Suggest Span without source changes when source code is unavailable

xizheyin · xizheyin · commit e17fa3686cac · 2026-05-24T22:02:56.000+08:00
diff --git a/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs b/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 +313,11 @@ impl AnnotateSnippetEmitter {
                 SuggestionStyle::HideCodeInline
                 | SuggestionStyle::ShowCode
                 | SuggestionStyle::ShowAlways => {
+                    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()
@@ -341,8 +352,19 @@ impl AnnotateSnippetEmitter {
                                 return None;
                             }
 
-                            // We can't splice anything if the source is unavailable.
-                            if !sm.ensure_source_file_source_present(&lo_file) {
+                            // We can't splice anything if the source is unavailable. When the
+                            // span-only fallback is enabled, also avoid rendering source that was
+                            // intentionally hidden from diagnostics.
+                            let can_show_source = if self.show_suggestions_with_unavailable_source {
+                                should_show_source_code(
+                                    &self.ignored_directories_in_source_blocks,
+                                    sm,
+                                    &lo_file,
+                                )
+                            } else {
+                                sm.ensure_source_file_source_present(&lo_file)
+                            };
+                            if !can_show_source {
                                 return None;
                             }
 
@@ -356,6 +378,30 @@ 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 +691,36 @@ impl AnnotateSnippetEmitter {
         }
         group
     }
+
+    fn suggestion_span_with_unavailable_source(
+        &self,
+        sm: &Arc<SourceMap>,
+        suggestion: &CodeSuggestion,
+    ) -> Option<MultiSpan> {
+        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 should_show_source_code(
+                    &self.ignored_directories_in_source_blocks,
+                    sm,
+                    &lines.file,
+                ) {
+                    None
+                } else {
+                    Some(part.span)
+                }
+            })
+            .collect::<Vec<_>>();
+
+        if spans.is_empty() { None } else { Some(MultiSpan::from_spans(spans)) }
+    }
 }
 
 fn emit_to_destination(
diff --git a/compiler/rustc_errors/src/json.rs b/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);
 
diff --git a/compiler/rustc_session/src/options.rs b/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"),
diff --git a/compiler/rustc_session/src/session.rs b/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),
         ),
     }
 }
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
@@ -1694,6 +1694,7 @@ impl<'test> TestCx<'test> {
                     compiler.args(&["--json", "future-incompat"]);
                 }
                 compiler.arg("-Zui-testing");
+                compiler.arg("-Zshow-suggestions-with-unavailable-source");
                 compiler.arg("-Zdeduplicate-diagnostics=no");
             }
             TestMode::Ui => {
@@ -1704,6 +1705,7 @@ 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?
diff --git a/tests/ui/compiletest-self-test/help-show-std-source.rs b/tests/ui/compiletest-self-test/help-show-std-source.rs
@@ -0,0 +1,12 @@
+//@ compile-flags: -Zignore-directory-in-diagnostics-source-blocks={{src-base}}/compiletest-self-test
+
+macro_rules! my_assert {
+    ($left:expr, $right:expr) => {
+        if !($left == $right) {} //~ ERROR can't compare `&isize` with `{integer}` [E0277]
+    };
+}
+
+fn main() {
+    let y: &isize = &1;
+    my_assert!(y, 2);
+}
diff --git a/tests/ui/compiletest-self-test/help-show-std-source.stderr b/tests/ui/compiletest-self-test/help-show-std-source.stderr
@@ -0,0 +1,16 @@
+error[E0277]: can't compare `&isize` with `{integer}`
+  --> $DIR/help-show-std-source.rs:5:19
+   |
+   = note: no implementation for `&isize == {integer}`
+  ::: $DIR/help-show-std-source.rs:11:4
+   |
+   = note: in this macro invocation
+   |
+   = help: the trait `PartialEq<{integer}>` is not implemented for `&isize`
+   = note: this error originates in the macro `my_assert` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider dereferencing here
+  --> $DIR/help-show-std-source.rs:11:15
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0277`.

Original file line number	Diff line number	Diff line change
`@@ -54,6 +54,7 @@ pub struct JsonEmitter {`
`54`	`54`	`macro_backtrace: bool,`
`55`	`55`	`track_diagnostics: bool,`
`56`	`56`	`terminal_url: TerminalUrl,`
	`57`	`+ show_suggestions_with_unavailable_source: bool,`
`57`	`58`	`}`
`58`	`59`
`59`	`60`	`impl JsonEmitter {`
`@@ -76,6 +77,7 @@ impl JsonEmitter {`
`76`	`77`	`macro_backtrace: false,`
`77`	`78`	`track_diagnostics: false,`
`78`	`79`	`terminal_url: TerminalUrl::No,`
	`80`	`+ show_suggestions_with_unavailable_source: false,`
`79`	`81`	`}`
`80`	`82`	`}`
`81`	`83`
`@@ -373,6 +375,7 @@ impl Diagnostic {`
`373`	`375`	`.terminal_url(je.terminal_url)`
`374`	`376`	`.ui_testing(je.ui_testing)`
`375`	`377`	`.ignored_directories_in_source_blocks(je.ignored_directories_in_source_blocks.clone())`
	`378`	`+ .show_suggestions_with_unavailable_source(je.show_suggestions_with_unavailable_source)`
`376`	`379`	`.theme(if je.json_rendered.unicode { OutputTheme::Unicode } else { OutputTheme::Ascii })`
`377`	`380`	`.emit_diagnostic(diag);`
`378`	`381`