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Improve unexpected close and mismatch delimiter hint in TokenTreesReader
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,119 @@ | ||
| use super::UnmatchedBrace; | ||
| use rustc_ast::token::Delimiter; | ||
| use rustc_errors::Diagnostic; | ||
| use rustc_span::source_map::SourceMap; | ||
| use rustc_span::Span; | ||
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| #[derive(Default)] | ||
| pub struct TokenTreeDiagInfo { | ||
| /// Stack of open delimiters and their spans. Used for error message. | ||
| pub open_braces: Vec<(Delimiter, Span)>, | ||
| pub unmatched_braces: Vec<UnmatchedBrace>, | ||
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| /// Used only for error recovery when arriving to EOF with mismatched braces. | ||
| pub last_unclosed_found_span: Option<Span>, | ||
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| /// Collect empty block spans that might have been auto-inserted by editors. | ||
| pub empty_block_spans: Vec<Span>, | ||
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| /// Collect the spans of braces (Open, Close). Used only | ||
| /// for detecting if blocks are empty and only braces. | ||
| pub matching_block_spans: Vec<(Span, Span)>, | ||
| } | ||
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| pub fn same_identation_level(sm: &SourceMap, open_sp: Span, close_sp: Span) -> bool { | ||
| match (sm.span_to_margin(open_sp), sm.span_to_margin(close_sp)) { | ||
| (Some(open_padding), Some(close_padding)) => open_padding == close_padding, | ||
| _ => false, | ||
| } | ||
| } | ||
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| // When we get a `)` or `]` for `{`, we should emit help message here | ||
| // it's more friendly compared to report `unmatched error` in later phase | ||
| pub fn report_missing_open_delim( | ||
| err: &mut Diagnostic, | ||
| unmatched_braces: &[UnmatchedBrace], | ||
| ) -> bool { | ||
| let mut reported_missing_open = false; | ||
| for unmatch_brace in unmatched_braces.iter() { | ||
| if let Some(delim) = unmatch_brace.found_delim | ||
| && matches!(delim, Delimiter::Parenthesis | Delimiter::Bracket) | ||
| { | ||
| let missed_open = match delim { | ||
| Delimiter::Parenthesis => "(", | ||
| Delimiter::Bracket => "[", | ||
| _ => unreachable!(), | ||
| }; | ||
| err.span_label( | ||
| unmatch_brace.found_span.shrink_to_lo(), | ||
| format!("missing open `{}` for this delimiter", missed_open), | ||
| ); | ||
| reported_missing_open = true; | ||
| } | ||
| } | ||
| reported_missing_open | ||
| } | ||
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| pub fn report_suspicious_mismatch_block( | ||
| err: &mut Diagnostic, | ||
| diag_info: &TokenTreeDiagInfo, | ||
| sm: &SourceMap, | ||
| delim: Delimiter, | ||
| ) { | ||
| if report_missing_open_delim(err, &diag_info.unmatched_braces) { | ||
| return; | ||
| } | ||
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| let mut matched_spans: Vec<(Span, bool)> = diag_info | ||
| .matching_block_spans | ||
| .iter() | ||
| .map(|&(open, close)| (open.with_hi(close.lo()), same_identation_level(sm, open, close))) | ||
| .collect(); | ||
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| // sort by `lo`, so the large block spans in the front | ||
| matched_spans.sort_by(|a, b| a.0.lo().cmp(&b.0.lo())); | ||
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| // We use larger block whose identation is well to cover those inner mismatched blocks | ||
| // O(N^2) here, but we are on error reporting path, so it is fine | ||
| for i in 0..matched_spans.len() { | ||
| let (block_span, same_ident) = matched_spans[i]; | ||
| if same_ident { | ||
| for j in i + 1..matched_spans.len() { | ||
| let (inner_block, inner_same_ident) = matched_spans[j]; | ||
| if block_span.contains(inner_block) && !inner_same_ident { | ||
| matched_spans[j] = (inner_block, true); | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
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||
| // Find the inner-most span candidate for final report | ||
| let candidate_span = | ||
| matched_spans.into_iter().rev().find(|&(_, same_ident)| !same_ident).map(|(span, _)| span); | ||
|
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| if let Some(block_span) = candidate_span { | ||
| err.span_label(block_span.shrink_to_lo(), "this delimiter might not be properly closed..."); | ||
| err.span_label( | ||
| block_span.shrink_to_hi(), | ||
| "...as it matches this but it has different indentation", | ||
| ); | ||
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| // If there is a empty block in the mismatched span, note it | ||
| if delim == Delimiter::Brace { | ||
| for span in diag_info.empty_block_spans.iter() { | ||
| if block_span.contains(*span) { | ||
| err.span_label(*span, "block is empty, you might have not meant to close it"); | ||
| break; | ||
| } | ||
| } | ||
| } | ||
| } else { | ||
| // If there is no suspicious span, give the last properly closed block may help | ||
| if let Some(parent) = diag_info.matching_block_spans.last() | ||
| && diag_info.open_braces.last().is_none() | ||
| && diag_info.empty_block_spans.iter().all(|&sp| sp != parent.0.to(parent.1)) { | ||
| err.span_label(parent.0, "this opening brace..."); | ||
| err.span_label(parent.1, "...matches this closing brace"); | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,4 +1,3 @@ | ||
| // error-pattern: this file contains an unclosed delimiter | ||
| #![feature(let_chains)] | ||
| trait Demo {} | ||
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