Make file names in error messages links to that file.

Cargo.lock

@@ -2511,6 +2511,17 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "hostname"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3c731c3e10504cc8ed35cfe2f1db4c9274c3d35fa486e3b31df46f068ef3e867"
+dependencies = [
+ "libc",
+ "match_cfg",
+ "winapi",
+]
+
 [[package]]
 name = "html-checker"
 version = "0.1.0"
@@ -3066,6 +3077,12 @@ dependencies = [
  "tendril",
 ]
 
+[[package]]
+name = "match_cfg"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ffbee8634e0d45d258acb448e7eaab3fce7a0a467395d4d9f228e3c1f01fb2e4"
+
 [[package]]
 name = "matchers"
 version = "0.1.0"
@@ -5295,6 +5312,7 @@ name = "rustc_span"
 version = "0.0.0"
 dependencies = [
  "cfg-if",
+ "hostname",
  "indexmap",
  "md-5",
  "rustc_arena",

compiler/rustc_builtin_macros/src/test.rs

@@ -400,7 +400,7 @@ fn get_location_info(cx: &ExtCtxt<'_>, item: &ast::Item) -> (Symbol, usize, usiz
         cx.sess.source_map().span_to_location_info(span);
 
     let file_name = match source_file {
-        Some(sf) => sf.name.display(FileNameDisplayPreference::Remapped).to_string(),
+        Some(sf) => sf.name.display(FileNameDisplayPreference::Remapped, false).to_string(),
         None => "no-location".to_string(),
     };
 

compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs

@@ -159,7 +159,7 @@ impl AnnotateSnippetEmitterWriter {
             }
             // owned: line source, line index, annotations
             type Owned = (String, usize, Vec<crate::snippet::Annotation>);
-            let filename = source_map.filename_for_diagnostics(&primary_lo.file.name);
+            let filename = source_map.filename_for_diagnostics(&primary_lo.file.name, false);
             let origin = filename.to_string_lossy();
             let annotated_files: Vec<Owned> = annotated_files
                 .into_iter()

compiler/rustc_errors/src/emitter.rs

@@ -1456,7 +1456,10 @@ impl EmitterWriter {
                                 line_idx,
                                 &format!(
                                     "{}:{}:{}",
-                                    sm.filename_for_diagnostics(&annotated_file.file.name),
+                                    sm.filename_for_diagnostics(
+                                        &annotated_file.file.name,
+                                        self.terminal_url == TerminalUrl::Yes
+                                    ),
                                     sm.doctest_offset_line(
                                         &annotated_file.file.name,
                                         line.line_index
@@ -1512,7 +1515,10 @@ impl EmitterWriter {
                         buffer_msg_line_offset,
                         &format!(
                             "{}:{}:{}",
-                            sm.filename_for_diagnostics(&loc.file.name),
+                            sm.filename_for_diagnostics(
+                                &loc.file.name,
+                                self.terminal_url == TerminalUrl::Yes
+                            ),
                             sm.doctest_offset_line(&loc.file.name, loc.line),
                             loc.col.0 + 1,
                         ),
@@ -1526,7 +1532,10 @@ impl EmitterWriter {
                         0,
                         &format!(
                             "{}:{}:{}: ",
-                            sm.filename_for_diagnostics(&loc.file.name),
+                            sm.filename_for_diagnostics(
+                                &loc.file.name,
+                                self.terminal_url == TerminalUrl::Yes
+                            ),
                             sm.doctest_offset_line(&loc.file.name, loc.line),
                             loc.col.0 + 1,
                         ),
@@ -1554,12 +1563,21 @@ impl EmitterWriter {
                     };
                     format!(
                         "{}:{}{}",
-                        sm.filename_for_diagnostics(&annotated_file.file.name),
+                        sm.filename_for_diagnostics(
+                            &annotated_file.file.name,
+                            self.terminal_url == TerminalUrl::Yes
+                        ),
                         sm.doctest_offset_line(&annotated_file.file.name, first_line.line_index),
                         col
                     )
                 } else {
-                    format!("{}", sm.filename_for_diagnostics(&annotated_file.file.name))
+                    format!(
+                        "{}",
+                        sm.filename_for_diagnostics(
+                            &annotated_file.file.name,
+                            self.terminal_url == TerminalUrl::Yes
+                        )
+                    )
                 };
                 buffer.append(buffer_msg_line_offset + 1, &loc, Style::LineAndColumn);
                 for _ in 0..max_line_num_len {
@@ -1815,7 +1833,10 @@ impl EmitterWriter {
                 if loc.file.name != sm.span_to_filename(span) && loc.file.name.is_real() {
                     let arrow = "--> ";
                     buffer.puts(row_num - 1, 0, arrow, Style::LineNumber);
-                    let filename = sm.filename_for_diagnostics(&loc.file.name);
+                    let filename = sm.filename_for_diagnostics(
+                        &loc.file.name,
+                        self.terminal_url == TerminalUrl::Yes,
+                    );
                     let offset = sm.doctest_offset_line(&loc.file.name, loc.line);
                     let message = format!("{}:{}:{}", filename, offset, loc.col.0 + 1);
                     if row_num == 2 {

compiler/rustc_errors/src/json.rs

@@ -475,7 +475,7 @@ impl DiagnosticSpan {
         });
 
