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Show multiline spans in full if short enough
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When dealing with multiline spans that span few lines, show the complete
span instead of restricting to the first character of the first line.

For example, instead of:

```
% ./rustc file2.rs
error[E0277]: the trait bound `{integer}: std::ops::Add<()>` is not satisfied
  --> file2.rs:13:9
   |
13 |    foo(1 + bar(x,
   |        ^ trait `{integer}: std::ops::Add<()>` not satisfied
   |
```

show

```
% ./rustc file2.rs
error[E0277]: the trait bound `{integer}: std::ops::Add<()>` is not satisfied
  --> file2.rs:13:9
   |
13 |      foo(1 + bar(x,
   |  ________^ starting here...
14 | |            y),
   | |_____________^ ...ending here: trait `{integer}: std::ops::Add<()>` not satisfied
   |
```
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@estebank
estebank committed Oct 25, 2016
1 parent b5f6d7e commit 41c9950
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Showing 6 changed files with 335 additions and 60 deletions.
216 changes: 165 additions & 51 deletions src/librustc_errors/emitter.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@ use syntax_pos::{COMMAND_LINE_SP, DUMMY_SP, FileMap, Span, MultiSpan, CharPos};

use {Level, CodeSuggestion, DiagnosticBuilder, SubDiagnostic, CodeMapper};
use RenderSpan::*;
use snippet::{StyledString, Style, Annotation, Line};
use snippet::{Annotation, AnnotationType, Line, StyledString, Style};
use styled_buffer::StyledBuffer;

use std::io::prelude::*;
Expand Down Expand Up @@ -65,6 +65,7 @@ pub struct EmitterWriter {
struct FileWithAnnotatedLines {
file: Rc<FileMap>,
lines: Vec<Line>,
multiline_depth: usize,
}


Expand Down Expand Up @@ -137,10 +138,12 @@ impl EmitterWriter {
line_index: line_index,
annotations: vec![ann],
}],
multiline_depth: 0,
});
}

let mut output = vec![];
let mut multiline_annotations = vec![];

if let Some(ref cm) = self.cm {
for span_label in msp.span_labels() {
Expand All @@ -151,8 +154,9 @@ impl EmitterWriter {
let mut hi = cm.lookup_char_pos(span_label.span.hi);
let mut is_minimized = false;

// If the span is multi-line, simplify down to the span of one character
if lo.line != hi.line {
// If the span is long multi-line, simplify down to the span of one character
let max_multiline_span_length = 8;
if lo.line != hi.line && (hi.line - lo.line) > max_multiline_span_length {
hi.line = lo.line;
hi.col = CharPos(lo.col.0 + 1);
is_minimized = true;
Expand All @@ -163,37 +167,92 @@ impl EmitterWriter {
// 6..7. This is degenerate input, but it's best to degrade
// gracefully -- and the parser likes to supply a span like
// that for EOF, in particular.
if lo.col == hi.col {
if lo.col == hi.col && lo.line == hi.line {
hi.col = CharPos(lo.col.0 + 1);
}

add_annotation_to_file(&mut output,
lo.file,
lo.line,
Annotation {
start_col: lo.col.0,
end_col: hi.col.0,
is_primary: span_label.is_primary,
is_minimized: is_minimized,
label: span_label.label.clone(),
});
let mut ann = Annotation {
start_col: lo.col.0,
end_col: hi.col.0,
is_primary: span_label.is_primary,
label: span_label.label.clone(),
annotation_type: AnnotationType::Singleline,
};
if is_minimized {
ann.annotation_type = AnnotationType::Minimized;
} else if lo.line != hi.line {
ann.annotation_type = AnnotationType::Multiline {
depth: 1,
line_start: lo.line,
line_end: hi.line,
};
multiline_annotations.push((lo.file.clone(), ann.clone()));
};

if !ann.is_multiline() {
add_annotation_to_file(&mut output,
lo.file,
lo.line,
ann);
}
}
}

