind { - Err(self.sess.create_err(errors::UnexpectedIfWithIf(binop_span.shrink_to_hi().to(cond.span.shrink_to_lo())))) - } else { - Ok(()) - } + if let ExprKind::Binary(Spanned { span: binop_span, node: binop }, _, right) = &cond.kind + && let BinOpKind::And = binop + && let ExprKind::If(cond, ..) = &right.kind + { + Err(self.sess.create_err(errors::UnexpectedIfWithIf( + binop_span.shrink_to_hi().to(cond.span.shrink_to_lo()), + ))) + } else { + Ok(()) + } } /// Parses `for <src_pat> in <src_expr> <src_loop_block>` (`for` token already eaten). @@ -2491,7 +2609,7 @@ impl<'a> Parser<'a> { // Recover from missing expression in `for` loop if matches!(expr.kind, ExprKind::Block(..)) - && !matches!(self.token.kind, token::OpenDelim(token::Delimiter::Brace)) + && !matches!(self.token.kind, token::OpenDelim(Delimiter::Brace)) && self.may_recover() { self.sess @@ -2673,7 +2791,7 @@ impl<'a> Parser<'a> { return None; } let pre_pat_snapshot = self.create_snapshot_for_diagnostic(); - match self.parse_pat_no_top_alt(None) { + match self.parse_pat_no_top_alt(None, None) { Ok(_pat) => { if self.token.kind == token::FatArrow { // Reached arm end. @@ -2733,7 +2851,10 @@ impl<'a> Parser<'a> { )?; let guard = if this.eat_keyword(kw::If) { let if_span = this.prev_token.span; - let cond = this.parse_expr_res(Restrictions::ALLOW_LET, None)?; + let mut cond = this.parse_match_guard_condition()?; + + CondChecker { parser: this, forbid_let_reason: None }.visit_expr(&mut cond); + let (has_let_expr, does_not_have_bin_op) = check_let_expr(&cond); if has_let_expr { if does_not_have_bin_op { @@ -2752,13 +2873,13 @@ impl<'a> Parser<'a> { // We might have a `=>` -> `=` or `->` typo (issue #89396). if TokenKind::FatArrow .similar_tokens() - .map_or(false, |similar_tokens| similar_tokens.contains(&this.token.kind)) + .is_some_and(|similar_tokens| similar_tokens.contains(&this.token.kind)) { err.span_suggestion( this.token.span, - "try using a fat arrow here", + "use a fat arrow to start a match arm", "=>", - Applicability::MaybeIncorrect, + Applicability::MachineApplicable, ); err.emit(); this.bump(); @@ -2807,9 +2928,9 @@ impl<'a> Parser<'a> { .or_else(|mut err| { if this.token == token::FatArrow { if let Ok(expr_lines) = sm.span_to_lines(expr.span) - && let Ok(arm_start_lines) = sm.span_to_lines(arm_start_span) - && arm_start_lines.lines[0].end_col == expr_lines.lines[0].end_col - && expr_lines.lines.len() == 2 + && let Ok(arm_start_lines) = sm.span_to_lines(arm_start_span) + && arm_start_lines.lines[0].end_col == expr_lines.lines[0].end_col + && expr_lines.lines.len() == 2 { // We check whether there's any trailing code in the parse span, // if there isn't, we very likely have the following: @@ -2875,6 +2996,37 @@ impl<'a> Parser<'a> { }) } + fn parse_match_guard_condition(&mut self) -> PResult<'a, P<Expr>> { + self.parse_expr_res(Restrictions::ALLOW_LET | Restrictions::IN_IF_GUARD, None).map_err( + |mut err| { + if self.prev_token == token::OpenDelim(Delimiter::Brace) { + let sugg_sp = self.prev_token.span.shrink_to_lo(); + // Consume everything within the braces, let's avoid further parse + // errors. + self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore); + let msg = "you might have meant to start a match arm after the match guard"; + if self.eat(&token::CloseDelim(Delimiter::Brace)) { + let applicability = if self.token.kind != token::FatArrow { + // We have high confidence that we indeed didn't have a struct + // literal in the match guard, but rather we had some operation + // that ended in a path, immediately followed by a block that was + // meant to be the match arm. + Applicability::MachineApplicable + } else { + Applicability::MaybeIncorrect + }; + err.span_suggestion_verbose(sugg_sp, msg, "=> ".to_string(), applicability); + } + } + err + }, + ) + } + + pub(crate) fn is_builtin(&self) -> bool { + self.token.is_keyword(kw::Builtin) && self.look_ahead(1, |t| *t == token::Pound) + } + /// Parses a `try {...