From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:02:58 +0200 Subject: Adding upstream version 1.64.0+dfsg1. Signed-off-by: Daniel Baumann --- compiler/rustc_parse/src/parser/stmt.rs | 648 ++++++++++++++++++++++++++++++++ 1 file changed, 648 insertions(+) create mode 100644 compiler/rustc_parse/src/parser/stmt.rs (limited to 'compiler/rustc_parse/src/parser/stmt.rs') diff --git a/compiler/rustc_parse/src/parser/stmt.rs b/compiler/rustc_parse/src/parser/stmt.rs new file mode 100644 index 000000000..51bd9d2d3 --- /dev/null +++ b/compiler/rustc_parse/src/parser/stmt.rs @@ -0,0 +1,648 @@ +use super::attr::DEFAULT_INNER_ATTR_FORBIDDEN; +use super::diagnostics::{AttemptLocalParseRecovery, Error}; +use super::expr::LhsExpr; +use super::pat::RecoverComma; +use super::path::PathStyle; +use super::TrailingToken; +use super::{ + AttrWrapper, BlockMode, FnParseMode, ForceCollect, Parser, Restrictions, SemiColonMode, +}; +use crate::maybe_whole; + +use rustc_ast as ast; +use rustc_ast::ptr::P; +use rustc_ast::token::{self, Delimiter, TokenKind}; +use rustc_ast::util::classify; +use rustc_ast::{AttrStyle, AttrVec, Attribute, LocalKind, MacCall, MacCallStmt, MacStmtStyle}; +use rustc_ast::{Block, BlockCheckMode, Expr, ExprKind, HasAttrs, Local, Stmt}; +use rustc_ast::{StmtKind, DUMMY_NODE_ID}; +use rustc_errors::{Applicability, DiagnosticBuilder, ErrorGuaranteed, PResult}; +use rustc_span::source_map::{BytePos, Span}; +use rustc_span::symbol::{kw, sym}; + +use std::mem; + +impl<'a> Parser<'a> { + /// Parses a statement. This stops just before trailing semicolons on everything but items. + /// e.g., a `StmtKind::Semi` parses to a `StmtKind::Expr`, leaving the trailing `;` unconsumed. + // Public for rustfmt usage. + pub fn parse_stmt(&mut self, force_collect: ForceCollect) -> PResult<'a, Option> { + Ok(self.parse_stmt_without_recovery(false, force_collect).unwrap_or_else(|mut e| { + e.emit(); + self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore); + None + })) + } + + /// If `force_capture` is true, forces collection of tokens regardless of whether + /// or not we have attributes + pub(crate) fn parse_stmt_without_recovery( + &mut self, + capture_semi: bool, + force_collect: ForceCollect, + ) -> PResult<'a, Option> { + let attrs = self.parse_outer_attributes()?; + let lo = self.token.span; + + // Don't use `maybe_whole` so that we have precise control + // over when we bump the parser + if let token::Interpolated(nt) = &self.token.kind && let token::NtStmt(stmt) = &**nt { + let mut stmt = stmt.clone(); + self.bump(); + stmt.visit_attrs(|stmt_attrs| { + attrs.prepend_to_nt_inner(stmt_attrs); + }); + return Ok(Some(stmt.into_inner())); + } + + Ok(Some(if self.token.is_keyword(kw::Let) { + self.parse_local_mk(lo, attrs, capture_semi, force_collect)? + } else if self.is_kw_followed_by_ident(kw::Mut) { + self.recover_stmt_local(lo, attrs, "missing keyword", "let mut")? + } else if self.is_kw_followed_by_ident(kw::Auto) { + self.bump(); // `auto` + let msg = "write `let` instead of `auto` to introduce a new variable"; + self.recover_stmt_local(lo, attrs, msg, "let")? + } else if self.is_kw_followed_by_ident(sym::var) { + self.bump(); // `var` + let msg = "write `let` instead of `var` to introduce a new variable"; + self.recover_stmt_local(lo, attrs, msg, "let")? + } else if self.check_path() && !self.token.is_qpath_start() && !self.is_path_start_item() { + // 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_`. + if