| use std::borrow::Cow; | |
| use std::mem; | |
| use std::ops::Bound; | |
| use ast::Label; | |
| use rustc_ast::token::{self, Delimiter, InvisibleOrigin, MetaVarKind, TokenKind}; | |
| use rustc_ast::tokenstream::TokenTree; | |
| use rustc_ast::util::classify::{self, TrailingBrace}; | |
| use rustc_ast::visit::{Visitor, walk_expr}; | |
| use rustc_ast::{ | |
| self as ast, AttrStyle, AttrVec, Block, BlockCheckMode, DUMMY_NODE_ID, Expr, ExprKind, | |
| HasAttrs, Local, LocalKind, MacCall, MacCallStmt, MacStmtStyle, Recovered, Stmt, StmtKind, | |
| }; | |
| use rustc_errors::{Applicability, Diag, PResult}; | |
| use rustc_span::{ErrorGuaranteed, Ident, Span, kw, sym}; | |
| use thin_vec::{ThinVec, thin_vec}; | |
| use super::attr::InnerAttrForbiddenReason; | |
| use super::diagnostics::AttemptLocalParseRecovery; | |
| use super::pat::{PatternLocation, RecoverComma}; | |
| use super::path::PathStyle; | |
| use super::{ | |
| AllowConstBlockItems, AttrWrapper, BlockMode, FnContext, FnParseMode, ForceCollect, Parser, | |
| Restrictions, SemiColonMode, Trailing, UsePreAttrPos, | |
| }; | |
| use crate::diagnostics::{self, MalformedLoopLabel}; | |
| use crate::exp; | |
| impl<'a> Parser<'a> { | |
| /// Parses a statement nonterminal, which has a peculiar syntax preserved for backward | |
| /// compatibility. The parsing stops just before trailing semicolons on everything but items. | |
| /// e.g., a `StmtKind::Semi` parses to a `StmtKind::Expr`, leaving the trailing `;` unconsumed. | |
| /// | |
| /// If `force_collect` is [`ForceCollect::Yes`], forces collection of tokens regardless of | |
| /// whether or not we have attributes. | |
| // Public for rustfmt usage. | |
| pub fn parse_stmt_nonterminal(&mut self, force_collect: ForceCollect) -> Option<Stmt> { | |
| match self.parse_stmt_without_recovery(false, force_collect, false) { | |
| Ok(stmt) => Some(stmt), | |
| Err(e) => { | |
| e.emit(); | |
| self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore); | |
| None | |
| } | |
| } | |
| } | |
| /// If `force_collect` is [`ForceCollect::Yes`], forces collection of tokens regardless of | |
| /// whether or not we have attributes. If `force_full_expr` is true, parses the stmt without | |
| /// using `Restriction::STMT_EXPR`. Public for `cfg_eval` macro expansion. | |
| pub fn parse_stmt_without_recovery( | |
| &mut self, | |
| capture_semi: bool, | |
| force_collect: ForceCollect, | |
| force_full_expr: bool, | |
| ) -> PResult<'a, Stmt> { | |
| self.current_closure.take(); | |
| let pre_attr_pos = self.collect_pos(); | |
| let attrs = self.parse_outer_attributes()?; | |
| let lo = self.token.span; | |
| if let Some(mut stmt) = self.eat_metavar_seq(MetaVarKind::Stmt, |this| { | |
| this.parse_stmt_without_recovery(false, ForceCollect::Yes, false) | |
| }) { | |
| stmt.visit_attrs(|stmt_attrs| { | |
| attrs.prepend_to_nt_inner(stmt_attrs); | |
| }); | |
| return Ok(stmt); | |
| } | |
| if self.token.is_keyword(kw::Mut) && self.is_keyword_ahead(1, &[kw::Let]) { | |
| self.bump(); | |
| let mut_let_span = lo.to(self.token.span); | |
| self.dcx().emit_err(diagnostics::InvalidVariableDeclaration { | |
| span: mut_let_span, | |
| sub: diagnostics::InvalidVariableDeclarationSub::SwitchMutLetOrder(mut_let_span), | |
| }); | |
| } | |
| let stmt = if self.token.is_keyword(kw::Super) && self.is_keyword_ahead(1, &[kw::Let]) { | |
| self.collect_tokens(None, attrs, force_collect, |this, attrs| { | |
| let super_span = this.token.span; | |
| this.expect_keyword(exp!(Super))?; | |
| this.expect_keyword(exp!(Let))?; | |
| this.psess.gated_spans.gate(sym::super_let, super_span); | |
| let local = this.parse_local(Some(super_span), attrs)?; | |
| let trailing = Trailing::from(capture_semi && this.token == token::Semi); | |
| Ok(( | |
| this.mk_stmt(lo.to(this.prev_token.span), StmtKind::Let(local)), | |
| trailing, | |
| UsePreAttrPos::No, | |
| )) | |
| })? | |
| } else if self.token.is_keyword(kw::Let) { | |
| self.collect_tokens(None, attrs, force_collect, |this, attrs| { | |
| this.expect_keyword(exp!(Let))?; | |
| let local = this.parse_local(None, attrs)?; | |
| let trailing = Trailing::from(capture_semi && this.token == token::Semi); | |
| Ok(( | |
| this.mk_stmt(lo.to(this.prev_token.span), StmtKind::Let(local)), | |
| trailing, | |
| UsePreAttrPos::No, | |
| )) | |
| })? | |
| } else if self.is_kw_followed_by_ident(kw::Mut) && self.may_recover() { | |
| self.recover_stmt_local_after_let( | |
| lo, | |
| attrs, | |
| diagnostics::InvalidVariableDeclarationSub::MissingLet, | |
| force_collect, | |
| )? | |
| } else if self.is_kw_followed_by_ident(kw::Auto) && self.may_recover() { | |
| self.bump(); // `auto` | |
| self.recover_stmt_local_after_let( | |
| lo, | |
| attrs, | |
| diagnostics::InvalidVariableDeclarationSub::UseLetNotAuto, | |
| force_collect, | |
| )? | |
| } else if self.is_kw_followed_by_ident(sym::var) && self.may_recover() { | |
| self.bump(); // `var` | |
| self.recover_stmt_local_after_let( | |
| lo, | |
| attrs, | |
| diagnostics::InvalidVariableDeclarationSub::UseLetNotVar, | |
| force_collect, | |
| )? | |