}` expression (`try` token already eaten). fn parse_try_block(&mut self, span_lo: Span) -> PResult<'a, P<Expr>> { let (attrs, body) = self.parse_inner_attrs_and_block()?; @@ -2891,7 +3043,8 @@ impl<'a> Parser<'a> { fn is_do_catch_block(&self) -> bool { self.token.is_keyword(kw::Do) && self.is_keyword_ahead(1, &[kw::Catch]) - && self.look_ahead(2, |t| *t == token::OpenDelim(Delimiter::Brace)) + && self + .look_ahead(2, |t| *t == token::OpenDelim(Delimiter::Brace) || t.is_whole_block()) && !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL) } @@ -2901,8 +3054,9 @@ impl<'a> Parser<'a> { fn is_try_block(&self) -> bool { self.token.is_keyword(kw::Try) - && self.look_ahead(1, |t| *t == token::OpenDelim(Delimiter::Brace)) - && self.token.uninterpolated_span().rust_2018() + && self + .look_ahead(1, |t| *t == token::OpenDelim(Delimiter::Brace) || t.is_whole_block()) + && self.token.uninterpolated_span().at_least_rust_2018() } /// Parses an `async move? {...}` expression. @@ -2920,10 +3074,14 @@ impl<'a> Parser<'a> { && (( // `async move {` self.is_keyword_ahead(1, &[kw::Move]) - && self.look_ahead(2, |t| *t == token::OpenDelim(Delimiter::Brace)) + && self.look_ahead(2, |t| { + *t == token::OpenDelim(Delimiter::Brace) || t.is_whole_block() + }) ) || ( // `async {` - self.look_ahead(1, |t| *t == token::OpenDelim(Delimiter::Brace)) + self.look_ahead(1, |t| { + *t == token::OpenDelim(Delimiter::Brace) || t.is_whole_block() + }) )) } @@ -2935,9 +3093,10 @@ impl<'a> Parser<'a> { || self.look_ahead(2, |t| t == &token::Colon) && ( // `{ ident: token, ` cannot start a block. - self.look_ahead(4, |t| t == &token::Comma) || - // `{ ident: ` cannot start a block unless it's a type ascription `ident: Type`. - self.look_ahead(3, |t| !t.can_begin_type()) + self.look_ahead(4, |t| t == &token::Comma) + // `{ ident: ` cannot start a block unless it's a type ascription + // `ident: Type`. + || self.look_ahead(3, |t| !t.can_begin_type()) ) ) } @@ -2977,6 +3136,7 @@ impl<'a> Parser<'a> { let mut fields = ThinVec::new(); let mut base = ast::StructRest::None; let mut recover_async = false; + let in_if_guard = self.restrictions.contains(Restrictions::IN_IF_GUARD); let mut async_block_err = |e: &mut Diagnostic, span: Span| { recover_async = true; @@ -3013,6 +3173,31 @@ impl<'a> Parser<'a> { } else { e.span_label(pth.span, "while parsing this struct"); } + + if let Some((ident, _)) = self.token.ident() + && !self.token.is_reserved_ident() + && self.look_ahead(1, |t| { + AssocOp::from_token(&t).is_some() + || matches!(t.kind, token::OpenDelim(_)) + || t.kind == token::Dot + }) + { + // Looks like they tried to write a shorthand, complex expression. + e.span_suggestion_verbose( + self.token.span.shrink_to_lo(), + "try naming a field", + &format!