Account for tabs when highlighting multiline code suggestions

Author: estebank

compiler/rustc_errors/src/emitter.rs

@@ -1623,7 +1623,7 @@ impl EmitterWriter {
  let line_start = sm.lookup_char_pos(parts[0].span.lo()).line;
  draw_col_separator_no_space(&mut buffer, 1, max_line_num_len + 1);
  let mut lines = complete.lines();
- for (line_pos, (line, parts)) in
+ for (line_pos, (line, highlight_parts)) in
  lines.by_ref().zip(highlights).take(MAX_SUGGESTION_HIGHLIGHT_LINES).enumerate()
  {
  // Print the span column to avoid confusion
@@ -1658,7 +1658,7 @@ impl EmitterWriter {
  );
  buffer.puts(row_num, max_line_num_len + 1, "+ ", Style::Addition);
  } else if is_multiline {
- match &parts[..] {
+ match &highlight_parts[..] {
  [SubstitutionHighlight { start: 0, end }] if *end == line.len() => {
  buffer.puts(row_num, max_line_num_len + 1, "+ ", Style::Addition);
  }
@@ -1676,16 +1676,33 @@ impl EmitterWriter {
  // print the suggestion
  buffer.append(row_num, &replace_tabs(line), Style::NoStyle);
 
- if is_multiline {
- for SubstitutionHighlight { start, end } in parts {
- buffer.set_style_range(
- row_num,
- max_line_num_len + 3 + start,
- max_line_num_len + 3 + end,
- Style::Addition,
- true,
- );
- }
+ // Colorize addition/replacements with green.
+ for &SubstitutionHighlight { start, end } in highlight_parts {
+ // Account for tabs when highlighting (#87972).
+ let start: usize = line
+ .chars()
+ .take(start)
+ .map(|ch| match ch {
+ '\t' => 4,
+ _ => 1,
+ })
+ .sum();
+
+ let end: usize = line
+ .chars()
+ .take(end)
+ .map(|ch| match ch {
+ '\t' => 4,
+ _ => 1,
+ })
+ .sum();
+ buffer.set_style_range(
+ row_num,
+ max_line_num_len + 3 + start,
+ max_line_num_len + 3 + end,
+ Style::Addition,
+ true,
+ );
  }
  row_num += 1;
  }
@@ -1723,13 +1740,6 @@ impl EmitterWriter {
  assert!(underline_start >= 0 && underline_end >= 0);
  let padding: usize = max_line_num_len + 3;
  for p in underline_start..underline_end {
- // Colorize addition/replacements with green.
- buffer.set_style(
- row_num - 1,
- (padding as isize + p) as usize,
- Style::Addition,
- true,
- );
  if !show_diff {
  // If this is a replacement, underline with `^`, if this is an addition
  // underline with `+`.

compiler/rustc_errors/src/lib.rs

@@ -283,20 +283,25 @@ impl CodeSuggestion {
  let mut buf = String::new();
 
  let mut line_highlight = vec![];
+ // We need to keep track of the difference between the existing code and the added
+ // or deleted code in order to point at the correct column *after* substitution.
+ let mut acc = 0;
  for part in &substitution.parts {
  let cur_lo = sm.lookup_char_pos(part.span.lo());
  if prev_hi.line == cur_lo.line {
  let mut count =
  push_trailing(&mut buf, prev_line.as_ref(), &prev_hi, Some(&cur_lo));
  while count > 0 {
  highlights.push(std::mem::take(&mut line_highlight));
+ acc = 0;
  count -= 1;
  }
  } else {
  highlights.push(std::mem::take(&mut line_highlight));
  let mut count = push_trailing(&mut buf, prev_line.as_ref(), &prev_hi, None);
  while count > 0 {
  highlights.push(std::mem::take(&mut line_highlight));
+ acc = 0;
  count -= 1;
  }
  // push lines between the previous and current span (if any)
@@ -305,6 +310,7 @@ impl CodeSuggestion {
  buf.push_str(line.as_ref());
  buf.push('\n');
  highlights.push(std::mem::take(&mut line_highlight));
+ acc = 0;
  }
  }
  if let Some(cur_line) = sf.get_line(cur_lo.line - 1) {
@@ -316,18 +322,22 @@ impl CodeSuggestion {
  }
  }
  // Add a whole line highlight per line in the snippet.
+ let len = part.snippet.split('\n').next().unwrap_or(&part.snippet).len();
  line_highlight.push(SubstitutionHighlight {
- start: cur_lo.col.0,
- end: cur_lo.col.0
- + part.snippet.split('\n').next().unwrap_or(&part.snippet).len(),
+ start: (cur_lo.col.0 as isize + acc) as usize,
+ end: (cur_lo.col.0 as isize + acc + len as isize) as usize,
  });
+ buf.push_str(&part.snippet);
+ prev_hi = sm.lookup_char_pos(part.span.hi());
+ if prev_hi.line == cur_lo.line {
+ acc += len as isize - (prev_hi.col.0 - cur_lo.col.0) as isize;
+ }
+ prev_line = sf.get_line(prev_hi.line - 1);
  for line in part.snippet.split('\n').skip(1) {
+ acc = 0;
  highlights.push(std::mem::take(&mut line_highlight));
  line_highlight.push(SubstitutionHighlight { start: 0, end: line.len() });
  }
- buf.push_str(&part.snippet);
- prev_hi = sm.lookup_char_pos(part.span.hi());
- prev_line = sf.get_line(prev_hi.line - 1);
  }
  highlights.push(std::mem::take(&mut line_highlight));
  let only_capitalization = is_case_difference(sm, &buf, bounding_span);