make clean::Item::span return option instead of dummy span

src/librustdoc/clean/types.rs

@@ -415,29 +415,28 @@ impl Item {
             .unwrap_or(false)
     }
 
-    pub(crate) fn span(&self, tcx: TyCtxt<'_>) -> Span {
+    pub(crate) fn span(&self, tcx: TyCtxt<'_>) -> Option<Span> {
         let kind = match &*self.kind {
             ItemKind::StrippedItem(k) => k,
             _ => &*self.kind,
         };
         match kind {
-            ItemKind::ModuleItem(Module { span, .. }) => *span,
-            ItemKind::ImplItem(box Impl { kind: ImplKind::Auto, .. }) => Span::dummy(),
+            ItemKind::ModuleItem(Module { span, .. }) => Some(*span),
+            ItemKind::ImplItem(box Impl { kind: ImplKind::Auto, .. }) => None,
             ItemKind::ImplItem(box Impl { kind: ImplKind::Blanket(_), .. }) => {
                 if let ItemId::Blanket { impl_id, .. } = self.item_id {
-                    rustc_span(impl_id, tcx)
+                    Some(rustc_span(impl_id, tcx))
                 } else {
                     panic!("blanket impl item has non-blanket ID")
                 }
             }
-            _ => {
-                self.item_id.as_def_id().map(|did| rustc_span(did, tcx)).unwrap_or_else(Span::dummy)
-            }
+            _ => self.item_id.as_def_id().map(|did| rustc_span(did, tcx)),
         }
     }
 
     pub(crate) fn attr_span(&self, tcx: TyCtxt<'_>) -> rustc_span::Span {
-        crate::passes::span_of_attrs(&self.attrs).unwrap_or_else(|| self.span(tcx).inner())
+        crate::passes::span_of_attrs(&self.attrs)
+            .unwrap_or_else(|| self.span(tcx).map_or(rustc_span::DUMMY_SP, |span| span.inner()))
     }
 
     /// Finds the `doc` attribute as a NameValue and returns the corresponding
@@ -2109,14 +2108,6 @@ impl Span {
         self.0
     }
 
-    pub(crate) fn dummy() -> Self {
-        Self(rustc_span::DUMMY_SP)
-    }
-
-    pub(crate) fn is_dummy(&self) -> bool {
-        self.0.is_dummy()
-    }
-
     pub(crate) fn filename(&self, sess: &Session) -> FileName {
         sess.source_map().span_to_filename(self.0)
     }

src/librustdoc/html/render/context.rs

@@ -301,13 +301,12 @@ impl<'tcx> Context<'tcx> {
     /// may happen, for example, with externally inlined items where the source
     /// of their crate documentation isn't known.
     pub(super) fn src_href(&self, item: &clean::Item) -> Option<String> {
-        self.href_from_span(item.span(self.tcx()), true)
+        self.href_from_span(item.span(self.tcx())?, true)
     }
 
     pub(crate) fn href_from_span(&self, span: clean::Span, with_lines: bool) -> Option<String> {
-        if span.is_dummy() {
-            return None;
-        }
+        assert!(!span.inner().is_dummy());
+
         let mut root = self.root_path();
         let mut path = String::new();
         let cnum = span.cnum(self.sess());

src/librustdoc/html/render/mod.rs

@@ -2677,7 +2677,7 @@ fn render_call_locations(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Ite
         let contents = match fs::read_to_string(&path) {
             Ok(contents) => contents,
             Err(err) => {
-                let span = item.span(tcx).inner();
+                let span = item.span(tcx).map_or(rustc_span::DUMMY_SP, |span| span.inner());
                 tcx.sess
                     .span_err(span, &format!("failed to read file {}: {}", path.display(), err));
                 return false;

src/librustdoc/html/sources.rs

@@ -53,6 +53,7 @@ impl LocalSourcesCollector<'_, '_> {
     fn add_local_source(&mut self, item: &clean::Item) {
         let sess = self.tcx.sess;
         let span = item.span(self.tcx);
+        let Some(span) = span else { return };
         // skip all synthetic "files"
         if !is_real_and_local(span, sess) {
             return;
@@ -109,6 +110,7 @@ impl DocVisitor for SourceCollector<'_, '_> {
 
         let tcx = self.cx.tcx();
         let span = item.span(tcx);
+        let Some(span) = span else { return };
         let sess = tcx.sess;
 
         // If we're not rendering sources, there's nothing to do.

src/librustdoc/json/conversions.rs

@@ -59,7 +59,7 @@ impl JsonRenderer<'_> {
             id: from_item_id_with_name(item_id, self.tcx, name),
             crate_id: item_id.krate().as_u32(),
             name: name.map(|sym| sym.to_string()),
-            span: self.convert_span(span),
+            span: span.and_then(|span| self.convert_span(span)),
             visibility: self.convert_visibility(visibility),
             docs,
             attrs,

src/librustdoc/passes/calculate_doc_coverage.rs

@@ -215,7 +215,6 @@ impl<'a, 'b> DocVisitor for CoverageCalculator<'a, 'b> {
                     None,
                 );
 
-                let filename = i.span(self.ctx.tcx).filename(self.ctx.sess());
                 let has_doc_example = tests.found_tests != 0;
                 // The `expect_def_id()` should be okay because `local_def_id_to_hir_id`
                 // would presumably panic if a fake `DefIndex` were passed.
@@ -261,13 +260,16 @@ impl<'a, 'b> DocVisitor for CoverageCalculator<'a, 'b> {
                 let should_have_docs = !should_be_ignored
                     && (level != lint::Level::Allow || matches!(source, LintLevelSource::Default));
 
-                debug!("counting {:?} {:?} in {:?}", i.type_(), i.name, filename);
-                self.items.entry(filename).or_default().count_item(
-                    has_docs,
-                    has_doc_example,
-                    should_have_doc_example(self.ctx, i),
-                    should_have_docs,
-                );
+                if let Some(span) = i.span(self.ctx.tcx) {
+                    let filename = span.filename(self.ctx.sess());
+                    debug!("counting {:?} {:?} in {:?}", i.type_(), i.name, filename);
+                    self.items.entry(filename).or_default().count_item(
+                        has_docs,
+                        has_doc_example,
+                        should_have_doc_example(self.ctx, i),
+                        should_have_docs,
+                    );
+                }
             }
         }
 

src/test/rustdoc-json/impls/auto.rs

@@ -0,0 +1,10 @@
+#![feature(no_core, auto_traits, lang_items)]
+#![no_core]
+
+#[lang = "sized"]
+trait Sized {}
+
+pub auto trait Bar {}
+
+// @has auto.json "$.index[*][?(@.kind=='impl')].span" null
+pub struct Foo;