| } else if self.check_path() | |
| && !self.token.is_qpath_start() | |
| && !self.is_path_start_item() | |
| && !self.is_builtin() | |
| { | |
| // We have avoided contextual keywords like `union`, items with `crate` visibility, | |
| // or `auto trait` items. We aim to parse an arbitrary path `a::b` but not something | |
| // that starts like a path (1 token), but it fact not a path. | |
| // Also, we avoid stealing syntax from `parse_item_`. | |
| // | |
| // `UsePreAttrPos::Yes` here means the attribute belongs unconditionally to the | |
| // expression, not the statement. (But the statement attributes/tokens are obtained | |
| // from the expression anyway, because `Stmt` delegates `HasAttrs`/`HasTokens` to | |
| // the things within `StmtKind`.) | |
| let stmt = self.collect_tokens( | |
| Some(pre_attr_pos), | |
| AttrWrapper::empty(), | |
| force_collect, | |
| |this, _empty_attrs| { | |
| Ok((this.parse_stmt_path_start(lo, attrs)?, Trailing::No, UsePreAttrPos::Yes)) | |
| }, | |
| ); | |
| match stmt { | |
| Ok(stmt) => stmt, | |
| Err(mut err) => { | |
| self.suggest_add_missing_let_for_stmt(&mut err); | |
| return Err(err); | |
| } | |
| } | |
| } else if let Some(item) = self.parse_item_common( | |
| attrs.clone(), // FIXME: unwanted clone of attrs | |
| false, | |
| true, | |
| FnParseMode { req_name: |_, _| true, context: FnContext::Free, req_body: true }, | |
| force_collect, | |
| AllowConstBlockItems::No, | |
| )? { | |
| self.mk_stmt(lo.to(item.span), StmtKind::Item(Box::new(item))) | |
| } else if self.eat(exp!(Semi)) { | |
| // Do not attempt to parse an expression if we're done here. | |
| self.error_outer_attrs(attrs)?; | |
| self.mk_stmt(lo, StmtKind::Empty) | |
| } else { | |
| if self.token == token::CloseBrace { | |
| self.error_outer_attrs(attrs.clone())?; | |
| } | |
| // Remainder are line-expr stmts. This is similar to the `parse_stmt_path_start` case | |
| // above. | |
| let restrictions = | |
| if force_full_expr { Restrictions::empty() } else { Restrictions::STMT_EXPR }; | |
| let e = self.collect_tokens( | |
| Some(pre_attr_pos), | |
| AttrWrapper::empty(), | |
| force_collect, | |
| |this, _empty_attrs| { | |
| let (expr, _) = this.parse_expr_res_after_attrs(restrictions, attrs)?; | |
| Ok((expr, Trailing::No, UsePreAttrPos::Yes)) | |
| }, | |
| )?; | |
| if matches!(e.kind, ExprKind::Assign(..)) && self.eat_keyword(exp!(Else)) { | |
| let bl = self.parse_block()?; | |
| // Destructuring assignment ... else. | |
| // This is not allowed, but point it out in a nice way. | |
| self.dcx() | |
| .emit_err(diagnostics::AssignmentElseNotAllowed { span: e.span.to(bl.span) }); | |
| } | |
| self.mk_stmt(lo.to(e.span), StmtKind::Expr(e)) | |
| }; | |
| self.maybe_augment_stashed_expr_in_pats_with_suggestions(&stmt); | |
| Ok(stmt) | |
| } | |
| fn parse_stmt_path_start(&mut self, lo: Span, attrs: AttrWrapper) -> PResult<'a, Stmt> { | |
| let stmt = self.collect_tokens(None, attrs, ForceCollect::No, |this, attrs| { | |
| let path = this.parse_path(PathStyle::Expr)?; | |
| if this.eat(exp!(Bang)) { | |
| let stmt_mac = this.parse_stmt_mac(lo, attrs, path)?; | |
| return Ok(( | |
| stmt_mac, | |
| Trailing::from(this.token == token::Semi), | |
| UsePreAttrPos::No, | |
| )); | |
| } | |
| let expr = if this.eat(exp!(OpenBrace)) { | |
| this.parse_expr_struct(None, path, true)? | |
| } else { | |
| let hi = this.prev_token.span; | |
| this.mk_expr(lo.to(hi), ExprKind::Path(None, path)) | |
| }; | |
| let expr = this.with_res(Restrictions::STMT_EXPR, |this| { | |
| this.parse_expr_dot_or_call_with(attrs, expr, lo) | |
| })?; | |
| // `DUMMY_SP` will get overwritten later in this function | |
| Ok(( | |
| this.mk_stmt(rustc_span::DUMMY_SP, StmtKind::Expr(expr)), | |
| Trailing::No, | |
| UsePreAttrPos::No, | |
| )) | |
| })?; | |
| if let StmtKind::Expr(expr) = stmt.kind { | |
| // Perform this outside of the `collect_tokens` closure, since our | |
| // outer attributes do not apply to this part of the expression. | |
| let (expr, _) = self.with_res(Restrictions::STMT_EXPR, |this| { | |
| this.parse_expr_assoc_rest(Bound::Unbounded, true, expr) | |
| })?; | |
| Ok(self.mk_stmt(lo.to(self.prev_token.span), StmtKind::Expr(expr))) | |
| } else { | |
| Ok(stmt) | |
| } | |
| } | |
| /// Parses a statement macro `mac!(args)` provided a `path` representing `mac`. | |
| /// At this point, the `!` token after the path has already been eaten. | |
| fn parse_stmt_mac(&mut self, lo: Span, attrs: AttrVec, path: ast::Path) -> PResult<'a, Stmt> { | |
| let args = self.parse_delim_args()?; | |
| let hi = self.prev_token.span; | |
| let style = match args.delim { | |
| Delimiter::Brace => MacStmtStyle::Braces, | |
| _ => MacStmtStyle::NoBraces, | |
| }; | |
| let mac = Box::new(MacCall { path, args }); | |
| let kind = if (style == MacStmtStyle::Braces | |
| && !matches!(self.token.kind, token::Dot | token::Question)) | |
| || matches!( | |
| self.token.kind, | |
| token::Semi | |
| | token::Eof | |
| | token::CloseInvisible(InvisibleOrigin::MetaVar(MetaVarKind::Stmt)) | |
| ) { | |
