diff options
Diffstat (limited to 'src/librustc_parse/parser/expr.rs')
| -rw-r--r-- | src/librustc_parse/parser/expr.rs | 131 |
1 files changed, 100 insertions, 31 deletions
diff --git a/src/librustc_parse/parser/expr.rs b/src/librustc_parse/parser/expr.rs index 16ea2773b20..7f6f90431fc 100644 --- a/src/librustc_parse/parser/expr.rs +++ b/src/librustc_parse/parser/expr.rs @@ -673,10 +673,28 @@ impl<'a> Parser<'a> { /// Parse `& mut? <expr>` or `& raw [ const | mut ] <expr>`. fn parse_borrow_expr(&mut self, lo: Span) -> PResult<'a, (Span, ExprKind)> { self.expect_and()?; + let has_lifetime = self.token.is_lifetime() && self.look_ahead(1, |t| t != &token::Colon); + let lifetime = has_lifetime.then(|| self.expect_lifetime()); // For recovery, see below. let (borrow_kind, mutbl) = self.parse_borrow_modifiers(lo); let expr = self.parse_prefix_expr(None); - let (span, expr) = self.interpolated_or_expr_span(expr)?; - Ok((lo.to(span), ExprKind::AddrOf(borrow_kind, mutbl, expr))) + let (hi, expr) = 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); + } + Ok((span, ExprKind::AddrOf(borrow_kind, mutbl, expr))) + } + + fn error_remove_borrow_lifetime(&self, span: Span, lt_span: Span) { + self.struct_span_err(span, "borrow expressions cannot be annotated with lifetimes") + .span_label(lt_span, "annotated with lifetime here") + .span_suggestion( + lt_span, + "remove the lifetime annotation", + String::new(), + Applicability::MachineApplicable, + ) + .emit(); } /// Parse `mut?` or `raw [ const | mut ]`. @@ -901,7 +919,7 @@ impl<'a> Parser<'a> { } else if self.eat_lt() { let (qself, path) = self.parse_qpath(PathStyle::Expr)?; Ok(self.mk_expr(lo.to(path.span), ExprKind::Path(Some(qself), path), attrs)) - } else if self.token.is_path_start() { + } else if self.check_path() { self.parse_path_start_expr(attrs) } else if self.check_keyword(kw::Move) || self.check_keyword(kw::Static) { self.parse_closure_expr(attrs) @@ -1067,26 +1085,44 @@ impl<'a> Parser<'a> { self.maybe_recover_from_bad_qpath(expr, true) } + /// Parse `'label: $expr`. The label is already parsed. fn parse_labeled_expr(&mut self, label: Label, attrs: AttrVec) -> PResult<'a, P<Expr>> { let lo = label.ident.span; - self.expect(&token::Colon)?; - if self.eat_keyword(kw::While) { - return self.parse_while_expr(Some(label), lo, attrs); - } - if self.eat_keyword(kw::For) { - return self.parse_for_expr(Some(label), lo, attrs); - } - if self.eat_keyword(kw::Loop) { - return self.parse_loop_expr(Some(label), lo, attrs); - } - if self.token == token::OpenDelim(token::Brace) { - return self.parse_block_expr(Some(label), lo, BlockCheckMode::Default, attrs); + let label = Some(label); + let ate_colon = self.eat(&token::Colon); + let expr = if self.eat_keyword(kw::While) { + self.parse_while_expr(label, lo, attrs) + } else if self.eat_keyword(kw::For) { + self.parse_for_expr(label, lo, attrs) + } else if self.eat_keyword(kw::Loop) { + self.parse_loop_expr(label, lo, attrs) + } else if self.check(&token::OpenDelim(token::Brace)) || self.token.is_whole_block() { + self.parse_block_expr(label, lo, BlockCheckMode::Default, attrs) + } else { + let msg = "expected `while`, `for`, `loop` or `{` after a label"; + self.struct_span_err(self.token.span, msg).span_label(self.token.span, msg).emit(); + // Continue as an expression in an effort to recover on `'label: non_block_expr`. + self.parse_expr() + }?; + + if !ate_colon { + self.error_labeled_expr_must_be_followed_by_colon(lo, expr.span); } - let msg = "expected `while`, `for`, `loop` or `{` after a label"; - self.struct_span_err(self.token.span, msg).span_label(self.token.span, msg).emit(); - // Continue as