Auto merge of #58899 - petrochenkov:derval2, r=estebank

Do not accidentally treat multi-segment meta-items as single-segment

Fixes #55168 and many other regressions from #50030

Basically, attributes like `#[any::prefix::foo]` were commonly interpreted as `#[foo]` due to `name()` successfully returning the last segment (this applies to nested things as well `#[attr(any::prefix::foo)]`).

src/librustc/hir/check_attr.rs

@@ -166,7 +166,7 @@ impl<'a, 'tcx> CheckAttrVisitor<'a, 'tcx> {
         // ```
         let hints: Vec<_> = item.attrs
             .iter()
-            .filter(|attr| attr.name() == "repr")
+            .filter(|attr| attr.check_name("repr"))
             .filter_map(|attr| attr.meta_item_list())
             .flatten()
             .collect();
@@ -177,15 +177,15 @@ impl<'a, 'tcx> CheckAttrVisitor<'a, 'tcx> {
         let mut is_transparent = false;
 
         for hint in &hints {
-            let name = if let Some(name) = hint.name() {
+            let name = if let Some(name) = hint.ident_str() {
                 name
             } else {
                 // Invalid repr hint like repr(42). We don't check for unrecognized hints here
                 // (libsyntax does that), so just ignore it.
                 continue;
             };
 
-            let (article, allowed_targets) = match &*name.as_str() {
+            let (article, allowed_targets) = match name {
                 "C" | "align" => {
                     is_c |= name == "C";
                     if target != Target::Struct &&
@@ -233,7 +233,7 @@ impl<'a, 'tcx> CheckAttrVisitor<'a, 'tcx> {
                 _ => continue,
             };
             self.emit_repr_error(
-                hint.span,
+                hint.span(),
                 item.span,
                 &format!("attribute should be applied to {}", allowed_targets),
                 &format!("not {} {}", article, allowed_targets),
@@ -242,7 +242,7 @@ impl<'a, 'tcx> CheckAttrVisitor<'a, 'tcx> {
 
         // Just point at all repr hints if there are any incompatibilities.
         // This is not ideal, but tracking precisely which ones are at fault is a huge hassle.
-        let hint_spans = hints.iter().map(|hint| hint.span);
+        let hint_spans = hints.iter().map(|hint| hint.span());
 
         // Error on repr(transparent, <anything else>).
         if is_transparent && hints.len() > 1 {
@@ -313,7 +313,7 @@ impl<'a, 'tcx> CheckAttrVisitor<'a, 'tcx> {
 
     fn check_used(&self, item: &hir::Item, target: Target) {
         for attr in &item.attrs {
-            if attr.name() == "used" && target != Target::Static {
+            if attr.check_name("used") && target != Target::Static {
                 self.tcx.sess
                     .span_err(attr.span, "attribute must be applied to a `static` variable");
             }

src/librustc/ich/impls_syntax.rs

@@ -197,7 +197,8 @@ impl<'a> HashStable<StableHashingContext<'a>> for [ast::Attribute] {
         let filtered: SmallVec<[&ast::Attribute; 8]> = self
             .iter()
             .filter(|attr| {
-                !attr.is_sugared_doc && !hcx.is_ignored_attr(attr.name())
+                !attr.is_sugared_doc &&
+                !attr.ident().map_or(false, |ident| hcx.is_ignored_attr(ident.name))
             })
             .collect();
 
@@ -224,7 +225,7 @@ impl<'a> HashStable<StableHashingContext<'a>> for ast::Attribute {
                                           hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         // Make sure that these have been filtered out.
-        debug_assert!(!hcx.is_ignored_attr(self.name()));
+        debug_assert!(!self.ident().map_or(false, |ident| hcx.is_ignored_attr(ident.name)));
         debug_assert!(!self.is_sugared_doc);
 
         let ast::Attribute {
@@ -359,15 +360,13 @@ fn hash_token<'a, 'gcx, W: StableHasherResult>(
     }
 }
 
