Replace infallible `name_or_empty` methods with fallible `name` methods.

I'm removing empty identifiers everywhere, because in practice they
always mean "no identifier" rather than "empty identifier". (An empty
identifier is impossible.) It's better to use `Option` to mean "no
identifier" because you then can't forget about the "no identifier"
possibility.

Some specifics:
- When testing an attribute for a single name, the commit uses the
  `has_name` method.
- When testing an attribute for multiple names, the commit uses the new
  `has_any_name` method.
- When using `match` on an attribute, the match arms now have `Some` on
  them.

In the tests, we now avoid printing empty identifiers by not printing
the identifier in the `error:` line at all, instead letting the carets
point out the problem.

1 files changed, 6 insertions, 6 deletions

diff --git a/src/librustdoc/html/render/context.rs b/src/librustdoc/html/render/context.rs
index 596ac665fc3..f22935df96c 100644
--- a/src/librustdoc/html/render/context.rs
+++ b/src/librustdoc/html/render/context.rs
@@ -521,23 +521,23 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
         // Crawl the crate attributes looking for attributes which control how we're
         // going to emit HTML
         for attr in krate.module.attrs.lists(sym::doc) {
-            match (attr.name_or_empty(), attr.value_str()) {
-                (sym::html_favicon_url, Some(s)) => {
+            match (attr.name(), attr.value_str()) {
+                (Some(sym::html_favicon_url), Some(s)) => {
                     layout.favicon = s.to_string();
                 }
-                (sym::html_logo_url, Some(s)) => {
+                (Some(sym::html_logo_url), Some(s)) => {
                     layout.logo = s.to_string();
                 }
-                (sym::html_playground_url, Some(s)) => {
+                (Some(sym::html_playground_url), Some(s)) => {
                     playground = Some(markdown::Playground {
                         crate_name: Some(krate.name(tcx)),
                         url: s.to_string(),
                     });
                 }
-                (sym::issue_tracker_base_url, Some(s)) => {
+                (Some(sym::issue_tracker_base_url), Some(s)) => {
                     issue_tracker_base_url = Some(s.to_string());
                 }
-                (sym::html_no_source, None) if attr.is_word() => {
+                (Some(sym::html_no_source), None) if attr.is_word() => {
                     include_sources = false;
                 }
                 _ => {}