Suggest only Span without source changes when source code is unavailable

compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs

@@ -47,6 +47,7 @@ pub struct AnnotateSnippetEmitter {
     track_diagnostics: bool,
     terminal_url: TerminalUrl,
     theme: OutputTheme,
+    show_suggestions_with_unavailable_source: bool,
 }
 
 impl Debug for AnnotateSnippetEmitter {
@@ -63,6 +64,10 @@ impl Debug for AnnotateSnippetEmitter {
             .field("track_diagnostics", &self.track_diagnostics)
             .field("terminal_url", &self.terminal_url)
             .field("theme", &self.theme)
+            .field(
+                "show_suggestions_with_unavailable_source",
+                &self.show_suggestions_with_unavailable_source,
+            )
             .finish()
     }
 }
@@ -136,6 +141,7 @@ impl AnnotateSnippetEmitter {
             track_diagnostics: false,
             terminal_url: TerminalUrl::No,
             theme: OutputTheme::Ascii,
+            show_suggestions_with_unavailable_source: false,
         }
     }
 
@@ -307,6 +313,12 @@ impl AnnotateSnippetEmitter {
                 SuggestionStyle::HideCodeInline
                 | SuggestionStyle::ShowCode
                 | SuggestionStyle::ShowAlways => {
+                    // Get the original unavailable spans before `suggestion` is consumed.
+                    let unavailable_source_span = if self.show_suggestions_with_unavailable_source {
+                        self.suggestion_span_with_unavailable_source(sm, &suggestion)
+                    } else {
+                        None
+                    };
                     let substitutions = suggestion
                         .substitutions
                         .into_iter()
@@ -356,6 +368,30 @@ impl AnnotateSnippetEmitter {
                         .collect::<Vec<_>>();
 
                     if substitutions.is_empty() {
+                        if let Some(span) = unavailable_source_span {
+                            let msg = format_diag_message(&suggestion.msg, args).to_string();
+                            report.push(std::mem::replace(
+                                &mut group,
+                                Group::with_title(
+                                    annotate_snippets::Level::HELP.secondary_title(msg),
+                                ),
+                            ));
+
+                            let file_ann = collect_annotations(args, &span, sm);
+                            let level = annotate_snippets::Level::HELP;
+                            for (file_idx, (file, annotations)) in file_ann.into_iter().enumerate()
+                            {
+                                group = self.unannotated_messages(
+                                    annotations,
+                                    &file.name,
+                                    sm,
+                                    file_idx,
+                                    &mut report,
+                                    group,
+                                    &level,
+                                );
+                            }
+                        }
                         continue;
                     }
                     let mut msg = format_diag_message(&suggestion.msg, args).to_string();
@@ -645,6 +681,34 @@ impl AnnotateSnippetEmitter {
         }
         group
     }
+
+    fn suggestion_span_with_unavailable_source(
+        &self,
+        sm: &Arc<SourceMap>,
+        suggestion: &CodeSuggestion,
+    ) -> Option<MultiSpan> {
+        // These spans cannot be rendered as source patches because their source
+        // files are unavailable, but can still be shown as locations.
+        let spans = suggestion
+            .substitutions
+            .iter()
+            .flat_map(|subst| &subst.parts)
+            .filter_map(|part| {
+                if sm.is_valid_span(part.span).is_err() {
+                    debug!("suggestion contains an invalid span: {:?}", part);
+                    return None;
+                }
+                let lines = sm.span_to_lines(part.span).ok()?;
+                if sm.ensure_source_file_source_present(&lines.file) {
+                    None
+                } else {
+                    Some(part.span)
+                }
+            })
+            .collect::<Vec<_>>();
+
+        if spans.is_empty() { None } else { Some(MultiSpan::from_spans(spans)) }
+    }
 }
 
 fn emit_to_destination(

compiler/rustc_errors/src/json.rs

@@ -54,6 +54,7 @@ pub struct JsonEmitter {
     macro_backtrace: bool,
     track_diagnostics: bool,
     terminal_url: TerminalUrl,
+    show_suggestions_with_unavailable_source: bool,
 }
 
 impl JsonEmitter {
@@ -76,6 +77,7 @@ impl JsonEmitter {
             macro_backtrace: false,
             track_diagnostics: false,
             terminal_url: TerminalUrl::No,
+            show_suggestions_with_unavailable_source: false,
         }
     }
 
@@ -373,6 +375,7 @@ impl Diagnostic {
             .terminal_url(je.terminal_url)
             .ui_testing(je.ui_testing)
             .ignored_directories_in_source_blocks(je.ignored_directories_in_source_blocks.clone())
+            .show_suggestions_with_unavailable_source(je.show_suggestions_with_unavailable_source)
             .theme(if je.json_rendered.unicode { OutputTheme::Unicode } else { OutputTheme::Ascii })
             .emit_diagnostic(diag);
 

compiler/rustc_session/src/options.rs

@@ -2629,6 +2629,8 @@ written to standard error output)"),
         "make the current crate share its generic instantiations"),
     shell_argfiles: bool = (false, parse_bool, [UNTRACKED],
         "allow argument files to be specified with POSIX \"shell-style\" argument quoting"),
+    show_suggestions_with_unavailable_source: bool = (false, parse_bool, [UNTRACKED],
+        "show span-only suggestions when the source code is unavailable"),
     simulate_remapped_rust_src_base: Option<PathBuf> = (None, parse_opt_pathbuf, [TRACKED],
         "simulate the effect of remap-debuginfo = true at bootstrapping by remapping path \
         to rust's source base directory. only meant for testing purposes"),