         DiagnosticSpan {
-            file_name: je.sm.filename_for_diagnostics(&start.file.name).to_string(),
+            file_name: je.sm.filename_for_diagnostics(&start.file.name, false).to_string(),
             byte_start: start.file.original_relative_byte_pos(span.lo()).0,
             byte_end: start.file.original_relative_byte_pos(span.hi()).0,
             line_start: start.line,

compiler/rustc_expand/src/base.rs

@@ -1202,7 +1202,10 @@ pub fn resolve_path(
             other => {
                 return Err(errors::ResolveRelativePath {
                     span,
-                    path: parse_sess.source_map().filename_for_diagnostics(&other).to_string(),
+                    path: parse_sess
+                        .source_map()
+                        .filename_for_diagnostics(&other, false)
+                        .to_string(),
                 }
                 .into_diagnostic(&parse_sess.span_diagnostic));
             }

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -1760,7 +1760,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                                 let pos = sm.lookup_char_pos(self.tcx.def_span(*def_id).lo());
                                 format!(
                                     " (opaque type at <{}:{}:{}>)",
-                                    sm.filename_for_diagnostics(&pos.file.name),
+                                    sm.filename_for_diagnostics(&pos.file.name, false),
                                     pos.line,
                                     pos.col.to_usize() + 1,
                                 )
@@ -1772,7 +1772,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                                 let pos = sm.lookup_char_pos(self.tcx.def_span(proj.def_id).lo());
                                 format!(
                                     " (trait associated opaque type at <{}:{}:{}>)",
-                                    sm.filename_for_diagnostics(&pos.file.name),
+                                    sm.filename_for_diagnostics(&pos.file.name, false),
                                     pos.line,
                                     pos.col.to_usize() + 1,
                                 )

compiler/rustc_parse/src/lib.rs

@@ -192,7 +192,7 @@ pub fn maybe_file_to_stream(
     let src = source_file.src.as_ref().unwrap_or_else(|| {
         sess.span_diagnostic.bug(&format!(
             "cannot lex `source_file` without source: {}",
-            sess.source_map().filename_for_diagnostics(&source_file.name)
+            sess.source_map().filename_for_diagnostics(&source_file.name, false)
         ));
     });
 

compiler/rustc_span/Cargo.toml

@@ -19,3 +19,4 @@ sha1 = "0.10.0"
 sha2 = "0.10.1"
 md5 = { package = "md-5", version = "0.10.0" }
 indexmap = { version = "1.9.3" }
+hostname = "0.3.1"

compiler/rustc_span/src/lib.rs

@@ -323,14 +323,61 @@ pub enum FileNameDisplayPreference {
 pub struct FileNameDisplay<'a> {
     inner: &'a FileName,
     display_pref: FileNameDisplayPreference,
+    link: bool,
+}
+
+fn resolve_file_uri(path: &Path) -> Option<String> {
+    fn uri_encode(str: &str) -> String {
+        let mut res = String::with_capacity(str.len());
+
+        for &x in str.as_bytes() {
+            // ascii characters are encoded directly.
+            // ':' and ';' are used as control sequences and so can't be used.
+            if (32..127).contains(&x) && x != ':' as u8 && x != ';' as u8 {
+                res.push(x as char)
+            } else {
+                res.push('%');
+                res.push_str(&format!("{x:02x}"));
+            }
+        }
+
+        res
+    }
+
+    // Absolute paths are never excepted.
+    let canonical_path = path.canonicalize().ok()?;
+    // But we can get away without a hostname.
+    let hostname = hostname::get().unwrap_or_default();
+
+    let canonical_path = uri_encode(canonical_path.to_str()?);
+    // Sometimes the canonical path starts with a slash otherwise we need to add one.
+    let separator = if canonical_path.starts_with("/") { "" } else { "/" };
+    let hostname = uri_encode(hostname.to_str()?);
+
+    Some(format!("file://{hostname}{separator}{canonical_path}"))
 }
 