force_collect == ForceCollect::Yes { + self.collect_tokens_no_attrs(|this| this.parse_stmt_path_start(lo, attrs)) + } else { + self.parse_stmt_path_start(lo, attrs) + }? + } else if let Some(item) = self.parse_item_common( + attrs.clone(), + false, + true, + FnParseMode { req_name: |_| true, req_body: true }, + force_collect, + )? { + // FIXME: Bad copy of attrs + self.mk_stmt(lo.to(item.span), StmtKind::Item(P(item))) + } else if self.eat(&token::Semi) { + // Do not attempt to parse an expression if we're done here. + self.error_outer_attrs(&attrs.take_for_recovery()); + self.mk_stmt(lo, StmtKind::Empty) + } else if self.token != token::CloseDelim(Delimiter::Brace) { + // Remainder are line-expr stmts. + let e = if force_collect == ForceCollect::Yes { + self.collect_tokens_no_attrs(|this| { + this.parse_expr_res(Restrictions::STMT_EXPR, Some(attrs)) + }) + } else { + self.parse_expr_res(Restrictions::STMT_EXPR, Some(attrs)) + }?; + if matches!(e.kind, ExprKind::Assign(..)) && self.eat_keyword(kw::Else) { + let bl = self.parse_block()?; + // Destructuring assignment ... else. + // This is not allowed, but point it out in a nice way. + let mut err = self.struct_span_err( + e.span.to(bl.span), + " ... else { ... } is not allowed", + ); + err.emit(); + } + self.mk_stmt(lo.to(e.span), StmtKind::Expr(e)) + } else { + self.error_outer_attrs(&attrs.take_for_recovery()); + return Ok(None); + })) + } + + fn parse_stmt_path_start(&mut self, lo: Span, attrs: AttrWrapper) -> PResult<'a, Stmt> { + let stmt = self.collect_tokens_trailing_token(attrs, ForceCollect::No, |this, attrs| { + let path = this.parse_path(PathStyle::Expr)?; + + if this.eat(&token::Not) { + let stmt_mac = this.parse_stmt_mac(lo, attrs.into(), path)?; + if this.token == token::Semi { + return Ok((stmt_mac, TrailingToken::Semi)); + } else { + return Ok((stmt_mac, TrailingToken::None)); + } + } + + let expr = if this.eat(&token::OpenDelim(Delimiter::Brace)) { + this.parse_struct_expr(None, path, AttrVec::new(), true)? + } else { + let hi = this.prev_token.span; + this.mk_expr(lo.to(hi), ExprKind::Path(None, path), AttrVec::new()) + }; + + let expr = this.with_res(Restrictions::STMT_EXPR, |this| { + this.parse_dot_or_call_expr_with(expr, lo, attrs) + })?; + // `DUMMY_SP` will get overwritten later in this function + Ok((this.mk_stmt(rustc_span::DUMMY_SP, StmtKind::Expr(expr)), TrailingToken::None)) + })?; + + if let StmtKind::Expr(expr) = stmt.kind { + // Perform this outside of the `collect_tokens_trailing_token` 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_assoc_expr_with(0, LhsExpr::AlreadyParsed(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_mac_args()?; + let delim = args.delim(); + let hi = self.prev_token.span; + + let style = match delim { + Some(Delimiter::Brace) => MacStmtStyle::Braces, + Some(_) => MacStmtStyle::NoBraces, + None => unreachable!(), + }; + + let mac = MacCall { path, args, prior_type_ascription: self.last_type_ascription }; + + let kind = if (style == MacStmtStyle::Braces + && self.token != token::Dot + && self.token != token::Question) + || self.token == token::Semi + || self.token == token::Eof + { + StmtKind::MacCall(P(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), AttrVec::new()); + let e = self.maybe_recover_from_bad_qpath(e)?; + let e = self.parse_dot_or_call_expr_with(e, lo, attrs.into())?; + let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(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: &[Attribute]) { + if let [.., last] = attrs { + if last.is_doc_comment() { + self.span_err(last.span, Error::UselessDocComment).emit(); + } else if attrs.iter().any(|a| a.style == AttrStyle::Outer) { + self.struct_span_err(last.span, "expected statement after outer attribute").emit(); + } + } + } + + fn recover_stmt_local( + &mut self, + lo: Span, + attrs: AttrWrapper, + msg: &str, + sugg: &str, + ) -> PResult<'a, Stmt> { + let stmt = self.recover_local_after_let(lo, attrs)?; + self.struct_span_err(lo, "invalid variable declaration") + .span_suggestion(lo, msg, sugg, Applicability::MachineApplicable) + .emit(); + Ok(stmt) + } + + fn parse_local_mk( + &mut self, + lo: Span, + attrs: AttrWrapper, + capture_semi: bool, + force_collect: ForceCollect, + ) -> PResult<'a, Stmt> { + self.collect_tokens_trailing_token(attrs, force_collect, |this, attrs| { + this.expect_keyword(kw::Let)?; + let local = this.parse_local(attrs.into())?; + let trailing = if capture_semi && this.token.kind == token::Semi { + TrailingToken::Semi + } else { + TrailingToken::None + }; + Ok((this.mk_stmt(lo.to(this.prev_token.span), StmtKind::Local(local)), trailing)) + }) + } + + fn recover_local_after_let(&mut self, lo: Span, attrs: AttrWrapper) -> PResult<'a, Stmt> { + self.collect_tokens_trailing_token(attrs, ForceCollect::No, |this, attrs| { + let local = this.parse_local(attrs.into())?; + // FIXME - maybe capture semicolon in recovery? + Ok(( + this.mk_stmt(lo.to(this.prev_token.span), StmtKind::Local(local)), + TrailingToken::None, + )) + }) + } + + /// Parses a local variable declaration. + fn parse_local(&mut self, attrs: AttrVec) -> PResult<'a, P> { + let lo = self.prev_token.span; + let (pat, colon) = self.parse_pat_before_ty(None, RecoverComma::Yes, "`let` bindings")?; + + let (err, ty) = 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)), + Err(mut err) => { + if let Ok(snip) = self.span_to_snippet(pat.span) { + err.span_label(pat.span, format!("while parsing the type for `{}`", snip)); + } + // 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) + } + } + } else { + (None, None) + }; + 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_short( + 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: ; + *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 kind = match init { + None => LocalKind::Decl, + Some(init) => { + if self.eat_keyword(kw::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(msg)); + } + let els = self.parse_block()?; + self.check_let_else_init_bool_expr(&init); + 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(P(ast::Local { ty, pat, kind, id: DUMMY_NODE_ID, span: lo.to(hi), 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.lazy() { + let suggs = vec![ + (init.span.shrink_to_lo(), "(".to_string()), + (init.span.shrink_to_hi(), ")".to_string()), + ]; + self.struct_span_err( + init.span, + &format!( + "a `{}` expression cannot be directly assigned in `let...else`", + op.node.to_string() + ), + ) + .multipart_suggestion( + "wrap the expression in parentheses", + suggs, + Applicability::MachineApplicable, + ) + .emit(); + } + } + } + + fn check_let_else_init_trailing_brace(&self, init: &ast::Expr) { + if let Some(trailing) = classify::expr_trailing_brace(init) { + let err_span = trailing.span.with_lo(trailing.span.hi() - BytePos(1)); + let suggs = vec![ + (trailing.span.shrink_to_lo(), "(".to_string()), + (trailing.span.shrink_to_hi(), ")".to_string()), + ]; + self.struct_span_err( + err_span, + "right