("{ident}: ",), + Applicability::MaybeIncorrect, + ); + } + if in_if_guard && close_delim == Delimiter::Brace { + return Err(e); + } + + if !recover { + return Err(e); + } + e.emit(); // If the next token is a comma, then try to parse @@ -3024,11 +3209,12 @@ impl<'a> Parser<'a> { break; } } + None } }; - let is_shorthand = parsed_field.as_ref().map_or(false, |f| f.is_shorthand); + let is_shorthand = parsed_field.as_ref().is_some_and(|f| f.is_shorthand); // A shorthand field can be turned into a full field with `:`. // We should point this out. self.check_or_expected(!is_shorthand, TokenType::Token(token::Colon)); @@ -3053,19 +3239,6 @@ impl<'a> Parser<'a> { ",", Applicability::MachineApplicable, ); - } else if is_shorthand - && (AssocOp::from_token(&self.token).is_some() - || matches!(&self.token.kind, token::OpenDelim(_)) - || self.token.kind == token::Dot) - { - // Looks like they tried to write a shorthand, complex expression. - let ident = parsed_field.expect("is_shorthand implies Some").ident; - e.span_suggestion( - ident.span.shrink_to_lo(), - "try naming a field", - &format!("{ident}: "), - Applicability::HasPlaceholders, - ); } } if !recover { @@ -3151,14 +3324,10 @@ impl<'a> Parser<'a> { let label = format!("'{}", ident.name); let ident = Ident { name: Symbol::intern(&label), span: ident.span }; - self.struct_span_err(ident.span, "expected a label, found an identifier") - .span_suggestion( - ident.span, - "labels start with a tick", - label, - Applicability::MachineApplicable, - ) - .emit(); + self.sess.emit_err(errors::ExpectedLabelFoundIdent { + span: ident.span, + start: ident.span.shrink_to_lo(), + }); Label { ident } } @@ -3172,6 +3341,24 @@ impl<'a> Parser<'a> { // Check if a colon exists one ahead. This means we're parsing a fieldname. let is_shorthand = !this.look_ahead(1, |t| t == &token::Colon || t == &token::Eq); + // Proactively check whether parsing the field will be incorrect. + let is_wrong = this.token.is_ident() + && !this.token.is_reserved_ident() + && !this.look_ahead(1, |t| { + t == &token::Colon + || t == &token::Eq + || t == &token::Comma + || t == &token::CloseDelim(Delimiter::Brace) + || t == &token::CloseDelim(Delimiter::Parenthesis) + }); + if is_wrong { + return Err(errors::ExpectedStructField { + span: this.look_ahead(1, |t| t.span), + ident_span: this.token.span, + token: this.look_ahead(1, |t| t.clone()), + } + .into_diagnostic(&self.sess.span_diagnostic)); + } let (ident, expr) = if is_shorthand { // Mimic `x: x` for the `x` field shorthand. let ident = this.parse_ident_common(false)?; @@ -3246,8 +3433,8 @@ impl<'a> Parser<'a> { ExprKind::Binary(binop, lhs, rhs) } - fn mk_index(&self, expr: P<Expr>, idx: P<Expr>) -> ExprKind { - ExprKind::Index(expr, idx) + fn mk_index(&self, expr: P<Expr>, idx: P<Expr>, brackets_span: Span) -> ExprKind { + ExprKind::Index(expr, idx, brackets_span) } fn mk_call(&self, f: P<Expr>, args: ThinVec<P<Expr>>) -> ExprKind { @@ -3256,7 +3443,7 @@ impl<'a> Parser<'a> { fn mk_await_expr(&mut self, self_arg: P<Expr>, lo: Span) -> P<Expr> { let span = lo.to(self.prev_token.span); - let await_expr = self.mk_expr(span, ExprKind::Await(self_arg)); + let await_expr = self.mk_expr(span, ExprKind::Await(self_arg, self.prev_token.span)); self.recover_from_await_method_call(); await_expr } @@ -3306,3 +3493,129 @@ impl<'a> Parser<'a> { }) } } + +/// Used to forbid `let` expressions in certain syntactic locations. +#[derive(Clone, Copy, Subdiagnostic)] +pub(crate) enum ForbiddenLetReason { + /// `let` is not valid and the source environment is not important + OtherForbidden, + /// A let chain with the `||` operator + #[note(parse_not_supported_or)] + NotSupportedOr(#[primary_span] Span), + /// A let chain with invalid parentheses + /// + /// For example, `let 1 = 1 && (expr && expr)` is