Add Rustdoc book link to scrape examples help. Remove remaining panic

locations in scrape examples.

src/librustdoc/html/render/mod.rs

@@ -79,6 +79,7 @@
 use crate::html::static_files::SCRAPE_EXAMPLES_HELP_MD;
 use crate::scrape_examples::{CallData, CallLocation};
 use crate::try_none;
+use crate::DOC_RUST_LANG_ORG_CHANNEL;
 
 /// A pair of name and its optional document.
 crate type NameDoc = (String, Option<String>);
@@ -463,17 +464,22 @@ fn settings(root_path: &str, suffix: &str, theme_names: Vec<String>) -> Result<S
 }
 
 fn scrape_examples_help(shared: &SharedContext<'_>) -> String {
-    let content = SCRAPE_EXAMPLES_HELP_MD;
+    let mut content = SCRAPE_EXAMPLES_HELP_MD.to_owned();
+    content.push_str(&format!(
+      "## More information\n\n\
+      If you want more information about this feature, please read the [corresponding chapter in the Rustdoc book]({}/rustdoc/scraped-examples.html).",
+      DOC_RUST_LANG_ORG_CHANNEL));
+
     let mut ids = IdMap::default();
     format!(
-        "<div class=\"main-heading\">
+        "<div class=\"main-heading\">\
             <h1 class=\"fqn\">\
                 <span class=\"in-band\">About scraped examples</span>\
             </h1>\
         </div>\
         <div>{}</div>",
         Markdown {
-            content,
+            content: &content,
             links: &[],
             ids: &mut ids,
             error_codes: shared.codes,

src/librustdoc/scrape_examples.rs

@@ -71,14 +71,14 @@ impl ScrapeExamplesOptions {
 }
 
 impl SyntaxRange {
-    fn new(span: rustc_span::Span, file: &SourceFile) -> Self {
+    fn new(span: rustc_span::Span, file: &SourceFile) -> Option<Self> {
         let get_pos = |bytepos: BytePos| file.original_relative_byte_pos(bytepos).0;
-        let get_line = |bytepos: BytePos| file.lookup_line(bytepos).unwrap();
+        let get_line = |bytepos: BytePos| file.lookup_line(bytepos);
 
-        SyntaxRange {
+        Some(SyntaxRange {
             byte_span: (get_pos(span.lo()), get_pos(span.hi())),
-            line_span: (get_line(span.lo()), get_line(span.hi())),
-        }
+            line_span: (get_line(span.lo())?, get_line(span.hi())?),
+        })
     }
 }
 
@@ -95,12 +95,12 @@ fn new(
         ident_span: rustc_span::Span,
         enclosing_item_span: rustc_span::Span,
         source_file: &SourceFile,
-    ) -> Self {
-        CallLocation {
-            call_expr: SyntaxRange::new(expr_span, source_file),
-            call_ident: SyntaxRange::new(ident_span, source_file),
-            enclosing_item: SyntaxRange::new(enclosing_item_span, source_file),
-        }
+    ) -> Option<Self> {
+        Some(CallLocation {
+            call_expr: SyntaxRange::new(expr_span, source_file)?,
+            call_ident: SyntaxRange::new(ident_span, source_file)?,
+            enclosing_item: SyntaxRange::new(enclosing_item_span, source_file)?,
+        })
     }
 }
 
@@ -178,7 +178,7 @@ fn visit_expr(&mut self, ex: &'tcx hir::Expr<'tcx>) {
         // If this span comes from a macro expansion, then the source code may not actually show
         // a use of the given item, so it would be a poor example. Hence, we skip all uses in macros.
         if call_span.from_expansion() {
-            trace!("Rejecting expr from macro: {:?}", call_span);
+            trace!("Rejecting expr from macro: {call_span:?}");
             return;
         }
 
@@ -188,7 +188,7 @@ fn visit_expr(&mut self, ex: &'tcx hir::Expr<'tcx>) {
             .hir()
             .span_with_body(tcx.hir().local_def_id_to_hir_id(tcx.hir().get_parent_item(ex.hir_id)));
         if enclosing_item_span.from_expansion() {
-            trace!("Rejecting expr ({:?}) from macro item: {:?}", call_span, enclosing_item_span);
+            trace!("Rejecting expr ({call_span:?}) from macro item: {enclosing_item_span:?}");
             return;
         }
 
@@ -224,11 +224,27 @@ fn visit_expr(&mut self, ex: &'tcx hir::Expr<'tcx>) {
             };
 
             if let Some(file_path) = file_path {
-                let abs_path = fs::canonicalize(file_path.clone()).unwrap();
+                let abs_path = match fs::canonicalize(file_path.clone()) {
+                    Ok(abs_path) => abs_path,
+                    Err(_) => {
+                        trace!("Could not canonicalize file path: {}", file_path.display());
+                        return;
+                    }
+                };
+
                 let cx = &self.cx;
+                let clean_span = crate::clean::types::Span::new(call_span);
+                let url = match cx.href_from_span(clean_span, false) {
+                    Some(url) => url,
+                    None => {
+                        trace!(
+                            "Rejecting expr ({call_span:?}) whose clean span ({clean_span:?}) cannot be turned into a link"
+                        );
+                        return;
+                    }
+                };
+
                 let mk_call_data = || {
-                    let clean_span = crate::clean::types::Span::new(call_span);
-                    let url = cx.href_from_span(clean_span, false).unwrap();
                     let display_name = file_path.display().to_string();
                     let edition = call_span.edition();
                     CallData { locations: Vec::new(), url, display_name, edition }
@@ -240,7 +256,14 @@ fn visit_expr(&mut self, ex: &'tcx hir::Expr<'tcx>) {
                 trace!("Including expr: {:?}", call_span);
                 let enclosing_item_span =
                     source_map.span_extend_to_prev_char(enclosing_item_span, '\n', false);
-                let location = CallLocation::new(call_span, ident_span, enclosing_item_span, &file);
+                let location =
+                    match CallLocation::new(call_span, ident_span, enclosing_item_span, &file) {
+                        Some(location) => location,
+                        None => {
+                            trace!("Could not get serializable call location for {call_span:?}");
+                            return;
+                        }
+                    };
                 fn_entries.entry(abs_path).or_insert_with(mk_call_data).locations.push(location);
             }
         }
@@ -274,8 +297,8 @@ fn visit_expr(&mut self, ex: &'tcx hir::Expr<'tcx>) {
             .map(|(crate_num, _)| **crate_num)
             .collect::<Vec<_>>();
 
-        debug!("All crates in TyCtxt: {:?}", all_crates);
-        debug!("Scrape examples target_crates: {:?}", target_crates);
+        debug!("All crates in TyCtxt: {all_crates:?}");
+        debug!("Scrape examples target_crates: {target_crates:?}");
 
         // Run call-finder on all items
         let mut calls = FxHashMap::default();