| StmtKind::MacCall(Box::new(MacCallStmt { mac, style, attrs, tokens: None })) | |
| } else { | |
| // Since none of the above applied, this is an expression statement macro. | |
| let e = self.mk_expr(lo.to(hi), ExprKind::MacCall(mac)); | |
| let e = self.maybe_recover_from_bad_qpath(e)?; | |
| let e = self.parse_expr_dot_or_call_with(attrs, e, lo)?; | |
| let (e, _) = self.parse_expr_assoc_rest(Bound::Unbounded, false, e)?; | |
| StmtKind::Expr(e) | |
| }; | |
| Ok(self.mk_stmt(lo.to(hi), kind)) | |
| } | |
| /// Error on outer attributes in this context. | |
| /// Also error if the previous token was a doc comment. | |
| fn error_outer_attrs(&self, attrs: AttrWrapper) -> PResult<'a, ()> { | |
| if attrs.is_empty() { | |
| return Ok(()); | |
| } | |
| let attrs = attrs.take_for_recovery(self.psess); | |
| let last = attrs.last().unwrap(); | |
| Err(if last.is_doc_comment() { | |
| self.dcx().create_err(diagnostics::DocCommentDoesNotDocumentAnything { | |
| span: last.span, | |
| missing_comma: None, | |
| }) | |
| } else { | |
| assert_eq!(last.style, AttrStyle::Outer); | |
| self.dcx().create_err(diagnostics::ExpectedStatementAfterOuterAttr { span: last.span }) | |
| }) | |
| } | |
| fn recover_stmt_local_after_let( | |
| &mut self, | |
| lo: Span, | |
| attrs: AttrWrapper, | |
| subdiagnostic: fn(Span) -> diagnostics::InvalidVariableDeclarationSub, | |
| force_collect: ForceCollect, | |
| ) -> PResult<'a, Stmt> { | |
| let stmt = self.collect_tokens(None, attrs, force_collect, |this, attrs| { | |
| let local = this.parse_local(None, attrs)?; | |
| // FIXME - maybe capture semicolon in recovery? | |
| Ok(( | |
| this.mk_stmt(lo.to(this.prev_token.span), StmtKind::Let(local)), | |
| Trailing::No, | |
| UsePreAttrPos::No, | |
| )) | |
| })?; | |
| self.dcx() | |
| .emit_err(diagnostics::InvalidVariableDeclaration { span: lo, sub: subdiagnostic(lo) }); | |
| Ok(stmt) | |
| } | |
| /// Parses a local variable declaration. | |
| fn parse_local(&mut self, super_: Option<Span>, attrs: AttrVec) -> PResult<'a, Box<Local>> { | |
| let lo = super_.unwrap_or(self.prev_token.span); | |
| if self.token.is_keyword(kw::Const) && self.look_ahead(1, |t| t.is_ident()) { | |
| self.dcx() | |
| .emit_err(diagnostics::ConstLetMutuallyExclusive { span: lo.to(self.token.span) }); | |
| self.bump(); | |
| } | |
| let (pat, colon) = | |
| self.parse_pat_before_ty(None, RecoverComma::Yes, PatternLocation::LetBinding)?; | |
| let (err, ty, colon_sp) = if colon { | |
| // Save the state of the parser before parsing type normally, in case there is a `:` | |
| // instead of an `=` typo. | |
| let parser_snapshot_before_type = self.clone(); | |
| let colon_sp = self.prev_token.span; | |
| match self.parse_ty() { | |
| Ok(ty) => (None, Some(ty), Some(colon_sp)), | |
| Err(mut err) => { | |
| err.span_label( | |
| colon_sp, | |
| format!( | |
| "while parsing the type for {}", | |
| pat.descr() | |
| .map_or_else(|| "the binding".to_string(), |n| format!("`{n}`")) | |
| ), | |
| ); | |
| // we use noexpect here because we don't actually expect Eq to be here | |
| // but we are still checking for it in order to be able to handle it if | |
| // it is there | |
| let err = if self.check_noexpect(&token::Eq) { | |
| err.emit(); | |
| None | |
| } else { | |
| // Rewind to before attempting to parse the type and continue parsing. | |
| let parser_snapshot_after_type = | |
| mem::replace(self, parser_snapshot_before_type); | |
| Some((parser_snapshot_after_type, colon_sp, err)) | |
| }; | |
| (err, None, Some(colon_sp)) | |
| } | |
| } | |
| } else { | |
| (None, None, None) | |
| }; | |
| let init_wrapped = self | |
| .tree_look_ahead(2, |tree| match tree { | |
| TokenTree::Token(tok, _) => tok.is_keyword(kw::Else), | |
| TokenTree::Delimited(..) => false, | |
| }) | |
| .unwrap_or(false); | |
| let init = match (self.parse_initializer(err.is_some()), err) { | |
| (Ok(init), None) => { | |
| // init parsed, ty parsed | |
| init | |
| } | |
| (Ok(init), Some((_, colon_sp, mut err))) => { | |
| // init parsed, ty error | |
| // Could parse the type as if it were the initializer, it is likely there was a | |
| // typo in the code: `:` instead of `=`. Add suggestion and emit the error. | |
| err.span_suggestion_verbose( | |
| colon_sp, | |
| "use `=` if you meant to assign", | |
| " =", | |
| Applicability::MachineApplicable, | |
| ); | |
| err.emit(); | |
| // As this was parsed successfully, continue as if the code has been fixed for the | |
| // rest of the file. It will still fail due to the emitted error, but we avoid | |
| // extra noise. | |
| init | |
| } | |
| (Err(init_err), Some((snapshot, _, ty_err))) => { | |
| // init error, ty error | |
| init_err.cancel(); | |
| // Couldn't parse the type nor the initializer, only raise the type error and | |
| // return to the parser state before parsing the type as the initializer. | |
| // let x: <parse_error>; | |
| *self = snapshot; | |
| return Err(ty_err); | |
| } | |
| (Err(err), None) => { | |
| // init error, ty parsed | |
| // Couldn't parse the initializer and we're not attempting to recover a failed | |
| // parse of the type, return the error. | |
