+
+ /// If encountering `future.await()`, consume and emit error.
+ crate fn recover_from_await_method_call(&mut self) {
+ if self.token == token::OpenDelim(token::Paren) &&
+ self.look_ahead(1, |t| t == &token::CloseDelim(token::Paren))
+ {
+ // future.await()
+ let lo = self.span;
+ self.bump(); // (
+ let sp = lo.to(self.span);
+ self.bump(); // )
+ let mut err = self.struct_span_err(sp, "incorrect use of `await`");
+ err.span_suggestion(
+ sp,
+ "`await` is not a method call, remove the parentheses",
+ String::new(),
+ Applicability::MachineApplicable,
+ );
+ err.emit()
+ }
+ }
+
+ crate fn could_ascription_be_path(&self, node: &ast::ExprKind) -> bool {
+ self.token.is_ident() &&
+ if let ast::ExprKind::Path(..) = node { true } else { false } &&
+ !self.token.is_reserved_ident() && // v `foo:bar(baz)`
+ self.look_ahead(1, |t| t == &token::OpenDelim(token::Paren)) ||
+ self.look_ahead(1, |t| t == &token::Lt) && // `foo:bar<baz`
+ self.look_ahead(2, |t| t.is_ident()) ||
+ self.look_ahead(1, |t| t == &token::Colon) && // `foo:bar:baz`
+ self.look_ahead(2, |t| t.is_ident()) ||
+ self.look_ahead(1, |t| t == &token::ModSep) && // `foo:bar::baz`
+ self.look_ahead(2, |t| t.is_ident())
+ }
+
+ crate fn bad_type_ascription(
+ &self,
+ err: &mut DiagnosticBuilder<'a>,
+ lhs_span: Span,
+ cur_op_span: Span,
+ next_sp: Span,
+ maybe_path: bool,
+ ) {
+ err.span_label(self.span, "expecting a type here because of type ascription");
+ let cm = self.sess.source_map();
+ let next_pos = cm.lookup_char_pos(next_sp.lo());
+ let op_pos = cm.lookup_char_pos(cur_op_span.hi());
+ if op_pos.line != next_pos.line {
+ err.span_suggestion(
+ cur_op_span,
+ "try using a semicolon",
+ ";".to_string(),
+ Applicability::MaybeIncorrect,
+ );
+ } else {
+ if maybe_path {
+ err.span_suggestion(
+ cur_op_span,
+ "maybe you meant to write a path separator here",
+ "::".to_string(),
+ Applicability::MaybeIncorrect,
+ );
+ } else {
+ err.note("type ascription is a nightly-only feature that lets \
+ you annotate an expression with a type: `<expr>: <type>`");
+ err.span_note(
+ lhs_span,
+ "this expression expects an ascribed type after the colon",
+ );
+ err.help("this might be indicative of a syntax error elsewhere");
+ }
+ }
+ }
+
+ crate fn recover_seq_parse_error(
+ &mut self,
+ delim: token::DelimToken,
+ lo: Span,
+ result: PResult<'a, P<Expr>>,
+ ) -> P<Expr> {
+ match result {
+ Ok(x) => x,
+ Err(mut err) => {
+ err.emit();
+ // recover from parse error
+ self.consume_block(delim);
+ self.mk_expr(lo.to(self.prev_span), ExprKind::Err, ThinVec::new())
+ }
+ }
+ }
+
+ crate fn recover_closing_delimiter(
+ &mut self,
+ tokens: &[token::Token],
+ mut err: DiagnosticBuilder<'a>,
+ ) -> PResult<'a, bool> {
+ let mut pos = None;
+ // we want to use the last closing delim that would apply
+ for (i, unmatched) in self.unclosed_delims.iter().enumerate().rev() {
+ if tokens.contains(&token::CloseDelim(unmatched.expected_delim))
+ && Some(self.span) > unmatched.unclosed_span
+ {
+ pos = Some(i);
+ }
+ }
+ match pos {
+ Some(pos) => {
+ // Recover and assume that the detected unclosed delimiter was meant for
+ // this location. Emit the diagnostic and act as if the delimiter was
+ // present for the parser's sake.
+
+ // Don't attempt to recover from this unclosed delimiter more than once.