an expression in an effort to recover on `'label: non_block_expr`. - self.parse_expr() + Ok(expr) + } + + fn error_labeled_expr_must_be_followed_by_colon(&self, lo: Span, span: Span) { + self.struct_span_err(span, "labeled expression must be followed by `:`") + .span_label(lo, "the label") + .span_suggestion_short( + lo.shrink_to_hi(), + "add `:` after the label", + ": ".to_string(), + Applicability::MachineApplicable, + ) + .note("labels are used before loops and blocks, allowing e.g., `break 'label` to them") + .emit(); } /// Recover on the syntax `do catch { ... }` suggesting `try { ... }` instead. @@ -1363,18 +1399,20 @@ impl<'a> Parser<'a> { opt_label: Option<Label>, lo: Span, blk_mode: BlockCheckMode, - outer_attrs: AttrVec, + mut attrs: AttrVec, ) -> PResult<'a, P<Expr>> { if let Some(label) = opt_label { self.sess.gated_spans.gate(sym::label_break_value, label.ident.span); } - self.expect(&token::OpenDelim(token::Brace))?; - - let mut attrs = outer_attrs; - attrs.extend(self.parse_inner_attributes()?); + if self.token.is_whole_block() { + self.struct_span_err(self.token.span, "cannot use a `block` macro fragment here") + .span_label(lo.to(self.token.span), "the `block` fragment is within this context") + .emit(); + } - let blk = self.parse_block_tail(lo, blk_mode)?; + let (inner_attrs, blk) = self.parse_block_common(lo, blk_mode)?; + attrs.extend(inner_attrs); Ok(self.mk_expr(blk.span, ExprKind::Block(blk, opt_label), attrs)) } @@ -1476,13 +1514,16 @@ impl<'a> Parser<'a> { let thn = if self.eat_keyword(kw::Else) || !cond.returns() { self.error_missing_if_cond(lo, cond.span) } else { + let attrs = self.parse_outer_attributes()?; // For recovery. let not_block = self.token != token::OpenDelim(token::Brace); - self.parse_block().map_err(|mut err| { + let block = self.parse_block().map_err(|mut err| { if not_block { err.span_label(lo, "this `if` expression has a condition, but no block"); } err - })? + })?; + self.error_on_if_block_attrs(lo, false, block.span, &attrs); + block }; let els = if self.eat_keyword(kw::Else) { Some(self.parse_else_expr()?) } else { None }; Ok(self.mk_expr(lo.to(self.prev_token.span), ExprKind::If(cond, thn, els), attrs)) @@ -1524,12 +1565,40 @@ impl<'a> Parser<'a> { /// Parses an `else { ... }` expression (`else` token already eaten). fn parse_else_expr(&mut self) -> PResult<'a, P<Expr>> { - if self.eat_keyword(kw::If) { - self.parse_if_expr(AttrVec::new()) + let ctx_span = self.prev_token.span; // `else` + let attrs = self.parse_outer_attributes()?; // For recovery. + let expr = if self.eat_keyword(kw::If) { + self.parse_if_expr(AttrVec::new())? } else { let blk = self.parse_block()?; - Ok(self.mk_expr(blk.span, ExprKind::Block(blk, None), AttrVec::new())) - } + self.mk_expr(blk.span, ExprKind::Block(blk, None), AttrVec::new()) + }; + self.error_on_if_block_attrs(ctx_span, true, expr.span, &attrs); + Ok(expr) + } + + fn error_on_if_block_attrs( + &self, + ctx_span: Span, + is_ctx_else: bool, + branch_span: Span, + attrs: &[ast::Attribute], + ) { + let (span, last) = match attrs { + [] => return, + [x0 @ xn] | [x0, .., xn] => (x0.span.to(xn.span), xn.span), + }; + let ctx = if is_ctx_else { "else" } else { "if" }; + self.struct_span_err(last, "outer attributes are not allowed on `if` and `else` branches") + .span_label(branch_span, "the attributes are attached to this branch") + .span_label(ctx_span, format!("the branch belongs to this `{}`", ctx)) + .span_suggestion( + span, + "remove the attributes", + String::new(), + Applicability::MachineApplicable, + ) + .emit(); } /// Parses `for <src_pat> in <src_expr> <src_loop_block>` (`for` token already eaten). |