Introduce -Zterminal-urls to use OSC8 for error codes

Terminals supporting the OSC8 Hyperlink Extension can support inline
anchors where the text is user defineable but clicking on it opens a
browser to a specified URLs, just like `<a href="URL">` does in HTML.

https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda

compiler/rustc_errors/src/emitter.rs

@@ -18,7 +18,7 @@ use crate::translation::{to_fluent_args, Translate};
 use crate::{
     diagnostic::DiagnosticLocation, CodeSuggestion, Diagnostic, DiagnosticId, DiagnosticMessage,
     FluentBundle, Handler, LazyFallbackBundle, Level, MultiSpan, SubDiagnostic,
-    SubstitutionHighlight, SuggestionStyle,
+    SubstitutionHighlight, SuggestionStyle, TerminalUrl,
 };
 use rustc_lint_defs::pluralize;
 
@@ -66,6 +66,7 @@ impl HumanReadableErrorType {
         diagnostic_width: Option<usize>,
         macro_backtrace: bool,
         track_diagnostics: bool,
+        terminal_url: TerminalUrl,
     ) -> EmitterWriter {
         let (short, color_config) = self.unzip();
         let color = color_config.suggests_using_colors();
@@ -80,6 +81,7 @@ impl HumanReadableErrorType {
             diagnostic_width,
             macro_backtrace,
             track_diagnostics,
+            terminal_url,
         )
     }
 }
@@ -652,6 +654,7 @@ pub struct EmitterWriter {
 
     macro_backtrace: bool,
     track_diagnostics: bool,
+    terminal_url: TerminalUrl,
 }
 
 #[derive(Debug)]
@@ -672,6 +675,7 @@ impl EmitterWriter {
         diagnostic_width: Option<usize>,
         macro_backtrace: bool,
         track_diagnostics: bool,
+        terminal_url: TerminalUrl,
     ) -> EmitterWriter {
         let dst = Destination::from_stderr(color_config);
         EmitterWriter {
@@ -685,6 +689,7 @@ impl EmitterWriter {
             diagnostic_width,
             macro_backtrace,
             track_diagnostics,
+            terminal_url,
         }
     }
 
@@ -699,6 +704,7 @@ impl EmitterWriter {
         diagnostic_width: Option<usize>,
         macro_backtrace: bool,
         track_diagnostics: bool,
+        terminal_url: TerminalUrl,
     ) -> EmitterWriter {
         EmitterWriter {
             dst: Raw(dst, colored),
@@ -711,6 +717,7 @@ impl EmitterWriter {
             diagnostic_width,
             macro_backtrace,
             track_diagnostics,
+            terminal_url,
         }
     }
 
@@ -1378,7 +1385,13 @@ impl EmitterWriter {
             // only render error codes, not lint codes
             if let Some(DiagnosticId::Error(ref code)) = *code {
                 buffer.append(0, "[", Style::Level(*level));
-                buffer.append(0, code, Style::Level(*level));
+                let code = if let TerminalUrl::Yes = self.terminal_url {
+                    let path = "https://doc.rust-lang.org/error_codes";
+                    format!("\x1b]8;;{path}/{code}.html\x07{code}\x1b]8;;\x07")
+                } else {
+                    code.clone()
+                };
+                buffer.append(0, &code, Style::Level(*level));
                 buffer.append(0, "]", Style::Level(*level));
                 label_width += 2 + code.len();
             }

compiler/rustc_errors/src/json.rs

@@ -17,6 +17,7 @@ use crate::translation::{to_fluent_args, Translate};
 use crate::DiagnosticId;
 use crate::{
     CodeSuggestion, FluentBundle, LazyFallbackBundle, MultiSpan, SpanLabel, SubDiagnostic,
+    TerminalUrl,
 };
 use rustc_lint_defs::Applicability;
 
@@ -47,6 +48,7 @@ pub struct JsonEmitter {
     diagnostic_width: Option<usize>,
     macro_backtrace: bool,
     track_diagnostics: bool,
+    terminal_url: TerminalUrl,
 }
 
 impl JsonEmitter {
@@ -60,6 +62,7 @@ impl JsonEmitter {
         diagnostic_width: Option<usize>,
         macro_backtrace: bool,
         track_diagnostics: bool,
+        terminal_url: TerminalUrl,
     ) -> JsonEmitter {
         JsonEmitter {
             dst: Box::new(io::BufWriter::new(io::stderr())),
@@ -73,6 +76,7 @@ impl JsonEmitter {
             diagnostic_width,
             macro_backtrace,
             track_diagnostics,
+            terminal_url,
         }
     }
 
@@ -84,6 +88,7 @@ impl JsonEmitter {
         diagnostic_width: Option<usize>,
         macro_backtrace: bool,
         track_diagnostics: bool,
+        terminal_url: TerminalUrl,
     ) -> JsonEmitter {
         let file_path_mapping = FilePathMapping::empty();
         JsonEmitter::stderr(
@@ -96,6 +101,7 @@ impl JsonEmitter {
             diagnostic_width,
             macro_backtrace,
             track_diagnostics,
+            terminal_url,
         )
     }
 
@@ -110,6 +116,7 @@ impl JsonEmitter {
         diagnostic_width: Option<usize>,
         macro_backtrace: bool,
         track_diagnostics: bool,
+        terminal_url: TerminalUrl,
     ) -> JsonEmitter {
         JsonEmitter {
             dst,
@@ -123,6 +130,7 @@ impl JsonEmitter {
             diagnostic_width,
             macro_backtrace,
             track_diagnostics,
+            terminal_url,
         }
     }
 
@@ -360,6 +368,7 @@ impl Diagnostic {
                 je.diagnostic_width,
                 je.macro_backtrace,
                 je.track_diagnostics,
+                je.terminal_url,
             )
             .ui_testing(je.ui_testing)
             .emit_diagnostic(diag);

compiler/rustc_errors/src/json/tests.rs

@@ -4,7 +4,7 @@ use crate::json::JsonEmitter;
 use rustc_span::source_map::{FilePathMapping, SourceMap};
 
 use crate::emitter::{ColorConfig, HumanReadableErrorType};
-use crate::Handler;
+use crate::{Handler, TerminalUrl};
 use rustc_span::{BytePos, Span};
 
 use std::str;
@@ -60,6 +60,7 @@ fn test_positions(code: &str, span: (u32, u32), expected_output: SpanTestData) {
             None,
             false,
             false,
+            TerminalUrl::No,
         );
 
         let span = Span::with_root_ctxt(BytePos(span.0), BytePos(span.1));

compiler/rustc_errors/src/lib.rs

@@ -573,6 +573,7 @@ impl Handler {
             None,
             flags.macro_backtrace,
             flags.track_diagnostics,
+            TerminalUrl::No,
         ));
         Self::with_emitter_and_flags(emitter, flags)
     }
@@ -1838,6 +1839,13 @@ pub fn add_elided_lifetime_in_path_suggestion(
     );
 }
 
+#[derive(Clone, Copy, PartialEq, Hash, Debug)]
+pub enum TerminalUrl {
+    No,
+    Yes,
+    Auto,
+}
+
 /// Useful type to use with `Result<>` indicate that an error has already
 /// been reported to the user, so no need to continue checking.
 #[derive(Clone, Copy, Debug, Encodable, Decodable, Hash, PartialEq, Eq, PartialOrd, Ord)]