Shorten trimmed display of closures

When `with_forced_trimmed_paths` is used, only print filename and start
of the closure's span, to reduce their verbosity.

2 files changed, 18 insertions, 4 deletions

diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs
index 5525eb5331c..2181c090027 100644
--- a/compiler/rustc_span/src/lib.rs
+++ b/compiler/rustc_span/src/lib.rs
@@ -259,6 +259,10 @@ impl RealFileName {
             FileNameDisplayPreference::Remapped => {
                 self.remapped_path_if_available().to_string_lossy()
             }
+            FileNameDisplayPreference::Short => self
+                .local_path_if_available()
+                .file_name()
+                .map_or_else(|| "".into(), |f| f.to_string_lossy()),
         }
     }
 }
@@ -302,6 +306,9 @@ pub enum FileNameDisplayPreference {
     /// Display the path before the application of rewrite rules provided via `--remap-path-prefix`.
     /// This is appropriate for use in user-facing output (such as diagnostics).
     Local,
+    /// Display only the filename, as a way to reduce the verbosity of the output.
+    /// This is appropriate for use in user-facing output (such as diagnostics).
+    Short,
 }
 
 pub struct FileNameDisplay<'a> {
diff --git a/compiler/rustc_span/src/source_map.rs b/compiler/rustc_span/src/source_map.rs
index fb3e4a6c083..d9c87ac0ba8 100644
--- a/compiler/rustc_span/src/source_map.rs
+++ b/compiler/rustc_span/src/source_map.rs
@@ -438,7 +438,11 @@ impl SourceMap {
         }
     }
 
-    fn span_to_string(&self, sp: Span, filename_display_pref: FileNameDisplayPreference) -> String {
+    pub fn span_to_string(
+        &self,
+        sp: Span,
+        filename_display_pref: FileNameDisplayPreference,
+    ) -> String {
         if self.files.borrow().source_files.is_empty() || sp.is_dummy() {
             return "no-location".to_string();
         }
@@ -446,12 +450,15 @@ impl SourceMap {
         let lo = self.lookup_char_pos(sp.lo());
         let hi = self.lookup_char_pos(sp.hi());
         format!(
-            "{}:{}:{}: {}:{}",
+            "{}:{}:{}{}",
             lo.file.name.display(filename_display_pref),
             lo.line,
             lo.col.to_usize() + 1,
-            hi.line,
-            hi.col.to_usize() + 1,
+            if let FileNameDisplayPreference::Short = filename_display_pref {
+                String::new()
+            } else {
+                format!(": {}:{}", hi.line, hi.col.to_usize() + 1)
+            }
         )
     }