| return Err(err); | |
| } | |
| }; | |
| let trailing_token = self.prev_token; | |
| let kind = match init { | |
| None => LocalKind::Decl, | |
| Some(init) => { | |
| if self.eat_keyword(exp!(Else)) { | |
| if self.token.is_keyword(kw::If) { | |
| // `let...else if`. Emit the same error that `parse_block()` would, | |
| // but explicitly point out that this pattern is not allowed. | |
| let msg = "conditional `else if` is not supported for `let...else`"; | |
| return Err(self.error_block_no_opening_brace_msg(Cow::from(msg))); | |
| } | |
| let els = self.parse_block()?; | |
| // These checks should also respect invisible delimiter | |
| if !init_wrapped { | |
| self.check_let_else_init_bool_expr(&init); | |
| } | |
| if matches!(trailing_token.kind, TokenKind::CloseBrace) { | |
| self.check_let_else_init_trailing_brace(&init); | |
| } | |
| LocalKind::InitElse(init, els) | |
| } else { | |
| LocalKind::Init(init) | |
| } | |
| } | |
| }; | |
| let hi = if self.token == token::Semi { self.token.span } else { self.prev_token.span }; | |
| Ok(Box::new(ast::Local { | |
| super_, | |
| ty, | |
| pat, | |
| kind, | |
| id: DUMMY_NODE_ID, | |
| span: lo.to(hi), | |
| colon_sp, | |
| attrs, | |
| tokens: None, | |
| })) | |
| } | |
| fn check_let_else_init_bool_expr(&self, init: &ast::Expr) { | |
| if let ast::ExprKind::Binary(op, ..) = init.kind { | |
| if op.node.is_lazy() { | |
| self.dcx().emit_err(diagnostics::InvalidExpressionInLetElse { | |
| span: init.span, | |
| operator: op.node.as_str(), | |
| sugg: diagnostics::WrapInParentheses::Expression { | |
| left: init.span.shrink_to_lo(), | |
| right: init.span.shrink_to_hi(), | |
| }, | |
| }); | |
| } | |
| } | |
| } | |
| fn check_let_else_init_trailing_brace(&self, init: &ast::Expr) { | |
| if let Some(trailing) = classify::expr_trailing_brace(init) { | |
| let (span, sugg) = match trailing { | |
| TrailingBrace::MacCall(mac) => ( | |
| mac.span(), | |
| diagnostics::WrapInParentheses::MacroArgs { | |
| left: mac.args.dspan.open, | |
| right: mac.args.dspan.close, | |
| }, | |
| ), | |
| TrailingBrace::Expr(expr) => ( | |
| expr.span, | |
| diagnostics::WrapInParentheses::Expression { | |
| left: expr.span.shrink_to_lo(), | |
| right: expr.span.shrink_to_hi(), | |
| }, | |
| ), | |
| }; | |
| self.dcx().emit_err(diagnostics::InvalidCurlyInLetElse { | |
| span: self.psess.source_map().end_point(span), | |
| sugg, | |
| }); | |
| } | |
| } | |
| /// Parses the RHS of a local variable declaration (e.g., `= 14;`). | |
| fn parse_initializer(&mut self, eq_optional: bool) -> PResult<'a, Option<Box<Expr>>> { | |
| let eq_consumed = match self.token.kind { | |
| token::PlusEq | |
| | token::MinusEq | |
| | token::StarEq | |
| | token::SlashEq | |
| | token::PercentEq | |
| | token::CaretEq | |
| | token::AndEq | |
| | token::OrEq | |
| | token::ShlEq | |
| | token::ShrEq => { | |
| // Recover `let x <op>= 1` as `let x = 1` We must not use `+ BytePos(1)` here | |
| // because `<op>` can be a multi-byte lookalike that was recovered, e.g. `âž–=` (the | |
| // `âž–` is a U+2796 Heavy Minus Sign Unicode Character) that was recovered as a | |
| // `-=`. | |
| let extra_op_span = self.psess.source_map().start_point(self.token.span); | |
| self.dcx().emit_err(diagnostics::CompoundAssignmentExpressionInLet { | |
| span: self.token.span, | |
| suggestion: extra_op_span, | |
| }); | |
| self.bump(); | |
| true | |
| } | |
| _ => self.eat(exp!(Eq)), | |
| }; | |
| Ok(if eq_consumed || eq_optional { Some(self.parse_expr_in_let()?) } else { None }) | |
| } | |
| /// Parses a block. No inner attributes are allowed. | |
| pub fn parse_block(&mut self) -> PResult<'a, Box<Block>> { | |
| let (attrs, block) = self.parse_inner_attrs_and_block(None)?; | |
| if let [.., last] = &*attrs { | |
| let suggest_to_outer = match &last.kind { | |
| ast::AttrKind::Normal(attr) => attr.item.is_valid_for_outer_style(), | |
| _ => false, | |
| }; | |
| self.error_on_forbidden_inner_attr( | |
| last.span, | |
| super::attr::InnerAttrPolicy::Forbidden(Some( | |
| InnerAttrForbiddenReason::InCodeBlock, | |
| )), | |
| suggest_to_outer, | |
| ); | |
| } | |
| Ok(block) | |
| } | |
| fn error_block_no_opening_brace_msg(&mut self, msg: Cow<'static, str>) -> Diag<'a> { | |
| let prev = self.prev_token.span; | |
| let sp = self.token.span; | |
| let mut err = self.dcx().struct_span_err(sp, msg); | |
| self.label_expected_raw_ref(&mut err); | |
| err.span_label(sp, "expected `{`"); | |
| if self.token == token::CloseBrace { | |
| return err; | |
| } | |
| let do_not_suggest_help = self.token.is_keyword(kw::In) | |
| || self.token == token::Colon | |
| || self.prev_token.is_keyword(kw::Raw); | |
| // Check to see if the user has written something like | |
| // | |
| // if (cond) | |
| // bar; | |
| // | |
| // which is valid in other languages, but not Rust. | |
| match self.parse_stmt_without_recovery(false, ForceCollect::No, false) { | |
| // If the next token is an open brace, e.g., we have: | |
| // | |
| // if expr other_expr { | |
| // ^ ^ ^- lookahead(1) is a brace | |
| // | |- current token is not "else" | |