-impl_stable_hash_for_spanned!(::syntax::ast::NestedMetaItemKind);
-
-impl_stable_hash_for!(enum ::syntax::ast::NestedMetaItemKind {
+impl_stable_hash_for!(enum ::syntax::ast::NestedMetaItem {
     MetaItem(meta_item),
     Literal(lit)
 });
 
 impl_stable_hash_for!(struct ::syntax::ast::MetaItem {
-    ident,
+    path,
     node,
     span
 });

src/librustc/lint/levels.rs

@@ -194,7 +194,7 @@ impl<'a> LintLevelsBuilder<'a> {
             struct_span_err!(sess, span, E0452, "malformed lint attribute")
         };
         for attr in attrs {
-            let level = match Level::from_str(&attr.name().as_str()) {
+            let level = match attr.ident_str().and_then(|name| Level::from_str(name)) {
                 None => continue,
                 Some(lvl) => lvl,
             };
@@ -221,7 +221,7 @@ impl<'a> LintLevelsBuilder<'a> {
                 match item.node {
                     ast::MetaItemKind::Word => {}  // actual lint names handled later
                     ast::MetaItemKind::NameValue(ref name_value) => {
-                        if item.ident == "reason" {
+                        if item.path == "reason" {
                             // found reason, reslice meta list to exclude it
                             metas = &metas[0..metas.len()-1];
                             // FIXME (#55112): issue unused-attributes lint if we thereby
@@ -255,13 +255,13 @@ impl<'a> LintLevelsBuilder<'a> {
             }
 
             for li in metas {
-                let word = match li.word() {
-                    Some(word) => word,
-                    None => {
-                        let mut err = bad_attr(li.span);
+                let meta_item = match li.meta_item() {
+                    Some(meta_item) if meta_item.is_word() => meta_item,
+                    _ => {
+                        let mut err = bad_attr(li.span());
                         if let Some(item) = li.meta_item() {
                             if let ast::MetaItemKind::NameValue(_) = item.node {
-                                if item.ident == "reason" {
+                                if item.path == "reason" {
                                     err.help("reason in lint attribute must come last");
                                 }
                             }
@@ -270,26 +270,27 @@ impl<'a> LintLevelsBuilder<'a> {
                         continue;
                     }
                 };
-                let tool_name = if let Some(lint_tool) = word.is_scoped() {
-                    if !attr::is_known_lint_tool(lint_tool) {
+                let tool_name = if meta_item.path.segments.len() > 1 {
+                    let tool_ident = meta_item.path.segments[0].ident;
+                    if !attr::is_known_lint_tool(tool_ident) {
                         span_err!(
                             sess,
-                            lint_tool.span,
+                            tool_ident.span,
                             E0710,
                             "an unknown tool name found in scoped lint: `{}`",
-                            word.ident
+                            meta_item.path
                         );
                         continue;
                     }
 
-                    Some(lint_tool.as_str())
+                    Some(tool_ident.as_str())
                 } else {
                     None
                 };
-                let name = word.name();
+                let name = meta_item.path.segments.last().expect("empty lint name").ident.name;
                 match store.check_lint_name(&name.as_str(), tool_name) {
                     CheckLintNameResult::Ok(ids) => {
-                        let src = LintSource::Node(name, li.span, reason);
+                        let src = LintSource::Node(name, li.span(), reason);
                         for id in ids {
                             specs.insert(*id, (level, src));
                         }
@@ -300,7 +301,7 @@ impl<'a> LintLevelsBuilder<'a> {
                             Ok(ids) => {
                                 let complete_name = &format!("{}::{}", tool_name.unwrap(), name);
                                 let src = LintSource::Node(
-                                    Symbol::intern(complete_name), li.span, reason
+                                    Symbol::intern(complete_name), li.span(), reason
                                 );
                                 for id in ids {
                                     specs.insert(*id, (level, src));
@@ -322,18 +323,18 @@ impl<'a> LintLevelsBuilder<'a> {
                                     lint,
                                     lvl,
                                     src,
-                                    Some(li.span.into()),
+                                    Some(li.span().into()),
                                     &msg,
                                 );
                                 err.span_suggestion(
-                                    li.span,
+                                    li.span(),
                                     "change it to",
                                     new_lint_name.to_string(),
                                     Applicability::MachineApplicable,
                                 ).emit();
 
