--- /dev/null
+use super::attr::DEFAULT_INNER_ATTR_FORBIDDEN;
+use super::diagnostics::{AttemptLocalParseRecovery, Error};
+use super::expr::LhsExpr;
+use super::pat::{GateOr, RecoverComma};
+use super::path::PathStyle;
+use super::{BlockMode, ForceCollect, Parser, Restrictions, SemiColonMode, TrailingToken};
+use crate::{maybe_collect_tokens, maybe_whole};
+
+use rustc_ast as ast;
+use rustc_ast::attr::HasAttrs;
+use rustc_ast::ptr::P;
+use rustc_ast::token::{self, TokenKind};
+use rustc_ast::util::classify;
+use rustc_ast::{AttrStyle, AttrVec, Attribute, MacCall, MacCallStmt, MacStmtStyle};
+use rustc_ast::{Block, BlockCheckMode, Expr, ExprKind, Local, Stmt, StmtKind, DUMMY_NODE_ID};
+use rustc_errors::{Applicability, 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<Stmt>> {
+ 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
+ fn parse_stmt_without_recovery(
+ &mut self,
+ capture_semi: bool,
+ force_collect: ForceCollect,
+ ) -> PResult<'a, Option<Stmt>> {
+ let mut attrs = self.parse_outer_attributes()?;
+ let lo = self.token.span;
+
+ maybe_whole!(self, NtStmt, |stmt| {
+ let mut stmt = stmt;
+ stmt.visit_attrs(|stmt_attrs| {
+ mem::swap(stmt_attrs, &mut attrs);
+ stmt_attrs.extend(attrs);
+ });
+ Some(stmt)
+ });
+
+ Ok(Some(if self.token.is_keyword(kw::Let) {
+ self.parse_local_mk(lo, attrs.into(), capture_semi, force_collect)?
+ } else if self.is_kw_followed_by_ident(kw::Mut) {
+ self.recover_stmt_local(lo, attrs.into(), "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.into(), 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.into(), 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_`.
+ self.parse_stmt_path_start(lo, attrs, force_collect)?
+ } else if let Some(item) =
+ self.parse_item_common(attrs.clone(), false, true, |_| 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);
+ self.mk_stmt(lo, StmtKind::Empty)
+ } else if self.token != token::CloseDelim(token::Brace) {
+ // Remainder are line-expr stmts.
+ let e = self.parse_expr_res(Restrictions::STMT_EXPR, Some(attrs.into()))?;
+ self.mk_stmt(lo.to(e.span), StmtKind::Expr(e))
+ } else {
+ self.error_outer_attrs(&attrs);
+ return Ok(None);
+ }))
+ }
+
+ fn parse_stmt_path_start(
+ &mut self,
+ lo: Span,
+ attrs: Vec<Attribute>,
+ force_collect: ForceCollect,
+ ) -> PResult<'a, Stmt> {
+ maybe_collect_tokens!(self, force_collect, &attrs, |this: &mut Parser<'a>| {
+ 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(token::Brace)) {
+ this.parse_struct_expr(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| {
+ let expr = this.parse_dot_or_call_expr_with(expr, lo, attrs.into())?;
+ this.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(expr))
+ })?;
+ Ok((
+ this.mk_stmt(lo.to(this.prev_token.span), StmtKind::Expr(expr)),
+ TrailingToken::None,
+ ))
+ })
+ }
+
+ /// 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 =
+ if delim == token::Brace { MacStmtStyle::Braces } else { MacStmtStyle::NoBraces };
+
+ let mac = MacCall { path, args, prior_type_ascription: self.last_type_ascription };
+
+ let kind = if delim == token::Brace || 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, true)?;
+ let e = self.parse_dot_or_call_expr_with(e, lo, attrs)?;
+ 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_fatal_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: AttrVec,
+ 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.to_string(), Applicability::MachineApplicable)
+ .emit();
+ Ok(stmt)
+ }
+
+ fn parse_local_mk(
+ &mut self,
+ lo: Span,
+ attrs: AttrVec,
+ capture_semi: bool,
+ force_collect: ForceCollect,
+ ) -> PResult<'a, Stmt> {
+ maybe_collect_tokens!(self, force_collect, &attrs, |this: &mut Parser<'a>| {
+ 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: AttrVec) -> PResult<'a, Stmt> {
+ let local = self.parse_local(attrs.into())?;
+ Ok(self.mk_stmt(lo.to(self.prev_token.span), StmtKind::Local(local)))
+ }
+
+ /// Parses a local variable declaration.