| // |- (statement we just parsed) | |
| // | |
| // the place-inside-a-block suggestion would be more likely wrong than right. | |
| // | |
| // FIXME(compiler-errors): this should probably parse an arbitrary expr and not | |
| // just lookahead one token, so we can see if there's a brace after _that_, | |
| // since we want to protect against: | |
| // `if 1 1 + 1 {` being suggested as `if { 1 } 1 + 1 {` | |
| // + + | |
| Ok(_) | |
| if (!self.token.is_keyword(kw::Else) | |
| && self.look_ahead(1, |t| t == &token::OpenBrace)) | |
| || do_not_suggest_help => {} | |
| // Do not suggest `if foo println!("") {;}` (as would be seen in test for #46836). | |
| Ok(Stmt { kind: StmtKind::Empty, .. }) => {} | |
| Ok(stmt) => { | |
| let stmt_own_line = self.psess.source_map().is_line_before_span_empty(sp); | |
| let stmt_span = if stmt_own_line && self.eat(exp!(Semi)) { | |
| // Expand the span to include the semicolon. | |
| stmt.span.with_hi(self.prev_token.span.hi()) | |
| } else { | |
| stmt.span | |
| }; | |
| self.suggest_fixes_misparsed_for_loop_head( | |
| &mut err, | |
| prev.between(sp), | |
| stmt_span, | |
| &stmt.kind, | |
| ); | |
| } | |
| Err(e) => { | |
| e.delay_as_bug(); | |
| } | |
| } | |
| err | |
| } | |
| fn suggest_fixes_misparsed_for_loop_head( | |
| &self, | |
| e: &mut Diag<'_>, | |
| between: Span, | |
| stmt_span: Span, | |
| stmt_kind: &StmtKind, | |
| ) { | |
| match (&self.token.kind, &stmt_kind) { | |
| (token::OpenBrace, StmtKind::Expr(expr)) if let ExprKind::Call(..) = expr.kind => { | |
| // for _ in x y() {} | |
| e.span_suggestion_verbose( | |
| between, | |
| "you might have meant to write a method call", | |
| ".".to_string(), | |
| Applicability::MaybeIncorrect, | |
| ); | |
| } | |
| (token::OpenBrace, StmtKind::Expr(expr)) if let ExprKind::Field(..) = expr.kind => { | |
| // for _ in x y.z {} | |
| e.span_suggestion_verbose( | |
| between, | |
| "you might have meant to write a field access", | |
| ".".to_string(), | |
| Applicability::MaybeIncorrect, | |
| ); | |
| } | |
| (token::CloseBrace, StmtKind::Expr(expr)) | |
| if let ExprKind::Struct(expr) = &expr.kind | |
| && let None = expr.qself | |
| && expr.path.segments.len() == 1 => | |
| { | |
| // This is specific to "mistyped `if` condition followed by empty body" | |
| // | |
| // for _ in x y {} | |
| e.span_suggestion_verbose( | |
| between, | |
| "you might have meant to write a field access", | |
| ".".to_string(), | |
| Applicability::MaybeIncorrect, | |
| ); | |
| } | |
| (token::OpenBrace, StmtKind::Expr(expr)) | |
| if let ExprKind::Lit(lit) = expr.kind | |
| && let None = lit.suffix | |
| && let token::LitKind::Integer | token::LitKind::Float = lit.kind => | |
| { | |
| // for _ in x 0 {} | |
| // for _ in x 0.0 {} | |
| e.span_suggestion_verbose( | |
| between, | |
| format!("you might have meant to write a field access"), | |
| ".".to_string(), | |
| Applicability::MaybeIncorrect, | |
| ); | |
| } | |
| (token::OpenBrace, StmtKind::Expr(expr)) | |
| if let ExprKind::Loop(..) | |
| | ExprKind::If(..) | |
| | ExprKind::While(..) | |
| | ExprKind::Match(..) | |
| | ExprKind::ForLoop { .. } | |
| | ExprKind::TryBlock(..) | |
| | ExprKind::Ret(..) | |
| | ExprKind::Closure(..) | |
| | ExprKind::Struct(..) | |
| | ExprKind::Try(..) = expr.kind => | |
| { | |
| // These are more likely to have been meant as a block body. | |
| e.multipart_suggestion( | |
| "you might have meant to write this as part of a block", | |
| vec![ | |
| (stmt_span.shrink_to_lo(), "{ ".to_string()), | |
| (stmt_span.shrink_to_hi(), " }".to_string()), | |
| ], | |
| // Speculative; has been misleading in the past (#46836). | |
| Applicability::MaybeIncorrect, | |
| ); | |
| } | |
| (token::OpenBrace, _) => {} | |
| (_, _) => { | |
| e.multipart_suggestion( | |
| "you might have meant to write this as part of a block", | |
| vec![ | |
| (stmt_span.shrink_to_lo(), "{ ".to_string()), | |
| (stmt_span.shrink_to_hi(), " }".to_string()), | |
| ], | |
| // Speculative; has been misleading in the past (#46836). | |
| Applicability::MaybeIncorrect, | |
| ); | |
| } | |
| } | |
| } | |
| fn error_block_no_opening_brace<T>(&mut self) -> PResult<'a, T> { | |
| let tok = super::token_descr(&self.token); | |
| let msg = format!("expected `{{`, found {tok}"); | |
| Err(self.error_block_no_opening_brace_msg(Cow::from(msg))) | |
| } | |
| /// Parses a block. Inner attributes are allowed, block labels are not. | |
| /// | |
| /// If `loop_header` is `Some` and an unexpected block label is encountered, | |
| /// it is suggested to be moved just before `loop_header`, else it is suggested to be removed. | |
| pub(super) fn parse_inner_attrs_and_block( | |
| &mut self, | |
| loop_header: Option<Span>, | |
| ) -> PResult<'a, (AttrVec, Box<Block>)> { | |
| self.parse_block_common(self.token.span, BlockCheckMode::Default, loop_header) | |
| } | |
| /// Parses a block. Inner attributes are allowed, block labels are not. | |
| /// | |
| /// If `loop_header` is `Some` and an unexpected block label is encountered, | |
