rustc_parse/lexer/
diagnostics.rs1use rustc_ast::token::Delimiter;
2use rustc_errors::Diag;
3use rustc_span::Span;
4use rustc_span::source_map::SourceMap;
5
6use super::UnmatchedDelim;
7
8#[derive(Default)]
9pub(super) struct TokenTreeDiagInfo {
10 pub open_braces: Vec<(Delimiter, Span)>,
12 pub unmatched_delims: Vec<UnmatchedDelim>,
13
14 pub last_unclosed_found_span: Option<Span>,
16
17 pub empty_block_spans: Vec<Span>,
19
20 pub matching_block_spans: Vec<(Span, Span)>,
23}
24
25pub(super) fn same_indentation_level(sm: &SourceMap, open_sp: Span, close_sp: Span) -> bool {
26 match (sm.span_to_margin(open_sp), sm.span_to_margin(close_sp)) {
27 (Some(open_padding), Some(close_padding)) => open_padding == close_padding,
28 _ => false,
29 }
30}
31
32fn report_missing_open_delim(err: &mut Diag<'_>, unmatched_delims: &[UnmatchedDelim]) -> bool {
35 let mut reported_missing_open = false;
36 for unmatch_brace in unmatched_delims.iter() {
37 if let Some(delim) = unmatch_brace.found_delim
38 && matches!(delim, Delimiter::Parenthesis | Delimiter::Bracket)
39 {
40 let missed_open = match delim {
41 Delimiter::Parenthesis => "(",
42 Delimiter::Bracket => "[",
43 _ => unreachable!(),
44 };
45 err.span_label(
46 unmatch_brace.found_span.shrink_to_lo(),
47 format!("missing open `{missed_open}` for this delimiter"),
48 );
49 reported_missing_open = true;
50 }
51 }
52 reported_missing_open
53}
54
55pub(super) fn report_suspicious_mismatch_block(
56 err: &mut Diag<'_>,
57 diag_info: &TokenTreeDiagInfo,
58 sm: &SourceMap,
59 delim: Delimiter,
60) {
61 if report_missing_open_delim(err, &diag_info.unmatched_delims) {
62 return;
63 }
64
65 let mut matched_spans: Vec<(Span, bool)> = diag_info
66 .matching_block_spans
67 .iter()
68 .map(|&(open, close)| (open.with_hi(close.lo()), same_indentation_level(sm, open, close)))
69 .collect();
70
71 matched_spans.sort_by_key(|(span, _)| span.lo());
73
74 for i in 0..matched_spans.len() {
77 let (block_span, same_ident) = matched_spans[i];
78 if same_ident {
79 for j in i + 1..matched_spans.len() {
80 let (inner_block, inner_same_ident) = matched_spans[j];
81 if block_span.contains(inner_block) && !inner_same_ident {
82 matched_spans[j] = (inner_block, true);
83 }
84 }
85 }
86 }
87
88 let candidate_span =
90 matched_spans.into_iter().rev().find(|&(_, same_ident)| !same_ident).map(|(span, _)| span);
91
92 if let Some(block_span) = candidate_span {
93 err.span_label(block_span.shrink_to_lo(), "this delimiter might not be properly closed...");
94 err.span_label(
95 block_span.shrink_to_hi(),
96 "...as it matches this but it has different indentation",
97 );
98
99 if delim == Delimiter::Brace {
101 for span in diag_info.empty_block_spans.iter() {
102 if block_span.contains(*span) {
103 err.span_label(*span, "block is empty, you might have not meant to close it");
104 break;
105 }
106 }
107 }
108 } else {
109 if let Some(parent) = diag_info.matching_block_spans.last()
111 && diag_info.open_braces.last().is_none()
112 && diag_info.empty_block_spans.iter().all(|&sp| sp != parent.0.to(parent.1))
113 {
114 err.span_label(parent.0, "this opening brace...");
115 err.span_label(parent.1, "...matches this closing brace");
116 }
117 }
118}