Mention filename in suggestion when it differs from primary span

[rust.git] / compiler / rustc_errors / src / emitter.rs

diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 5dd743e8d00236b93dfd4e79600a65af700c77ce..e9e7065ec03cc744b90b8bda4a96c903926b8ec2 100644 (file)
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -1261,16 +1261,23 @@ fn get_multispan_max_line_num(&mut self, msp: &MultiSpan) -> usize {
             return 0;
         };
 
+        let will_be_emitted = |span: Span| {
+            !span.is_dummy() && {
+                let file = sm.lookup_source_file(span.hi());
+                sm.ensure_source_file_source_present(file)
+            }
+        };
+
         let mut max = 0;
         for primary_span in msp.primary_spans() {
-            if !primary_span.is_dummy() {
+            if will_be_emitted(*primary_span) {
                 let hi = sm.lookup_char_pos(primary_span.hi());
                 max = (hi.line).max(max);
             }
         }
         if !self.short_message {
             for span_label in msp.span_labels() {
-                if !span_label.span.is_dummy() {
+                if will_be_emitted(span_label.span) {
                     let hi = sm.lookup_char_pos(span_label.span.hi());
                     max = (hi.line).max(max);
                 }
@@ -1708,6 +1715,7 @@ fn emit_message_default(
 
     fn emit_suggestion_default(
         &mut self,
+        span: &MultiSpan,
         suggestion: &CodeSuggestion,
         args: &FluentArgs<'_>,
         level: &Level,
@@ -1759,6 +1767,30 @@ enum DisplaySuggestion {
                 None,
             }
 
+            if let Some(span) = span.primary_span() {
+                // Compare the primary span of the diagnostic with the span of the suggestion
+                // being emitted.  If they belong to the same file, we don't *need* to show the
+                // file name, saving in verbosity, but if it *isn't* we do need it, otherwise we're
+                // telling users to make a change but not clarifying *where*.
+                let loc = sm.lookup_char_pos(parts[0].span.lo());
+                if loc.file.name != sm.span_to_filename(span) && loc.file.name.is_real() {
+                    buffer.puts(row_num - 1, 0, "--> ", Style::LineNumber);
+                    buffer.append(
+                        row_num - 1,
+                        &format!(
+                            "{}:{}:{}",
+                            sm.filename_for_diagnostics(&loc.file.name),
+                            sm.doctest_offset_line(&loc.file.name, loc.line),
+                            loc.col.0 + 1,
+                        ),
+                        Style::LineAndColumn,
+                    );
+                    for _ in 0..max_line_num_len {
+                        buffer.prepend(row_num - 1, " ", Style::NoStyle);
+                    }
+                    row_num += 1;
+                }
+            }
             let show_code_change = if has_deletion && !is_multiline {
                 DisplaySuggestion::Diff
             } else if (parts.len() != 1 || parts[0].snippet.trim() != complete.trim())
@@ -1780,7 +1812,7 @@ enum DisplaySuggestion {
             assert!(!file_lines.lines.is_empty() || parts[0].span.is_dummy());
 
             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);
+            draw_col_separator_no_space(&mut buffer, row_num - 1, max_line_num_len + 1);
             let mut lines = complete.lines();
             if lines.clone().next().is_none() {
                 // Account for a suggestion to completely remove a line(s) with whitespace (#94192).
@@ -2039,9 +2071,13 @@ fn emit_messages_default(
                             ) {
                                 panic!("failed to emit error: {}", e);
                             }
-                        } else if let Err(e) =
-                            self.emit_suggestion_default(sugg, args, &Level::Help, max_line_num_len)
-                        {
+                        } else if let Err(e) = self.emit_suggestion_default(
+                            span,
+                            sugg,
+                            args,
+                            &Level::Help,
+                            max_line_num_len,
+                        ) {
                             panic!("failed to emit error: {}", e);
                         };
                     }