| /// it is suggested to be moved just before `loop_header`, else it is suggested to be removed. | |
| pub(super) fn parse_block_common( | |
| &mut self, | |
| lo: Span, | |
| blk_mode: BlockCheckMode, | |
| loop_header: Option<Span>, | |
| ) -> PResult<'a, (AttrVec, Box<Block>)> { | |
| if let Some(block) = self.eat_metavar_seq(MetaVarKind::Block, |this| this.parse_block()) { | |
| return Ok((AttrVec::new(), block)); | |
| } | |
| let maybe_ident = self.prev_token; | |
| self.maybe_recover_unexpected_block_label(loop_header); | |
| if !self.eat(exp!(OpenBrace)) { | |
| return self.error_block_no_opening_brace(); | |
| } | |
| let attrs = self.parse_inner_attributes()?; | |
| let tail = match self.maybe_suggest_struct_literal(lo, blk_mode, maybe_ident) { | |
| Some(tail) => tail?, | |
| None => self.parse_block_tail(lo, blk_mode, AttemptLocalParseRecovery::Yes)?, | |
| }; | |
| Ok((attrs, tail)) | |
| } | |
| /// Parses the rest of a block expression or function body. | |
| /// Precondition: already parsed the '{'. | |
| pub fn parse_block_tail( | |
| &mut self, | |
| lo: Span, | |
| s: BlockCheckMode, | |
| recover: AttemptLocalParseRecovery, | |
| ) -> PResult<'a, Box<Block>> { | |
| let mut stmts = ThinVec::new(); | |
| let mut snapshot = None; | |
| while !self.eat(exp!(CloseBrace)) { | |
| if self.token == token::Eof { | |
| break; | |
| } | |
| if self.is_vcs_conflict_marker(&TokenKind::Shl, &TokenKind::Lt) { | |
| // Account for `<<<<<<<` diff markers. We can't proactively error here because | |
| // that can be a valid path start, so we snapshot and reparse only we've | |
| // encountered another parse error. | |
| snapshot = Some(self.create_snapshot_for_diagnostic()); | |
| } | |
| let stmt = match self.parse_full_stmt(recover) { | |
| Err(mut err) if recover.yes() => { | |
| if let Some(ref mut snapshot) = snapshot { | |
| snapshot.recover_vcs_conflict_marker(); | |
| } | |
| if self.token == token::Colon { | |
| // if a previous and next token of the current one is | |
| // integer literal (e.g. `1:42`), it's likely a range | |
| // expression for Pythonistas and we can suggest so. | |
| if self.prev_token.is_integer_lit() | |
| && self.may_recover() | |
| && self.look_ahead(1, |token| token.is_integer_lit()) | |
| { | |
| // FIXME(hkmatsumoto): Might be better to trigger | |
| // this only when parsing an index expression. | |
| err.span_suggestion_verbose( | |
| self.token.span, | |
| "you might have meant a range expression", | |
| "..", | |
| Applicability::MaybeIncorrect, | |
| ); | |
| } else { | |
| // if next token is following a colon, it's likely a path | |
| // and we can suggest a path separator | |
| self.bump(); | |
| if self.token.span.lo() == self.prev_token.span.hi() { | |
| err.span_suggestion_verbose( | |
| self.prev_token.span, | |
| "maybe write a path separator here", | |
| "::", | |
| Applicability::MaybeIncorrect, | |
| ); | |
| } | |
| } | |
| } | |
| let guar = err.emit_err(); | |
| self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore); | |
| self.mk_stmt_err(self.token.span, guar) | |
| } | |
| Ok(stmt) => stmt, | |
| Err(err) => return Err(err), | |
| }; | |
| stmts.push(stmt); | |
| } | |
| Ok(self.mk_block(stmts, s, lo.to(self.prev_token.span))) | |
| } | |
| fn recover_missing_let_else(&mut self, err: &mut Diag<'_>, pat: &ast::Pat, stmt_span: Span) { | |
| if self.token.kind != token::OpenBrace { | |
| return; | |
| } | |
| match pat.kind { | |
| ast::PatKind::Ident(..) | ast::PatKind::Missing | ast::PatKind::Wild => { | |
| // Not if let or let else | |
| return; | |
| } | |
| _ => {} | |
| } | |
| let snapshot = self.create_snapshot_for_diagnostic(); | |
| let block_span = self.token.span; | |
| let (if_let, let_else) = match self.parse_block() { | |
| Ok(block) => { | |
| let mut idents = vec![]; | |
| pat.walk(&mut |pat: &ast::Pat| { | |
| if let ast::PatKind::Ident(_, ident, _) = pat.kind { | |
| idents.push(ident); | |
| } | |
| true | |
| }); | |
| struct IdentFinder { | |
| idents: Vec<Ident>, | |
| /// If a block references one of the bindings introduced by the let pattern, | |
| /// we likely meant to use `if let`. | |
| /// This is pre-expansion, so if we encounter | |
| /// `let Some(x) = foo() { println!("{x}") }` we won't find it. | |
| references_ident: bool = false, | |
| /// If a block has a `return`, then we know with high certainty that it was | |
| /// meant to be let-else. | |
| has_return: bool = false, | |
| } | |
| impl<'a> Visitor<'a> for IdentFinder { | |
| fn visit_ident(&mut self, ident: &Ident) { | |
| for i in &self.idents { | |
| if ident.name == i.name { | |
| self.references_ident = true; | |
| } | |
| } | |
| } | |
| fn visit_expr(&mut self, node: &'a Expr) { | |
| if let ExprKind::Ret(..) = node.kind { | |
| self.has_return = true; | |
| } | |
| walk_expr(self, node); | |
| } | |
| } | |
| // Collect all bindings in pattern and see if they appear in the block. Likely meant | |
| // to write `if let`. See if the block has a return. Likely meant to write | |
| // `let else`. | |
| let mut visitor = IdentFinder { idents, .. }; | |
| visitor.visit_block(&block); | |