curly brace `}` before `else` in a `let...else` statement not allowed", + ) + .multipart_suggestion( + "try wrapping the expression in parentheses", + suggs, + Applicability::MachineApplicable, + ) + .emit(); + } + } + + /// Parses the RHS of a local variable declaration (e.g., `= 14;`). + fn parse_initializer(&mut self, eq_optional: bool) -> PResult<'a, Option>> { + let eq_consumed = match self.token.kind { + token::BinOpEq(..) => { + // Recover `let x = 1` as `let x = 1` + self.struct_span_err( + self.token.span, + "can't reassign to an uninitialized variable", + ) + .span_suggestion_short( + self.token.span, + "initialize the variable", + "=", + Applicability::MaybeIncorrect, + ) + .help("if you meant to overwrite, remove the `let` binding") + .emit(); + self.bump(); + true + } + _ => self.eat(&token::Eq), + }; + + Ok(if eq_consumed || eq_optional { Some(self.parse_expr()?) } else { None }) + } + + /// Parses a block. No inner attributes are allowed. + pub(super) fn parse_block(&mut self) -> PResult<'a, P> { + let (attrs, block) = self.parse_inner_attrs_and_block()?; + if let [.., last] = &*attrs { + self.error_on_forbidden_inner_attr(last.span, DEFAULT_INNER_ATTR_FORBIDDEN); + } + Ok(block) + } + + fn error_block_no_opening_brace_msg( + &mut self, + msg: &str, + ) -> DiagnosticBuilder<'a, ErrorGuaranteed> { + let sp = self.token.span; + let mut e = self.struct_span_err(sp, msg); + let do_not_suggest_help = self.token.is_keyword(kw::In) || self.token == token::Colon; + + // 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) { + // 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(Some(_)) + if (!self.token.is_keyword(kw::Else) + && self.look_ahead(1, |t| t == &token::OpenDelim(Delimiter::Brace))) + || do_not_suggest_help => {} + // Do not suggest `if foo println!("") {;}` (as would be seen in test for #46836). + Ok(Some(Stmt { kind: StmtKind::Empty, .. })) => {} + Ok(Some(stmt)) => { + let stmt_own_line = self.sess.source_map().is_line_before_span_empty(sp); + let stmt_span = if stmt_own_line && self.eat(&token::Semi) { + // Expand the span to include the semicolon. + stmt.span.with_hi(self.prev_token.span.hi()) + } else { + stmt.span + }; + e.multipart_suggestion( + "try placing this code inside 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, + ); + } + Err(e) => { + self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore); + e.cancel(); + } + _ => {} + } + e.span_label(sp, "expected `{`"); + e + } + + fn error_block_no_opening_brace(&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(&msg)) + } + + /// Parses a block. Inner attributes are allowed. + pub(super) fn parse_inner_attrs_and_block( + &mut self, + ) -> PResult<'a, (Vec, P)> { + self.parse_block_common(self.token.span, BlockCheckMode::Default) + } + + /// Parses a block. Inner attributes are allowed. + pub(super) fn parse_block_common( + &mut self, + lo: Span, + blk_mode: BlockCheckMode, + ) -> PResult<'a, (Vec, P)> { + maybe_whole!