Auto merge of #33688 - jonathandturner:fix_old_school, r=nikomatsakis

Fix for old school error issues, improvements to new school

This PR:
* Fixes some old school error issues, specifically #33559, #33543, #33366
* Improves wording borrowck errors with match patterns
* De-emphasize multi-line spans, so we don't color the single source character when we're trying to say "span starts here"
* Rollup of #33392 (which should help fix #33390)

r? @nikomatsakis

3 files changed, 54 insertions, 10 deletions

diff --git a/src/libsyntax/errors/emitter.rs b/src/libsyntax/errors/emitter.rs
index e7007fb0568..8d0c93f21b2 100644
--- a/src/libsyntax/errors/emitter.rs
+++ b/src/libsyntax/errors/emitter.rs
@@ -367,7 +367,8 @@ impl EmitterWriter {
             let mut output_vec = vec![];
 
             for span_label in msp.span_labels() {
-                let mut snippet_data = snippet_data.clone();
+                let mut snippet_data = SnippetData::new(self.cm.clone(),
+                                                        Some(span_label.span));
 
                 snippet_data.push(span_label.span,
                                   span_label.is_primary,
@@ -524,6 +525,13 @@ impl Destination {
             }
             Style::Quotation => {
             }
+            Style::OldSkoolNote => {
+                self.start_attr(term::Attr::Bold)?;
+                self.start_attr(term::Attr::ForegroundColor(term::color::BRIGHT_GREEN))?;
+            }
+            Style::OldSkoolNoteText => {
+                self.start_attr(term::Attr::Bold)?;
+            }
             Style::UnderlinePrimary | Style::LabelPrimary => {
                 self.start_attr(term::Attr::Bold)?;
                 self.start_attr(term::Attr::ForegroundColor(lvl.color()))?;
diff --git a/src/libsyntax/errors/mod.rs b/src/libsyntax/errors/mod.rs
index 2ca61ba76d4..f06672fe111 100644
--- a/src/libsyntax/errors/mod.rs
+++ b/src/libsyntax/errors/mod.rs
@@ -699,13 +699,13 @@ pub fn expect<T, M>(diag: &Handler, opt: Option<T>, msg: M) -> T where
 ///
 /// FIXME(#33240)
 #[cfg(not(test))]
-fn check_old_skool() -> bool {
+pub fn check_old_skool() -> bool {
     use std::env;
     env::var("RUST_NEW_ERROR_FORMAT").is_err()
 }
 
 /// For unit tests, use the new format.
 #[cfg(test)]
-fn check_old_skool() -> bool {
+pub fn check_old_skool() -> bool {
     false
 }
diff --git a/src/libsyntax/errors/snippet/mod.rs b/src/libsyntax/errors/snippet/mod.rs
index 092effbb2f6..188e676e7df 100644
--- a/src/libsyntax/errors/snippet/mod.rs
+++ b/src/libsyntax/errors/snippet/mod.rs
@@ -58,6 +58,9 @@ struct Annotation {
     /// Is this annotation derived from primary span
     is_primary: bool,
 
+    /// Is this a large span minimized down to a smaller span
+    is_minimized: bool,
+
     /// Optional label to display adjacent to the annotation.
     label: Option<String>,
 }
@@ -90,6 +93,8 @@ pub enum Style {
     UnderlineSecondary,
     LabelPrimary,
     LabelSecondary,
+    OldSkoolNoteText,
+    OldSkoolNote,
     NoStyle,
 }
 
@@ -382,10 +387,10 @@ impl FileInfo {
         // Basically, although this loses information, multi-line spans just
         // never look good.
 
-        let (line, start_col, mut end_col) = if lines.len() == 1 {
-            (lines[0].line_index, lines[0].start_col, lines[0].end_col)
+        let (line, start_col, mut end_col, is_minimized) = if lines.len() == 1 {
+            (lines[0].line_index, lines[0].start_col, lines[0].end_col, false)
         } else {
-            (lines[0].line_index, lines[0].start_col, CharPos(lines[0].start_col.0 + 1))
+            (lines[0].line_index, lines[0].start_col, CharPos(lines[0].start_col.0 + 1), true)
         };
 
         // Watch out for "empty spans". If we get a span like 6..6, we
@@ -401,6 +406,7 @@ impl FileInfo {
         self.lines[index].push_annotation(start_col,
                                           end_col,
                                           is_primary,
+                                          is_minimized,
                                           label);
     }
 
@@ -497,6 +503,30 @@ impl FileInfo {
                     match self.primary_span {
                         Some(span) => {
                             let lo = codemap.lookup_char_pos(span.lo);
+                            let hi = codemap.lookup_char_pos(span.hi);
+                            //Before each secondary line in old skool-mode, print the label
+                            //as an old-style note
+                            if !line.annotations[0].is_primary {
+                                if let Some(ann) = line.annotations[0].label.clone() {
+                                    output.push(RenderedLine {
+                                        text: vec![StyledString {
+                                            text: lo.file.name.clone(),
+                                            style: Style::FileNameStyle,
+                                        }, StyledString {
+                                            text: format!(":{}:{}: {}:{} ", lo.line, lo.col.0 + 1,
+                                                hi.line, hi.col.0+1),
+                                            style: Style::LineAndColumn,
+                                        }, StyledString {
+                                            text: format!("note: "),
+                                            style: Style::OldSkoolNote,
+                                        }, StyledString {
+                                            text: format!("{}", ann),
+                                            style: Style::OldSkoolNoteText,
+                                        }],
+                                        kind: RenderedLineKind::Annotations,
+                                    });
+                                }
+                            }
                             rendered_lines[0].text.insert(0, StyledString {
                                 text: format!(":{} ", lo.line),
                                 style: Style::LineAndColumn,
@@ -598,7 +628,7 @@ impl FileInfo {
                             if annotation.is_primary {
                                 Style::UnderlinePrimary
                             } else {
-                                Style::UnderlineSecondary
+                                Style::OldSkoolNote
                             });
                     }
                     else {
@@ -606,7 +636,7 @@ impl FileInfo {
                             if annotation.is_primary {
                                 Style::UnderlinePrimary
                             } else {
-                                Style::UnderlineSecondary
+                                Style::OldSkoolNote
                             });
                     }
                 }
@@ -615,10 +645,14 @@ impl FileInfo {
                 for p in annotation.start_col .. annotation.end_col {
                     if annotation.is_primary {
                         styled_buffer.putc(1, p, '^', Style::UnderlinePrimary);
-                        styled_buffer.set_style(0, p, Style::UnderlinePrimary);
+                        if !annotation.is_minimized {
+                            styled_buffer.set_style(0, p, Style::UnderlinePrimary);
+                        }
                     } else {
                         styled_buffer.putc(1, p, '-', Style::UnderlineSecondary);
-                        styled_buffer.set_style(0, p, Style::UnderlineSecondary);
+                        if !annotation.is_minimized {
+                            styled_buffer.set_style(0, p, Style::UnderlineSecondary);
+                        }
                     }
                 }
             }
@@ -819,11 +853,13 @@ impl Line {
                        start: CharPos,
                        end: CharPos,
                        is_primary: bool,
+                       is_minimized: bool,
                        label: Option<String>) {
         self.annotations.push(Annotation {
             start_col: start.0,
             end_col: end.0,
             is_primary: is_primary,
+            is_minimized: is_minimized,
             label: label,
         });
     }