                                 let src = LintSource::Node(
-                                    Symbol::intern(&new_lint_name), li.span, reason
+                                    Symbol::intern(&new_lint_name), li.span(), reason
                                 );
                                 for id in ids {
                                     specs.insert(*id, (level, src));
@@ -360,11 +361,11 @@ impl<'a> LintLevelsBuilder<'a> {
                                                               lint,
                                                               level,
                                                               src,
-                                                              Some(li.span.into()),
+                                                              Some(li.span().into()),
                                                               &msg);
                         if let Some(new_name) = renamed {
                             err.span_suggestion(
-                                li.span,
+                                li.span(),
                                 "use the new name",
                                 new_name,
                                 Applicability::MachineApplicable
@@ -383,12 +384,12 @@ impl<'a> LintLevelsBuilder<'a> {
                                                 lint,
                                                 level,
                                                 src,
-                                                Some(li.span.into()),
+                                                Some(li.span().into()),
                                                 &msg);
 
                         if let Some(suggestion) = suggestion {
                             db.span_suggestion(
-                                li.span,
+                                li.span(),
                                 "did you mean",
                                 suggestion.to_string(),
                                 Applicability::MachineApplicable,

src/librustc/lint/mod.rs

@@ -724,7 +724,7 @@ pub fn struct_lint_level<'a>(sess: &'a Session,
 pub fn maybe_lint_level_root(tcx: TyCtxt<'_, '_, '_>, id: hir::HirId) -> bool {
     let attrs = tcx.hir().attrs_by_hir_id(id);
     for attr in attrs {
-        if Level::from_str(&attr.name().as_str()).is_some() {
+        if attr.ident_str().and_then(Level::from_str).is_some() {
             return true;
         }
     }

src/librustc/middle/lib_features.rs

@@ -65,9 +65,9 @@ impl<'a, 'tcx> LibFeatureCollector<'a, 'tcx> {
                 for meta in metas {
                     if let Some(mi) = meta.meta_item() {
                         // Find the `feature = ".."` meta-item.
-                        match (&*mi.name().as_str(), mi.value_str()) {
-                            ("feature", val) => feature = val,
-                            ("since", val) => since = val,
+                        match (mi.ident_str(), mi.value_str()) {
+                            (Some("feature"), val) => feature = val,
+                            (Some("since"), val) => since = val,
                             _ => {}
                         }
                     }

src/librustc/middle/stability.rs

@@ -194,11 +194,12 @@ impl<'a, 'tcx: 'a> Annotator<'a, 'tcx> {
         } else {
             // Emit errors for non-staged-api crates.
             for attr in attrs {
-                let tag = attr.name();
-                if tag == "unstable" || tag == "stable" || tag == "rustc_deprecated" {
-                    attr::mark_used(attr);
-                    self.tcx.sess.span_err(attr.span(), "stability attributes may not be used \
-                                                         outside of the standard library");
+                if let Some(tag) = attr.ident_str() {
+                    if tag == "unstable" || tag == "stable" || tag == "rustc_deprecated" {
+                        attr::mark_used(attr);
+                        self.tcx.sess.span_err(attr.span, "stability attributes may not be used \
+                                                           outside of the standard library");
+                    }
                 }
             }
 

src/librustc/session/config.rs

@@ -1839,7 +1839,7 @@ pub fn parse_cfgspecs(cfgspecs: Vec<String>) -> FxHashSet<(String, Option<String
 