(self, NtBlock, |x| (Vec::new(), x)); + + self.maybe_recover_unexpected_block_label(); + if !self.eat(&token::OpenDelim(Delimiter::Brace)) { + return self.error_block_no_opening_brace(); + } + + let attrs = self.parse_inner_attributes()?; + let tail = match self.maybe_suggest_struct_literal(lo, blk_mode) { + 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(crate) fn parse_block_tail( + &mut self, + lo: Span, + s: BlockCheckMode, + recover: AttemptLocalParseRecovery, + ) -> PResult<'a, P> { + let mut stmts = vec![]; + while !self.eat(&token::CloseDelim(Delimiter::Brace)) { + if self.token == token::Eof { + break; + } + let stmt = match self.parse_full_stmt(recover) { + Err(mut err) if recover.yes() => { + self.maybe_annotate_with_ascription(&mut err, false); + err.emit(); + self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore); + Some(self.mk_stmt_err(self.token.span)) + } + Ok(stmt) => stmt, + Err(err) => return Err(err), + }; + if let Some(stmt) = stmt { + stmts.push(stmt); + } else { + // Found only `;` or `}`. + continue; + }; + } + Ok(self.mk_block(stmts, s, lo.to(self.prev_token.span))) + } + + /// Parses a statement, including the trailing semicolon. + pub fn parse_full_stmt( + &mut self, + recover: AttemptLocalParseRecovery, + ) -> PResult<'a, Option> { + // Skip looking for a trailing semicolon when we have an interpolated statement. + maybe_whole!(self, NtStmt, |x| Some(x.into_inner())); + + let Some(mut stmt) = self.parse_stmt_without_recovery(true, ForceCollect::No)? else { + return Ok(None); + }; + + let mut eat_semi = true; + match stmt.kind { + // Expression without semicolon. + StmtKind::Expr(ref mut 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. + if let Err(mut e) = + self.expect_one_of(&[], &[token::Semi, token::CloseDelim(Delimiter::Brace)]) + { + if let TokenKind::DocComment(..) = self.token.kind { + if let Ok(snippet) = self.span_to_snippet(self.token.span) { + let sp = self.token.span; + let marker = &snippet[..3]; + let (comment_marker, doc_comment_marker) = marker.split_at(2); + + e.span_suggestion( + sp.with_hi(sp.lo() + BytePos(marker.len() as u32)), + &format!( + "add a space before `{}` to use a regular comment", + doc_comment_marker, + ), + format!("{} {}", comment_marker, doc_comment_marker), + Applicability::MaybeIncorrect, + ); + } + } + if let Err(mut e) = + self.check_mistyped_turbofish_with_multiple_type_params(e, expr) + { + if recover.no() { + return Err(e); + } + e.emit(); + self.recover_stmt(); + } + // Don't complain about type errors in body tail after parse error (#57383). + let sp = expr.span.to(self.prev_token.span); + *expr = self.mk_expr_err(sp); + } + } + StmtKind::Expr(_) | StmtKind::MacCall(_) => {} + StmtKind::Local(ref mut local) if let Err(e) = self.expect_semi() => { + // We might be at the `,` in `let x = foo;`. Try to recover. + match &mut local.kind { + LocalKind::Init(expr) | LocalKind::InitElse(expr, _) => { + self.check_mistyped_turbofish_with_multiple_type_params(e, expr)?; + // We found `foo`, have we fully recovered? + self.expect_semi()?; + } + LocalKind::Decl => return Err(e), + } + eat_semi = false; + } + StmtKind::Empty | StmtKind::Item(_) | StmtKind::Local(_) | StmtKind::Semi(_) => eat_semi = false, + } + + if eat_semi && self.eat(&token::Semi) { + stmt = stmt.add_trailing_semicolon(); + } + stmt.span = stmt.span.to(self.prev_token.span); + Ok(Some(stmt)) + } + + pub(super) fn mk_block(&self, stmts: Vec, rules: BlockCheckMode, span: Span) -> P { + P(Block { + stmts, + id: DUMMY_NODE_ID, + rules, + span, + tokens: None, + could_be_bare_literal: false, + }) + } + + 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) -> Stmt { + self.mk_stmt(span, StmtKind::Expr(self.mk_expr_err(span))) + } + + pub(super) fn mk_block_err(&self, span: Span) -> P { + self.mk_block(vec![self.mk_stmt_err(span)], BlockCheckMode::Default, span) + } +} -- cgit v1.2.3