| (visitor.references_ident, visitor.has_return) | |
| } | |
| Err(e) => { | |
| e.cancel(); | |
| self.restore_snapshot(snapshot); | |
| (false, false) | |
| } | |
| }; | |
| let mut alternatively = ""; | |
| if if_let || !let_else { | |
| alternatively = "alternatively, "; | |
| err.span_suggestion_verbose( | |
| stmt_span.shrink_to_lo(), | |
| "you might have meant to use `if let`", | |
| "if ".to_string(), | |
| if if_let { | |
| Applicability::MachineApplicable | |
| } else { | |
| Applicability::MaybeIncorrect | |
| }, | |
| ); | |
| } | |
| if let_else || !if_let { | |
| err.span_suggestion_verbose( | |
| block_span.shrink_to_lo(), | |
| format!("{alternatively}you might have meant to use `let...else`"), | |
| "else ".to_string(), | |
| if let_else { | |
| Applicability::MachineApplicable | |
| } else { | |
| Applicability::MaybeIncorrect | |
| }, | |
| ); | |
| } | |
| } | |
| fn recover_missing_dot(&mut self, err: &mut Diag<'_>) { | |
| let Some((ident, _)) = self.token.ident() else { | |
| return; | |
| }; | |
| if let Some(c) = ident.name.as_str().chars().next() | |
| && c.is_uppercase() | |
| { | |
| return; | |
| } | |
| if self.token.is_reserved_ident() && !self.token.is_ident_named(kw::Await) { | |
| return; | |
| } | |
| if self.prev_token.is_reserved_ident() && self.prev_token.is_ident_named(kw::Await) { | |
| // Likely `foo.await bar` | |
| } else if self.prev_token.is_non_reserved_ident() { | |
| // Likely `foo bar` | |
| } else if self.prev_token.kind == token::Question { | |
| // `foo? bar` | |
| } else if self.prev_token.kind == token::CloseParen { | |
| // `foo() bar` | |
| } else { | |
| return; | |
| } | |
| if self.token.span == self.prev_token.span { | |
| // Account for syntax errors in proc-macros. | |
| return; | |
| } | |
| if self.look_ahead(1, |t| [token::Semi, token::Question, token::Dot].contains(&t.kind)) { | |
| err.span_suggestion_verbose( | |
| self.prev_token.span.between(self.token.span), | |
| "you might have meant to write a field access", | |
| ".".to_string(), | |
| Applicability::MaybeIncorrect, | |
| ); | |
| } | |
| if self.look_ahead(1, |t| t.kind == token::OpenParen) { | |
| err.span_suggestion_verbose( | |
| self.prev_token.span.between(self.token.span), | |
| "you might have meant to write a method call", | |
| ".".to_string(), | |
| Applicability::MaybeIncorrect, | |
| ); | |
| } | |
| } | |
| fn try_recover_let_missing_semi(&mut self, local: &mut Local) -> Option<ErrorGuaranteed> { | |
| let expr = match &mut local.kind { | |
| LocalKind::Init(expr) | LocalKind::InitElse(expr, _) => expr, | |
| LocalKind::Decl => return None, | |
| }; | |
| if let Some((span, guar)) = | |
| self.missing_semi_from_binop("`let` binding", expr, Some(local.span.shrink_to_lo())) | |
| { | |
| self.fn_body_missing_semi_guar = Some(guar); | |
| *expr = self.mk_expr(span, ExprKind::Err(guar)); | |
| return Some(guar); | |
| } | |
| None | |
| } | |
| /// Parses a statement, including the trailing semicolon. | |
| pub fn parse_full_stmt(&mut self, recover: AttemptLocalParseRecovery) -> PResult<'a, Stmt> { | |
| // Skip looking for a trailing semicolon when we have a metavar seq. | |
| if let Some(stmt) = self.eat_metavar_seq(MetaVarKind::Stmt, |this| { | |
| // Why pass `true` for `force_full_expr`? Statement expressions are less expressive | |
| // than "full" expressions, due to the `STMT_EXPR` restriction, and sometimes need | |
| // parentheses. E.g. the "full" expression `match paren_around_match {} | true` when | |
| // used in statement context must be written `(match paren_around_match {} | true)`. | |
| // However, if the expression we are parsing in this statement context was pasted by a | |
| // declarative macro, it may have come from a "full" expression context, and lack | |
| // these parentheses. So we lift the `STMT_EXPR` restriction to ensure the statement | |
| // will reparse successfully. | |
| this.parse_stmt_without_recovery(false, ForceCollect::No, true) | |
| }) { | |
| return Ok(stmt); | |
| } | |
| let mut stmt = self.parse_stmt_without_recovery(true, ForceCollect::No, false)?; | |
| let mut eat_semi = true; | |
| let mut add_semi_to_stmt = false; | |
| match &mut stmt.kind { | |
| // Expression without semicolon. | |
| StmtKind::Expr(expr) | |
| if classify::expr_requires_semi_to_be_stmt(expr) | |
| && !expr.attrs.is_empty() | |
| && !matches!(self.token.kind, token::Eof | token::Semi | token::CloseBrace) => | |
| { | |
| // The user has written `#[attr] expr` which is unsupported. (#106020) | |
| let guar = self.attr_on_non_tail_expr(&expr); | |
| // We already emitted an error, so don't emit another type error | |
| let sp = expr.span.to(self.prev_token.span); | |
| *expr = self.mk_expr_err(sp, guar); | |
| } | |
| // Expression without semicolon. | |
| StmtKind::Expr(expr) | |
| if self.token != token::Eof && classify::expr_requires_semi_to_be_stmt(expr) => | |
| { | |
| // Just check for errors and recover; do not eat semicolon yet. | |
| let expect_result = | |
| if let Err(e) = self.maybe_recover_from_ternary_operator(Some(expr.span)) { | |
| Err(e) | |
| } else { | |