+ let unmatched = self.unclosed_delims.remove(pos);
+ let delim = TokenType::Token(token::CloseDelim(unmatched.expected_delim));
+
+ // We want to suggest the inclusion of the closing delimiter where it makes
+ // the most sense, which is immediately after the last token:
+ //
+ // {foo(bar {}}
+ // - ^
+ // | |
+ // | help: `)` may belong here (FIXME: #58270)
+ // |
+ // unclosed delimiter
+ if let Some(sp) = unmatched.unclosed_span {
+ err.span_label(sp, "unclosed delimiter");
+ }
+ err.span_suggestion_short(
+ self.sess.source_map().next_point(self.prev_span),
+ &format!("{} may belong here", delim.to_string()),
+ delim.to_string(),
+ Applicability::MaybeIncorrect,
+ );
+ err.emit();
+ self.expected_tokens.clear(); // reduce errors
+ Ok(true)
+ }
+ _ => Err(err),
+ }
+ }
+
+ /// Recover from `pub` keyword in places where it seems _reasonable_ but isn't valid.
+ crate fn eat_bad_pub(&mut self) {
+ if self.token.is_keyword(keywords::Pub) {
+ match self.parse_visibility(false) {
+ Ok(vis) => {
+ let mut err = self.diagnostic()
+ .struct_span_err(vis.span, "unnecessary visibility qualifier");
+ err.span_label(vis.span, "`pub` not permitted here");
+ err.emit();
+ }
+ Err(mut err) => err.emit(),
+ }
+ }
+ }
+
+ // Eat tokens until we can be relatively sure we reached the end of the
+ // statement. This is something of a best-effort heuristic.
+ //
+ // We terminate when we find an unmatched `}` (without consuming it).
+ crate fn recover_stmt(&mut self) {
+ self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore)
+ }
+
+ // If `break_on_semi` is `Break`, then we will stop consuming tokens after
+ // finding (and consuming) a `;` outside of `{}` or `[]` (note that this is
+ // approximate - it can mean we break too early due to macros, but that
+ // should only lead to sub-optimal recovery, not inaccurate parsing).
+ //
+ // If `break_on_block` is `Break`, then we will stop consuming tokens
+ // after finding (and consuming) a brace-delimited block.
+ crate fn recover_stmt_(&mut self, break_on_semi: SemiColonMode, break_on_block: BlockMode) {
+ let mut brace_depth = 0;
+ let mut bracket_depth = 0;
+ let mut in_block = false;
+ debug!("recover_stmt_ enter loop (semi={:?}, block={:?})",
+ break_on_semi, break_on_block);
+ loop {
+ debug!("recover_stmt_ loop {:?}", self.token);
+ match self.token {
+ token::OpenDelim(token::DelimToken::Brace) => {
+ brace_depth += 1;
+ self.bump();
+ if break_on_block == BlockMode::Break &&
+ brace_depth == 1 &&
+ bracket_depth == 0 {
+ in_block = true;
+ }
+ }
+ token::OpenDelim(token::DelimToken::Bracket) => {
+ bracket_depth += 1;
+ self.bump();
+ }
+ token::CloseDelim(token::DelimToken::Brace) => {
+ if brace_depth == 0 {
+ debug!("recover_stmt_ return - close delim {:?}", self.token);
+ break;
+ }
+ brace_depth -= 1;
+ self.bump();
+ if in_block && bracket_depth == 0 && brace_depth == 0 {
+ debug!("recover_stmt_ return - block end {:?}", self.token);
+ break;
+ }
+ }
+ token::CloseDelim(token::DelimToken::Bracket) => {
+ bracket_depth -= 1;
+ if bracket_depth < 0 {
+ bracket_depth = 0;
+ }
+ self.bump();
+ }
+ token::Eof => {
+ debug!("recover_stmt_ return - Eof");
+ break;
+ }
+ token::Semi => {
+ self.bump();
+ if break_on_semi == SemiColonMode::Break &&
+ brace_depth == 0 &&
+ bracket_depth == 0 {
+ debug!("recover_stmt_ return - Semi");
+ break;
+ }
+ }
+ token::Comma => {
+ if break_on_semi == SemiColonMode::Comma &&
+ brace_depth == 0 &&
+ bracket_depth == 0 {
+ debug!("recover_stmt_ return - Semi");
+ break;
+ } else {
+ self.bump();
+ }
+ }
+ _ => {
+ self.bump()
+ }
+ }
+ }
+ }
+
+ crate fn consume_block(&mut self, delim: token::DelimToken) {
+ let mut brace_depth = 0;
+ loop {
+ if self.eat(&token::OpenDelim(delim)) {
+ brace_depth += 1;
+ } else if self.eat(&token::CloseDelim(delim)) {
+ if brace_depth == 0 {
+ return;
+ } else {
+ brace_depth -= 1;
+ continue;
+ }
+ } else if self.token == token::Eof || self.eat(&token::CloseDelim(token::NoDelim)) {
+ return;
+ } else {
+ self.bump();
+ }
+ }
+ }
+