// Find overlapping multiline annotations, put them at different depths
multiline_annotations.sort_by(|a, b| a.1.start_col.cmp(&b.1.start_col));
for item in multiline_annotations.clone() {
let ann = item.1;
for item in multiline_annotations.iter_mut() {
let ref mut a = item.1;
let ann_depth = ann.annotation_type.depth();
let a_depth = a.annotation_type.depth();
// Move all other multiline annotations overlapping with this one
// one level to the right.
if &ann != a && ann.end_col > a.start_col && ann_depth == a_depth {
a.annotation_type.increase_depth();
} else {
break
}
}
}

let mut max_depth = 0; // max overlapping multiline spans
for (file, ann) in multiline_annotations {
if let AnnotationType::Multiline {line_start, line_end, depth} = ann.annotation_type {
if depth > max_depth {
max_depth = depth;
}
add_annotation_to_file(&mut output, file.clone(), line_start, ann.as_start());
for line in line_start + 1..line_end {
add_annotation_to_file(&mut output, file.clone(), line, ann.as_line());
}
add_annotation_to_file(&mut output, file, line_end, ann.as_end());
}
}
for file_vec in output.iter_mut() {
file_vec.multiline_depth = max_depth;
}
output
}

fn render_source_line(&self,
buffer: &mut StyledBuffer,
file: Rc<FileMap>,
line: &Line,
width_offset: usize) {
width_offset: usize,
multiline_depth: usize) {
let source_string = file.get_line(line.line_index - 1)
.unwrap_or("");

let line_offset = buffer.num_lines();
let code_offset = if multiline_depth == 0 {
width_offset
} else {
width_offset + multiline_depth + 1
};

// First create the source line we will highlight.
buffer.puts(line_offset, width_offset, &source_string, Style::Quotation);
buffer.puts(line_offset, code_offset, &source_string, Style::Quotation);
buffer.puts(line_offset,
0,
&(line.line_index.to_string()),
Expand Down Expand Up @@ -228,39 +287,74 @@ impl EmitterWriter {
let mut annotations = line.annotations.clone();
annotations.sort();

let mut only_source_shown = true;
// Next, create the highlight line.
for annotation in &annotations {
let (underline, style) = if annotation.is_primary {
('^', Style::UnderlinePrimary)
} else {
('-', Style::UnderlineSecondary)
};
if let AnnotationType::MultilineLine(depth) = annotation.annotation_type {
draw_col_separator_no_space_with_style(buffer,
line_offset,
width_offset + depth - 1,
style);
break;
}
for p in annotation.start_col..annotation.end_col {
if annotation.is_primary {
buffer.putc(line_offset + 1,
width_offset + p,
'^',
Style::UnderlinePrimary);
if !annotation.is_minimized {
buffer.set_style(line_offset, width_offset + p, Style::UnderlinePrimary);
}
} else {
buffer.putc(line_offset + 1,
code_offset + p,
underline,
style);
if !annotation.is_minimized() {
buffer.set_style(line_offset, code_offset + p, style);
}
}
// For multiline spans, add enclosing line
if let AnnotationType::MultilineStart(depth) = annotation.annotation_type {
for p in width_offset + depth..code_offset + annotation.end_col - 1 {
buffer.putc(line_offset + 1,
width_offset + p,
'-',
Style::UnderlineSecondary);
if !annotation.is_minimized {
buffer.set_style(line_offset, width_offset + p, Style::UnderlineSecondary);
}
p,
'_',
style);
}
}
if let AnnotationType::MultilineEnd(depth) = annotation.annotation_type {
draw_col_separator_no_space_with_style(buffer,
line_offset,
width_offset + depth - 1,
style);
draw_col_separator_no_space_with_style(buffer,
line_offset + 1,
width_offset + depth - 1,
style);
draw_range(buffer,
'_',
line_offset + 1,
width_offset + depth,
code_offset + annotation.end_col - 1,
style);
}
only_source_shown = false;
}
if !only_source_shown {
draw_col_separator(buffer, line_offset + 1, width_offset - 2);
}
draw_col_separator(buffer, line_offset + 1, width_offset - 2);