compiler/rustc_session/src/session.rs

@@ -947,6 +947,8 @@ impl Session {
 fn default_emitter(sopts: &config::Options, source_map: Arc<SourceMap>) -> Box<DynEmitter> {
     let macro_backtrace = sopts.unstable_opts.macro_backtrace;
     let track_diagnostics = sopts.unstable_opts.track_diagnostics;
+    let show_suggestions_with_unavailable_source =
+        sopts.unstable_opts.show_suggestions_with_unavailable_source;
     let terminal_url = match sopts.unstable_opts.terminal_urls {
         TerminalUrl::Auto => {
             match (std::env::var("COLORTERM").as_deref(), std::env::var("TERM").as_deref()) {
@@ -974,6 +976,9 @@ fn default_emitter(sopts: &config::Options, source_map: Arc<SourceMap>) -> Box<D
                     .track_diagnostics(track_diagnostics)
                     .terminal_url(terminal_url)
                     .theme(if unicode { OutputTheme::Unicode } else { OutputTheme::Ascii })
+                    .show_suggestions_with_unavailable_source(
+                        show_suggestions_with_unavailable_source,
+                    )
                     .ignored_directories_in_source_blocks(
                         sopts.unstable_opts.ignore_directory_in_diagnostics_source_blocks.clone(),
                     );
@@ -995,7 +1000,8 @@ fn default_emitter(sopts: &config::Options, source_map: Arc<SourceMap>) -> Box<D
             .diagnostic_width(sopts.diagnostic_width)
             .macro_backtrace(macro_backtrace)
             .track_diagnostics(track_diagnostics)
-            .terminal_url(terminal_url),
+            .terminal_url(terminal_url)
+            .show_suggestions_with_unavailable_source(show_suggestions_with_unavailable_source),
         ),
     }
 }

src/tools/compiletest/src/runtest.rs

@@ -1704,6 +1704,7 @@ impl<'test> TestCx<'test> {
                 compiler.arg("-Ccodegen-units=1");
                 // Hide line numbers to reduce churn
                 compiler.arg("-Zui-testing");
+                compiler.arg("-Zshow-suggestions-with-unavailable-source");
                 compiler.arg("-Zdeduplicate-diagnostics=no");
                 compiler.arg("-Zwrite-long-types-to-disk=no");
                 // FIXME: use this for other modes too, for perf?

tests/ui/consts/const_in_pattern/suggest_equality_comparison_instead_of_pattern_matching.stderr

@@ -147,6 +147,8 @@ LL |         if let V = vec![] {}
    = note: `Vec<()>` is not usable in patterns
    |
    = note: see https://doc.rust-lang.org/stable/std/marker/trait.StructuralPartialEq.html for details
+help: check for equality instead of pattern matching
+  --> $SRC_DIR/alloc/src/macros.rs:LL:COL
 
 error: constant of non-structural type `Vec<()>` in a pattern
   --> $DIR/suggest_equality_comparison_instead_of_pattern_matching.rs:28:13

tests/ui/pin-ergonomics/pinned-drop-check.stderr

@@ -283,36 +283,54 @@ error[E0040]: explicit use of destructor method
    |
 LL |             Drop::pin_drop(todo!());
    |             ^^^^^^^^^^^^^^ explicit destructor calls not allowed
+   |
+help: consider using `drop` function
+  --> $SRC_DIR/core/src/macros/mod.rs:LL:COL
 
 error[E0040]: explicit use of destructor method
   --> $DIR/pinned-drop-check.rs:156:13
    |
 LL |             Drop::pin_drop(todo!());
    |             ^^^^^^^^^^^^^^ explicit destructor calls not allowed
+   |
+help: consider using `drop` function
+  --> $SRC_DIR/core/src/macros/mod.rs:LL:COL
 
 error[E0040]: explicit use of destructor method
   --> $DIR/pinned-drop-check.rs:168:13
    |
 LL |             Drop::drop(todo!());
    |             ^^^^^^^^^^ explicit destructor calls not allowed
+   |
+help: consider using `drop` function
+  --> $SRC_DIR/core/src/macros/mod.rs:LL:COL
 
 error[E0040]: explicit use of destructor method
   --> $DIR/pinned-drop-check.rs:173:13
    |
 LL |             Drop::drop(todo!());
    |             ^^^^^^^^^^ explicit destructor calls not allowed
+   |
+help: consider using `drop` function
+  --> $SRC_DIR/core/src/macros/mod.rs:LL:COL
 
 error[E0040]: explicit use of destructor method
   --> $DIR/pinned-drop-check.rs:183:13
    |
 LL |             Drop::drop(todo!());
    |             ^^^^^^^^^^ explicit destructor calls not allowed
+   |
+help: consider using `drop` function
+  --> $SRC_DIR/core/src/macros/mod.rs:LL:COL
 
 error[E0040]: explicit use of destructor method
   --> $DIR/pinned-drop-check.rs:184:13
    |
 LL |             Drop::pin_drop(todo!());
    |             ^^^^^^^^^^^^^^ explicit destructor calls not allowed
+   |
+help: consider using `drop` function
+  --> $SRC_DIR/core/src/macros/mod.rs:LL:COL
 
 error: aborting due to 25 previous errors
 

tests/ui/structs/ice-line-bounds-issue-148684.stderr

@@ -9,6 +9,9 @@ LL | | }
 ...
 LL |       A(2, vec![])
    |       ^^^^^^^^^^^^
+   |
+help: use struct literal syntax instead of calling
+  --> $SRC_DIR/alloc/src/macros.rs:LL:COL
 
 error: aborting due to 1 previous error