 impl fmt::Display for FileNameDisplay<'_> {
     fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         use FileName::*;
         match *self.inner {
             Real(ref name) => {
-                write!(fmt, "{}", name.to_string_lossy(self.display_pref))
+                let file_uri = if self.link && let Some(path) = name.local_path() {
+                    resolve_file_uri(path)
+                } else {
+                    None
+                };
+
+                if let Some(file_uri) = file_uri {
+                    write!(
+                        fmt,
+                        "\x1b]8;;{}\x07{}\x1b]8;;\x07",
+                        file_uri,
+                        name.to_string_lossy(self.display_pref)
+                    )
+                } else {
+                    write!(fmt, "{}", name.to_string_lossy(self.display_pref))
+                }
             }
             QuoteExpansion(_) => write!(fmt, "<quote expansion>"),
             MacroExpansion(_) => write!(fmt, "<macro expansion>"),
@@ -372,17 +419,25 @@ impl FileName {
     }
 
     pub fn prefer_remapped(&self) -> FileNameDisplay<'_> {
-        FileNameDisplay { inner: self, display_pref: FileNameDisplayPreference::Remapped }
+        FileNameDisplay {
+            inner: self,
+            display_pref: FileNameDisplayPreference::Remapped,
+            link: false,
+        }
     }
 
     /// This may include transient local filesystem information.
     /// Must not be embedded in build outputs.
     pub fn prefer_local(&self) -> FileNameDisplay<'_> {
-        FileNameDisplay { inner: self, display_pref: FileNameDisplayPreference::Local }
+        FileNameDisplay { inner: self, display_pref: FileNameDisplayPreference::Local, link: false }
     }
 
-    pub fn display(&self, display_pref: FileNameDisplayPreference) -> FileNameDisplay<'_> {
-        FileNameDisplay { inner: self, display_pref }
+    pub fn display(
+        &self,
+        display_pref: FileNameDisplayPreference,
+        link: bool,
+    ) -> FileNameDisplay<'_> {
+        FileNameDisplay { inner: self, display_pref, link }
     }
 
     pub fn macro_expansion_source_code(src: &str) -> FileName {

compiler/rustc_span/src/source_map.rs

@@ -451,7 +451,7 @@ impl SourceMap {
         let (source_file, lo_line, lo_col, hi_line, hi_col) = self.span_to_location_info(sp);
 
         let file_name = match source_file {
-            Some(sf) => sf.name.display(filename_display_pref).to_string(),
+            Some(sf) => sf.name.display(filename_display_pref, false).to_string(),
             None => return "no-location".to_string(),
         };
 
@@ -502,7 +502,7 @@ impl SourceMap {
 
         format!(
             "{}:+{}:{}: +{}:{}",
-            lo.file.name.display(FileNameDisplayPreference::Remapped),
+            lo.file.name.display(FileNameDisplayPreference::Remapped, false),
             lo_line,
             lo.col.to_usize() + 1,
             hi_line,
@@ -521,8 +521,12 @@ impl SourceMap {
         self.lookup_char_pos(sp.lo()).file.name.clone()
     }
 
-    pub fn filename_for_diagnostics<'a>(&self, filename: &'a FileName) -> FileNameDisplay<'a> {
-        filename.display(self.path_mapping.filename_display_for_diagnostics)
+    pub fn filename_for_diagnostics<'a>(
+        &self,
+        filename: &'a FileName,
+        link: bool,
+    ) -> FileNameDisplay<'a> {
+        filename.display(self.path_mapping.filename_display_for_diagnostics, link)
     }
 
     pub fn is_multiline(&self, sp: Span) -> bool {

src/tools/tidy/src/deps.rs

@@ -141,6 +141,7 @@ const PERMITTED_RUSTC_DEPENDENCIES: &[&str] = &[
     "gsgdt",
     "hashbrown",
     "hermit-abi",
+    "hostname",
     "icu_list",
     "icu_locid",
     "icu_provider",
@@ -161,6 +162,7 @@ const PERMITTED_RUSTC_DEPENDENCIES: &[&str] = &[
     "lock_api",
     "log",
     "matchers",
+    "match_cfg",
     "md-5",
     "measureme",
     "memchr",

tests/ui/diagnostic-flags/terminal_urls.stderr

@@ -1,7 +1,7 @@
 error[]8;;https://doc.rust-lang.org/error_codes/E0308.htmlE0308]8;;]: mismatched types
-  --> $DIR/terminal_urls.rs:3:9
+  --> ]8;;file://$DIR/terminal_urls.rs$DIR/terminal_urls.rs]8;;:3:9
    |
-LL |     let () = 4;
+   |     let () = 4;
    |         ^^   - this expression has type `{integer}`
    |         |
    |         expected integer, found `()`