// Now we are going to write labels in. To start, we'll exclude
// the annotations with no labels.
let (labeled_annotations, unlabeled_annotations): (Vec<_>, _) = annotations.into_iter()
.partition(|a| a.label.is_some());
let (labeled_annotations, unlabeled_annotations): (Vec<_>, _) = annotations
.clone().into_iter().partition(|a| a.label.is_some());

// If there are no annotations that need text, we're done.
if labeled_annotations.is_empty() {
return;
}

let multiline_annotations = annotations.iter()
.filter(|a| a.is_multiline()).collect::<Vec<_>>();

// Now add the text labels. We try, when possible, to stick the rightmost
// annotation at the end of the highlight line:
//
Expand Down Expand Up @@ -305,11 +399,11 @@ impl EmitterWriter {
// append the label afterwards; we keep it in a separate
// string
let highlight_label: String = format!(" {}", last.label.as_ref().unwrap());
if last.is_primary {
buffer.append(line_offset + 1, &highlight_label, Style::LabelPrimary);
buffer.append(line_offset + 1, &highlight_label, if last.is_primary {
Style::LabelPrimary
} else {
buffer.append(line_offset + 1, &highlight_label, Style::LabelSecondary);
}
Style::LabelSecondary
});
labeled_annotations = previous;
}
}
Expand All @@ -330,28 +424,35 @@ impl EmitterWriter {
// For each blank line, draw a `|` at our column. The
// text ought to be long enough for this.
for index in 2..blank_lines {
if annotation.is_primary {
buffer.putc(line_offset + index,
width_offset + annotation.start_col,
'|',
Style::UnderlinePrimary);
let style = if annotation.is_primary {
Style::UnderlinePrimary
} else {
buffer.putc(line_offset + index,
width_offset + annotation.start_col,
'|',
Style::UnderlineSecondary);
Style::UnderlineSecondary
};
draw_col_separator_no_space_with_style(buffer,
line_offset + index,
code_offset + annotation.start_col,
style);
for a in multiline_annotations.iter() {
if let AnnotationType::MultilineLine(depth) = a.annotation_type {
draw_col_separator_no_space_with_style(buffer,
line_offset + index,
width_offset + depth - 1,
style);
}
}
draw_col_separator(buffer, line_offset + index, width_offset - 2);

}

if annotation.is_primary {
buffer.puts(line_offset + blank_lines,
width_offset + annotation.start_col,
code_offset + annotation.start_col,
annotation.label.as_ref().unwrap(),
Style::LabelPrimary);
} else {
buffer.puts(line_offset + blank_lines,
width_offset + annotation.start_col,
code_offset + annotation.start_col,
annotation.label.as_ref().unwrap(),
Style::LabelSecondary);
}
Expand Down Expand Up @@ -577,7 +678,8 @@ impl EmitterWriter {
self.render_source_line(&mut buffer,
annotated_file.file.clone(),
&annotated_file.lines[line_idx],
3 + max_line_num_len);
3 + max_line_num_len,
annotated_file.multiline_depth);

// check to see if we need to print out or elide lines that come between
// this annotated line and the next one
Expand Down Expand Up @@ -729,7 +831,19 @@ fn draw_col_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
}

fn draw_col_separator_no_space(buffer: &mut StyledBuffer, line: usize, col: usize) {
buffer.puts(line, col, "|", Style::LineNumber);
draw_col_separator_no_space_with_style(buffer, line, col, Style::LineNumber);
}

fn draw_col_separator_no_space_with_style(buffer: &mut StyledBuffer, line: usize,
col: usize, style: Style) {
buffer.putc(line, col, '|', style);
}

fn draw_range(buffer: &mut StyledBuffer, symbol: char, line: usize,
col_from: usize, col_to: usize, style: Style) {
for col in col_from..col_to {
buffer.putc(line, col, symbol, style);
}
}

fn draw_note_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
Expand Down
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