+ fn parse_local(&mut self, attrs: AttrVec) -> PResult<'a, P<Local>> {
+ let lo = self.prev_token.span;
+ let pat = self.parse_top_pat(GateOr::Yes, RecoverComma::Yes)?;
+
+ let (err, ty) = if self.eat(&token::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));
+ }
+ let err = if self.check(&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",
+ " =".to_string(),
+ 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(mut 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 hi = if self.token == token::Semi { self.token.span } else { self.prev_token.span };
+ Ok(P(ast::Local { ty, pat, init, id: DUMMY_NODE_ID, span: lo.to(hi), attrs, tokens: None }))
+ }
+
+ /// Parses the RHS of a local variable declaration (e.g., '= 14;').
+ fn parse_initializer(&mut self, eq_optional: bool) -> PResult<'a, Option<P<Expr>>> {
+ let eq_consumed = match self.token.kind {
+ token::BinOpEq(..) => {
+ // Recover `let x <op>= 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",
+ "=".to_string(),
+ Applicability::MaybeIncorrect,
+ )
+ .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<Block>> {
+ 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<T>(&mut self) -> PResult<'a, T> {
+ let sp = self.token.span;
+ let tok = super::token_descr(&self.token);
+ let mut e = self.struct_span_err(sp, &format!("expected `{{`, found {}", tok));
+ 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., `if a b {`), the place-
+ // inside-a-block suggestion would be more likely wrong than right.
+ Ok(Some(_))
+ if self.look_ahead(1, |t| t == &token::OpenDelim(token::Brace))
+ || do_not_suggest_help => {}
+ 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
+ };
+ if let Ok(snippet) = self.span_to_snippet(stmt_span) {
+ e.span_suggestion(
+ stmt_span,
+ "try placing this code inside a block",
+ format!("{{ {} }}", snippet),
+ // Speculative; has been misleading in the past (#46836).
+ Applicability::MaybeIncorrect,
+ );
+ }
+ }
+ Err(mut e) => {
+ self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
+ e.cancel();
+ }
+ _ => {}
+ }
+ e.span_label(sp, "expected `{`");
+ Err(e)
+ }
+
+ /// Parses a block. Inner attributes are allowed.
+ pub(super) fn parse_inner_attrs_and_block(
+ &mut self,
+ ) -> PResult<'a, (Vec<Attribute>, P<Block>)> {
+ 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<Attribute>, P<Block>)> {
+ maybe_whole!(self, NtBlock, |x| (Vec::new(), x));
+
+ if !self.eat(&token::OpenDelim(token::Brace)) {
+ return self.error_block_no_opening_brace();
+ }
+
+ let attrs = self.parse_inner_attributes()?;
+ let tail = if let Some(tail) = self.maybe_suggest_struct_literal(lo, blk_mode) {
+ tail?
+ } else {
+ 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 '{'.
+ crate fn parse_block_tail(
+ &mut self,
+ lo: Span,
+ s: BlockCheckMode,
+ recover: AttemptLocalParseRecovery,
+ ) -> PResult<'a, P<Block>> {
+ let mut stmts = vec![];
+ while !self.eat(&token::CloseDelim(token::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<Stmt>> {
+ // Skip looking for a trailing semicolon when we have an interpolated statement.
+ maybe_whole!(self, NtStmt, |x| Some(x));
+
+ let mut stmt = match self.parse_stmt_without_recovery(true, ForceCollect::No)? {
+ Some(stmt) => stmt,
+ None => 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(token::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<bar, baz>;`. Try to recover.
+ match &mut local.init {
+ Some(ref mut expr) => {
+ self.check_mistyped_turbofish_with_multiple_type_params(e, expr)?;
+ // We found `foo<bar, baz>`, have we fully recovered?
+ self.expect_semi()?;
+ }
+ None => return Err(e),
+ }
+ }
+ eat_semi = false;
+ }
+ StmtKind::Empty | StmtKind::Item(_) | 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<Stmt>, rules: BlockCheckMode, span: Span) -> P<Block> {
+ P(Block { stmts, id: DUMMY_NODE_ID, rules, span, tokens: None })
+ }
+
+ 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<Block> {
+ self.mk_block(vec![self.mk_stmt_err(span)], BlockCheckMode::Default, span)
+ }
+}
projects / rustc.git / blobdiff