diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs index 716ababb0080..c1cca1186af4 100644 --- a/compiler/rustc_parse/src/parser/diagnostics.rs +++ b/compiler/rustc_parse/src/parser/diagnostics.rs @@ -2874,7 +2874,12 @@ pub(crate) fn maybe_recover_colon_colon_in_pat_typo( first_pat } - pub(crate) fn maybe_recover_unexpected_block_label(&mut self) -> bool { + /// 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(crate) fn maybe_recover_unexpected_block_label( + &mut self, + loop_header: Option, + ) -> bool { // Check for `'a : {` if !(self.check_lifetime() && self.look_ahead(1, |t| *t == token::Colon) @@ -2885,16 +2890,28 @@ pub(crate) fn maybe_recover_unexpected_block_label(&mut self) -> bool { let label = self.eat_label().expect("just checked if a label exists"); self.bump(); // eat `:` let span = label.ident.span.to(self.prev_token.span); - self.dcx() + let mut diag = self + .dcx() .struct_span_err(span, "block label not supported here") - .with_span_label(span, "not supported here") - .with_tool_only_span_suggestion( + .with_span_label(span, "not supported here"); + if let Some(loop_header) = loop_header { + diag.multipart_suggestion( + "if you meant to label the loop, move this label before the loop", + vec![ + (label.ident.span.until(self.token.span), String::from("")), + (loop_header.shrink_to_lo(), format!("{}: ", label.ident)), + ], + Applicability::MachineApplicable, + ); + } else { + diag.tool_only_span_suggestion( label.ident.span.until(self.token.span), "remove this block label", "", Applicability::MachineApplicable, - ) - .emit(); + ); + } + diag.emit(); true } diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs index 0774324eae74..cd931888fbaa 100644 --- a/compiler/rustc_parse/src/parser/expr.rs +++ b/compiler/rustc_parse/src/parser/expr.rs @@ -2286,7 +2286,7 @@ pub(super) fn parse_expr_block( }); } - let (attrs, blk) = self.parse_block_common(lo, blk_mode, true)?; + let (attrs, blk) = self.parse_block_common(lo, blk_mode, true, None)?; Ok(self.mk_expr_with_attrs(blk.span, ExprKind::Block(blk, opt_label), attrs)) } @@ -2851,7 +2851,11 @@ fn parse_expr_for(&mut self, opt_label: Option