allowed + /// but `(let 1 = 1 && (let 1 = 1 && (let 1 = 1))) && let a = 1` is not + #[note(parse_not_supported_parentheses)] + NotSupportedParentheses(#[primary_span] Span), +} + +/// Visitor to check for invalid/unstable use of `ExprKind::Let` that can't +/// easily be caught in parsing. For example: +/// +/// ```rust,ignore (example) +/// // Only know that the let isn't allowed once the `||` token is reached +/// if let Some(x) = y || true {} +/// // Only know that the let isn't allowed once the second `=` token is reached. +/// if let Some(x) = y && z = 1 {} +/// ``` +struct CondChecker<'a> { + parser: &'a Parser<'a>, + forbid_let_reason: Option<ForbiddenLetReason>, +} + +impl MutVisitor for CondChecker<'_> { + fn visit_expr(&mut self, e: &mut P<Expr>) { + use ForbiddenLetReason::*; + + let span = e.span; + match e.kind { + ExprKind::Let(_, _, _, ref mut is_recovered @ None) => { + if let Some(reason) = self.forbid_let_reason { + *is_recovered = Some( + self.parser + .sess + .emit_err(errors::ExpectedExpressionFoundLet { span, reason }), + ); + } else { + self.parser.sess.gated_spans.gate(sym::let_chains, span); + } + } + ExprKind::Binary(Spanned { node: BinOpKind::And, .. }, _, _) => { + noop_visit_expr(e, self); + } + ExprKind::Binary(Spanned { node: BinOpKind::Or, span: or_span }, _, _) + if let None | Some(NotSupportedOr(_)) = self.forbid_let_reason => + { + let forbid_let_reason = self.forbid_let_reason; + self.forbid_let_reason = Some(NotSupportedOr(or_span)); + noop_visit_expr(e, self); + self.forbid_let_reason = forbid_let_reason; + } + ExprKind::Paren(ref inner) + if let None | Some(NotSupportedParentheses(_)) = self.forbid_let_reason => + { + let forbid_let_reason = self.forbid_let_reason; + self.forbid_let_reason = Some(NotSupportedParentheses(inner.span)); + noop_visit_expr(e, self); + self.forbid_let_reason = forbid_let_reason; + } + ExprKind::Unary(_, _) + | ExprKind::Await(_, _) + | ExprKind::Assign(_, _, _) + | ExprKind::AssignOp(_, _, _) + | ExprKind::Range(_, _, _) + | ExprKind::Try(_) + | ExprKind::AddrOf(_, _, _) + | ExprKind::Binary(_, _, _) + | ExprKind::Field(_, _) + | ExprKind::Index(_, _, _) + | ExprKind::Call(_, _) + | ExprKind::MethodCall(_) + | ExprKind::Tup(_) + | ExprKind::Paren(_) => { + let forbid_let_reason = self.forbid_let_reason; + self.forbid_let_reason = Some(OtherForbidden); + noop_visit_expr(e, self); + self.forbid_let_reason = forbid_let_reason; + } + ExprKind::Cast(ref mut op, _) | ExprKind::Type(ref mut op, _) => { + let forbid_let_reason = self.forbid_let_reason; + self.forbid_let_reason = Some(OtherForbidden); + self.visit_expr(op); + self.forbid_let_reason = forbid_let_reason; + } + ExprKind::Let(_, _, _, Some(_)) + | ExprKind::Array(_) + | ExprKind::ConstBlock(_) + | ExprKind::Lit(_) + | ExprKind::If(_, _, _) + | ExprKind::While(_, _, _) + | ExprKind::ForLoop(_, _, _, _) + | ExprKind::Loop(_, _, _) + | ExprKind::Match(_, _) + | ExprKind::Closure(_) + | ExprKind::Block(_, _) + | ExprKind::Async(_, _) + | ExprKind::TryBlock(_) + | ExprKind::Underscore + | ExprKind::Path(_, _) + | ExprKind::Break(_, _) + | ExprKind::Continue(_) + | ExprKind::Ret(_) + | ExprKind::InlineAsm(_) + | ExprKind::OffsetOf(_, _) + | ExprKind::MacCall(_) + | ExprKind::Struct(_) + | ExprKind::Repeat(_, _) + | ExprKind::Yield(_) + | ExprKind::Yeet(_) + | ExprKind::Become(_) + | ExprKind::IncludedBytes(_) + | ExprKind::FormatArgs(_) + | ExprKind::Err => { + // These would forbid any let expressions they contain already. + } + } + } +} |