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.

2 files changed, 9 insertions, 9 deletions

diff --git a/compiler/rustc_attr_parsing/src/attributes/cfg.rs b/compiler/rustc_attr_parsing/src/attributes/cfg.rs
index 0d6d521b40c..a40112e27a2 100644
--- a/compiler/rustc_attr_parsing/src/attributes/cfg.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/cfg.rs
@@ -117,7 +117,7 @@ pub fn eval_condition(
     };
 
     match &cfg.kind {
-        MetaItemKind::List(mis) if cfg.name_or_empty() == sym::version => {
+        MetaItemKind::List(mis) if cfg.has_name(sym::version) => {
             try_gate_cfg(sym::version, cfg.span, sess, features);
             let (min_version, span) = match &mis[..] {
                 [MetaItemInner::Lit(MetaItemLit { kind: LitKind::Str(sym, ..), span, .. })] => {
@@ -164,18 +164,18 @@ pub fn eval_condition(
 
             // The unwraps below may look dangerous, but we've already asserted
             // that they won't fail with the loop above.
-            match cfg.name_or_empty() {
-                sym::any => mis
+            match cfg.name() {
+                Some(sym::any) => mis
                     .iter()
                     // We don't use any() here, because we want to evaluate all cfg condition
                     // as eval_condition can (and does) extra checks
                     .fold(false, |res, mi| res | eval_condition(mi, sess, features, eval)),
-                sym::all => mis
+                Some(sym::all) => mis
                     .iter()
                     // We don't use all() here, because we want to evaluate all cfg condition
                     // as eval_condition can (and does) extra checks
                     .fold(true, |res, mi| res & eval_condition(mi, sess, features, eval)),
-                sym::not => {
+                Some(sym::not) => {
                     let [mi] = mis.as_slice() else {
                         dcx.emit_err(session_diagnostics::ExpectedOneCfgPattern { span: cfg.span });
                         return false;
@@ -183,7 +183,7 @@ pub fn eval_condition(
 
                     !eval_condition(mi, sess, features, eval)
                 }
-                sym::target => {
+                Some(sym::target) => {
                     if let Some(features) = features
                         && !features.cfg_target_compact()
                     {
diff --git a/compiler/rustc_attr_parsing/src/context.rs b/compiler/rustc_attr_parsing/src/context.rs
index 3bf03f84ce8..972614a3366 100644
--- a/compiler/rustc_attr_parsing/src/context.rs
+++ b/compiler/rustc_attr_parsing/src/context.rs
@@ -222,7 +222,7 @@ impl<'sess> AttributeParser<'sess> {
             // if we're only looking for a single attribute,
             // skip all the ones we don't care about
             if let Some(expected) = self.parse_only {
-                if attr.name_or_empty() != expected {
+                if !attr.has_name(expected) {
                     continue;
                 }
             }
@@ -232,7 +232,7 @@ impl<'sess> AttributeParser<'sess> {
             // that's expanded right? But no, sometimes, when parsing attributes on macros,
             // we already use the lowering logic and these are still there. So, when `omit_doc`
             // is set we *also* want to ignore these
-            if omit_doc == OmitDoc::Skip && attr.name_or_empty() == sym::doc {
+            if omit_doc == OmitDoc::Skip && attr.has_name(sym::doc) {
                 continue;
             }
 
@@ -250,7 +250,7 @@ impl<'sess> AttributeParser<'sess> {
                     }))
                 }
                 // // FIXME: make doc attributes go through a proper attribute parser
-                // ast::AttrKind::Normal(n) if n.name_or_empty() == sym::doc => {
+                // ast::AttrKind::Normal(n) if n.has_name(sym::doc) => {
                 //     let p = GenericMetaItemParser::from_attr(&n, self.dcx());
                 //
                 //     attributes.push(Attribute::Parsed(AttributeKind::DocComment {