Auto merge of #126804 - estebank:short-error-primary-label, r=davidtwco

On short error format, append primary span label to message

The `error-format=short` output only displays the path, error code and main error message all in the same line. We now add the primary span label as well after the error message, to provide more context.

compiler/rustc_errors/src/emitter.rs

@@ -1346,10 +1346,11 @@ impl HumanEmitter {
                 buffer.append(0, ": ", header_style);
                 label_width += 2;
             }
+            let mut line = 0;
             for (text, _) in msgs.iter() {
                 let text = self.translate_message(text, args).map_err(Report::new).unwrap();
                 // Account for newlines to align output to its label.
-                for (line, text) in normalize_whitespace(&text).lines().enumerate() {
+                for text in normalize_whitespace(&text).lines() {
                     buffer.append(
                         line,
                         &format!(
@@ -1359,6 +1360,25 @@ impl HumanEmitter {
                         ),
                         header_style,
                     );
+                    line += 1;
+                }
+            }
+            if self.short_message {
+                let labels = msp
+                    .span_labels()
+                    .into_iter()
+                    .filter_map(|label| match label.label {
+                        Some(msg) if label.is_primary => {
+                            let text = self.translate_message(&msg, args).ok()?;
+                            if !text.trim().is_empty() { Some(text.to_string()) } else { None }
+                        }
+                        _ => None,
+                    })
+                    .collect::<Vec<_>>()
+                    .join(", ");
+                if !labels.is_empty() {
+                    buffer.append(line, ": ", Style::NoStyle);
+                    buffer.append(line, &labels, Style::NoStyle);
                 }
             }
         }