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, 5 insertions, 9 deletions

diff --git a/src/librustdoc/doctest/make.rs b/src/librustdoc/doctest/make.rs
index 4edd5433de6..d5c965f7053 100644
--- a/src/librustdoc/doctest/make.rs
+++ b/src/librustdoc/doctest/make.rs
@@ -345,7 +345,7 @@ fn parse_source(source: &str, crate_name: &Option<&str>) -> Result<ParseSourceIn
     fn check_item(item: &ast::Item, info: &mut ParseSourceInfo, crate_name: &Option<&str>) -> bool {
         let mut is_extern_crate = false;
         if !info.has_global_allocator
-            && item.attrs.iter().any(|attr| attr.name_or_empty() == sym::global_allocator)
+            && item.attrs.iter().any(|attr| attr.has_name(sym::global_allocator))
         {
             info.has_global_allocator = true;
         }
@@ -377,7 +377,7 @@ fn parse_source(source: &str, crate_name: &Option<&str>) -> Result<ParseSourceIn
     }
 
     let mut prev_span_hi = 0;
-    let not_crate_attrs = [sym::forbid, sym::allow, sym::warn, sym::deny, sym::expect];
+    let not_crate_attrs = &[sym::forbid, sym::allow, sym::warn, sym::deny, sym::expect];
     let parsed = parser.parse_item(rustc_parse::parser::ForceCollect::No);
 
     let result = match parsed {
@@ -386,17 +386,13 @@ fn parse_source(source: &str, crate_name: &Option<&str>) -> Result<ParseSourceIn
                 && let Some(ref body) = fn_item.body =>
         {
             for attr in &item.attrs {
-                let attr_name = attr.name_or_empty();
-
-                if attr.style == AttrStyle::Outer || not_crate_attrs.contains(&attr_name) {
+                if attr.style == AttrStyle::Outer || attr.has_any_name(not_crate_attrs) {
                     // There is one exception to these attributes:
                     // `#![allow(internal_features)]`. If this attribute is used, we need to
                     // consider it only as a crate-level attribute.
-                    if attr_name == sym::allow
+                    if attr.has_name(sym::allow)
                         && let Some(list) = attr.meta_item_list()
-                        && list.iter().any(|sub_attr| {
-                            sub_attr.name_or_empty().as_str() == "internal_features"
-                        })
+                        && list.iter().any(|sub_attr| sub_attr.has_name(sym::internal_features))
                     {
                         push_to_s(&mut info.crate_attrs, source, attr.span, &mut prev_span_hi);
                     } else {