rustc_errors: Use ensure_source_file_source_present where necessary.

src/librustc_errors/emitter.rs

@@ -422,9 +422,11 @@ pub trait Emitter {
         span: &mut MultiSpan,
         children: &mut Vec<SubDiagnostic>,
     ) {
-        for span in iter::once(span).chain(children.iter_mut().map(|child| &mut child.span)) {
+        debug!("fix_multispans_in_extern_macros: before: span={:?} children={:?}", span, children);
+        for span in iter::once(&mut *span).chain(children.iter_mut().map(|child| &mut child.span)) {
             self.fix_multispan_in_extern_macros(source_map, span);
         }
+        debug!("fix_multispans_in_extern_macros: after: span={:?} children={:?}", span, children);
     }
 
     // This "fixes" MultiSpans that contain `Span`s pointing to locations inside of external macros.
@@ -472,6 +474,7 @@ impl Emitter for EmitterWriter {
     fn emit_diagnostic(&mut self, diag: &Diagnostic) {
         let mut children = diag.children.clone();
         let (mut primary_span, suggestions) = self.primary_span_formatted(&diag);
+        debug!("emit_diagnostic: suggestions={:?}", suggestions);
 
         self.fix_multispans_in_extern_macros_and_render_macro_backtrace(
             &self.sm,
@@ -1533,6 +1536,7 @@ impl EmitterWriter {
 
         // Render the replacements for each suggestion
         let suggestions = suggestion.splice_lines(&**sm);
+        debug!("emit_suggestion_default: suggestions={:?}", suggestions);
 
         if suggestions.is_empty() {
             // Suggestions coming from macros can have malformed spans. This is a heavy handed

src/librustc_errors/json.rs

@@ -394,6 +394,11 @@ impl DiagnosticSpanLine {
         je.sm
             .span_to_lines(span)
             .map(|lines| {
+                // We can't get any lines if the source is unavailable.
+                if !je.sm.ensure_source_file_source_present(lines.file.clone()) {
+                    return vec![];
+                }
+
                 let sf = &*lines.file;
                 lines
                     .lines

src/librustc_errors/lib.rs

@@ -196,6 +196,11 @@ impl CodeSuggestion {
                 let lines = sm.span_to_lines(bounding_span).ok()?;
                 assert!(!lines.lines.is_empty());
 
+                // We can't splice anything if the source is unavailable.
+                if !sm.ensure_source_file_source_present(lines.file.clone()) {
+                    return None;
+                }
+
                 // To build up the result, we do this for each span:
                 // - push the line segment trailing the previous span
                 //   (at the beginning a "phantom" span pointing at the start of the line)

src/test/ui/consts/miri_unleashed/mutable_const2.stderr

@@ -10,7 +10,7 @@ error: internal compiler error: mutable allocation in constant
 LL | const MUTABLE_BEHIND_RAW: *mut i32 = &UnsafeCell::new(42) as *const _ as *mut _;
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-thread 'rustc' panicked at 'no errors encountered even though `delay_span_bug` issued', src/librustc_errors/lib.rs:355:17
+thread 'rustc' panicked at 'no errors encountered even though `delay_span_bug` issued', src/librustc_errors/lib.rs:360:17
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
 
 error: internal compiler error: unexpected panic

src/test/ui/editions/edition-keywords-2015-2018-expansion.stderr

@@ -7,8 +7,8 @@ LL |     produces_async! {}
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 help: you can escape reserved keywords to use them as identifiers
    |
-LL | r#async
-   |
+LL |     () => (pub fn r#async() {})
+   |                   ^^^^^^^
 
 error: aborting due to previous error
 

src/test/ui/editions/edition-keywords-2018-2018-expansion.stderr

@@ -7,8 +7,8 @@ LL |     produces_async! {}
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 help: you can escape reserved keywords to use them as identifiers
    |
-LL | r#async
-   |
+LL |     () => (pub fn r#async() {})
+   |                   ^^^^^^^
 
 error: aborting due to previous error