| self.expect_one_of(&[], &[exp!(Semi), exp!(CloseBrace)]) | |
| }; | |
| // Try to both emit a better diagnostic, and avoid further errors by replacing | |
| // the `expr` with `ExprKind::Err`. | |
| let replace_with_err = 'break_recover: { | |
| match expect_result { | |
| Ok(Recovered::No) => None, | |
| Ok(Recovered::Yes(guar)) => { | |
| // Skip type error to avoid extra errors. | |
| Some(guar) | |
| } | |
| Err(e) => { | |
| if self.recover_colon_as_semi() { | |
| // recover_colon_as_semi has already emitted a nicer error. | |
| e.delay_as_bug(); | |
| add_semi_to_stmt = true; | |
| eat_semi = false; | |
| break 'break_recover None; | |
| } | |
| if self.token == token::Colon | |
| && let ExprKind::Path(None, ast::Path { segments, .. }) = &expr.kind | |
| && let [segment] = segments.as_slice() | |
| && self.look_ahead(1, |t| { | |
| t.is_metavar_block() | |
| || t.kind == token::OpenBrace | |
| || t.non_raw_ident().is_some_and(|ident| { | |
| matches!(ident.name, kw::For | kw::Loop | kw::While) | |
| }) | |
| }) | |
| { | |
| let snapshot = self.create_snapshot_for_diagnostic(); | |
| let label = Label { | |
| ident: Ident::from_str_and_span( | |
| &format!("'{}", segment.ident), | |
| segment.ident.span, | |
| ), | |
| }; | |
| match self.parse_expr_labeled(label, false) { | |
| Ok(labeled_expr) => { | |
| e.cancel(); | |
| self.dcx().emit_err(MalformedLoopLabel { | |
| span: label.ident.span, | |
| suggestion: label.ident.span.shrink_to_lo(), | |
| }); | |
| *expr = labeled_expr; | |
| break 'break_recover None; | |
| } | |
| Err(err) => { | |
| err.cancel(); | |
| self.restore_snapshot(snapshot); | |
| } | |
| } | |
| } | |
| let res = | |
| self.check_mistyped_turbofish_with_multiple_type_params(e, expr); | |
| Some(if recover.no() { | |
| res? | |
| } else { | |
| res.unwrap_or_else(|mut e| { | |
| self.recover_missing_dot(&mut e); | |
| let guar = e.emit_err(); | |
| self.recover_stmt(); | |
| guar | |
| }) | |
| }) | |
| } | |
| } | |
| }; | |
| if let Some(guar) = replace_with_err { | |
| // We already emitted an error, so don't emit another type error | |
| let sp = expr.span.to(self.prev_token.span); | |
| *expr = self.mk_expr_err(sp, guar); | |
| } | |
| } | |
| StmtKind::Expr(_) | StmtKind::MacCall(_) => {} | |
| StmtKind::Let(local) => { | |
| if self.try_recover_let_missing_semi(local).is_some() { | |
| return Ok(stmt); | |
| } | |
| if let Err(mut e) = self.expect_semi() { | |
| // We might be at the `,` in `let x = foo<bar, baz>;`. Try to recover. | |
| match &mut local.kind { | |
| LocalKind::Init(expr) | LocalKind::InitElse(expr, _) => { | |
| self.check_mistyped_turbofish_with_multiple_type_params(e, expr) | |
| .map_err(|mut e| { | |
| self.recover_missing_dot(&mut e); | |
| self.recover_missing_let_else(&mut e, &local.pat, stmt.span); | |
| e | |
| })?; | |
| // We found `foo<bar, baz>`, have we fully recovered? | |
| self.expect_semi()?; | |
| } | |
| LocalKind::Decl => { | |
| if let Some(colon_sp) = local.colon_sp { | |
| e.span_label( | |
| colon_sp, | |
| format!( | |
| "while parsing the type for {}", | |
| local.pat.descr().map_or_else( | |
| || "the binding".to_string(), | |
| |n| format!("`{n}`") | |
| ) | |
| ), | |
| ); | |
| let suggest_eq = if self.token == token::Dot | |
| && let _ = self.bump() | |
| && let mut snapshot = self.create_snapshot_for_diagnostic() | |
| && let Ok(_) = snapshot | |
| .parse_dot_suffix_expr( | |
| colon_sp, | |
| self.mk_expr_err( | |
| colon_sp, | |
| self.dcx().delayed_bug( | |
| "error during `:` -> `=` recovery", | |
| ), | |
| ), | |
| ) | |
| .map_err(Diag::cancel) | |
| { | |
| true | |
| } else if let Some(op) = self.check_assoc_op() | |
| && super::expr::diagnostics::op_can_continue_stmt_expr_unambiguously(op.node) | |
| { | |
| true | |
| } else { | |
| false | |
| }; | |
| if suggest_eq && let Some(ty) = &local.ty { | |
| e.span_suggestion_verbose( | |
| local.pat.span.between(ty.span), | |
| "use `=` if you meant to assign", | |
| " = ", | |
| Applicability::MaybeIncorrect, | |
| ); | |
| } | |
| } | |
| return Err(e); | |
| } | |
| } | |
| } | |
| eat_semi = false; | |
| } | |
| StmtKind::Empty | StmtKind::Item(_) | StmtKind::Semi(_) => eat_semi = false, | |
| } | |
| if add_semi_to_stmt || (eat_semi && self.eat(exp!(Semi))) { | |
| stmt = stmt.add_trailing_semicolon(); | |
| } | |
| stmt.span = stmt.span.to(self.prev_token.span); | |
| Ok(stmt) | |
| } | |
| pub(super) fn mk_block( | |
| &self, | |
| stmts: ThinVec<Stmt>, | |
| rules: BlockCheckMode, | |
| span: Span, | |
| ) -> Box<Block> { | |
| Box::new(Block { stmts, id: DUMMY_NODE_ID, rules, span }) | |
| } | |
| pub(super) fn mk_stmt(&self, span: Span, kind: StmtKind) -> Stmt { | |
| Stmt { id: DUMMY_NODE_ID, kind, span } | |
| } | |
| pub(super) fn mk_stmt_err(&self, span: Span, guar: ErrorGuaranteed) -> Stmt { | |
| self.mk_stmt(span, StmtKind::Expr(self.mk_expr_err(span, guar))) | |
| } | |
| pub(super) fn mk_block_err(&self, span: Span, guar: ErrorGuaranteed) -> Box<Block> { | |
| self.mk_block(thin_vec![self.mk_stmt_err(span, guar)], BlockCheckMode::Default, span) | |
| } | |
| } |