             match &mut parser.parse_meta_item() {
                 Ok(meta_item) if parser.token == token::Eof => {
-                    if meta_item.ident.segments.len() != 1 {
+                    if meta_item.path.segments.len() != 1 {
                         error!("argument key must be an identifier");
                     }
                     match &meta_item.node {
@@ -1850,7 +1850,8 @@ pub fn parse_cfgspecs(cfgspecs: Vec<String>) -> FxHashSet<(String, Option<String
                             error!("argument value must be a string");
                         }
                         MetaItemKind::NameValue(..) | MetaItemKind::Word => {
-                            return (meta_item.name(), meta_item.value_str());
+                            let ident = meta_item.ident().expect("multi-segment cfg key");
+                            return (ident.name, meta_item.value_str());
                         }
                     }
                 }

src/librustc/traits/on_unimplemented.rs

@@ -107,7 +107,7 @@ impl<'a, 'gcx, 'tcx> OnUnimplementedDirective {
             {
                 if let Some(items) = item.meta_item_list() {
                     if let Ok(subcommand) =
-                        Self::parse(tcx, trait_def_id, &items, item.span, false)
+                        Self::parse(tcx, trait_def_id, &items, item.span(), false)
                     {
                         subcommands.push(subcommand);
                     } else {
@@ -118,7 +118,7 @@ impl<'a, 'gcx, 'tcx> OnUnimplementedDirective {
             }
 
             // nothing found
-            parse_error(tcx, item.span,
+            parse_error(tcx, item.span(),
                         "this attribute must have a valid value",
                         "expected value here",
                         Some(r#"eg `#[rustc_on_unimplemented(message="foo")]`"#));
@@ -177,10 +177,12 @@ impl<'a, 'gcx, 'tcx> OnUnimplementedDirective {
         for command in self.subcommands.iter().chain(Some(self)).rev() {
             if let Some(ref condition) = command.condition {
                 if !attr::eval_condition(condition, &tcx.sess.parse_sess, &mut |c| {
-                    options.contains(&(
-                        c.name().as_str().to_string(),
-                        c.value_str().map(|s| s.as_str().to_string())
-                    ))
+                    c.ident_str().map_or(false, |name| {
+                        options.contains(&(
+                            name.to_string(),
+                            c.value_str().map(|s| s.as_str().to_string())
+                        ))
+                    })
                 }) {
                     debug!("evaluate: skipping {:?} due to condition", command);
                     continue

src/librustc_driver/lib.rs

@@ -683,7 +683,7 @@ impl RustcDefaultCalls {
 
                     let mut cfgs = sess.parse_sess.config.iter().filter_map(|&(name, ref value)| {
                         let gated_cfg = GatedCfg::gate(&ast::MetaItem {
-                            ident: ast::Path::from_ident(ast::Ident::with_empty_ctxt(name)),
+                            path: ast::Path::from_ident(ast::Ident::with_empty_ctxt(name)),
                             node: ast::MetaItemKind::Word,
                             span: DUMMY_SP,
                         });

src/librustc_incremental/assert_dep_graph.rs

@@ -99,12 +99,12 @@ impl<'a, 'tcx> IfThisChanged<'a, 'tcx> {
     fn argument(&self, attr: &ast::Attribute) -> Option<ast::Name> {
         let mut value = None;
         for list_item in attr.meta_item_list().unwrap_or_default() {
-            match list_item.word() {
-                Some(word) if value.is_none() =>
-                    value = Some(word.name()),
+            match list_item.ident() {
+                Some(ident) if list_item.is_word() && value.is_none() =>
+                    value = Some(ident.name),
                 _ =>
                     // FIXME better-encapsulate meta_item (don't directly access `node`)
-                    span_bug!(list_item.span(), "unexpected meta-item {:?}", list_item.node),
+                    span_bug!(list_item.span(), "unexpected meta-item {:?}", list_item),
             }
         }
         value

src/librustc_incremental/assert_module_sources.rs

@@ -153,7 +153,7 @@ impl<'a, 'tcx> AssertModuleSource<'a, 'tcx> {
                     return value;
                 } else {
                     self.tcx.sess.span_fatal(
-                        item.span,
+                        item.span(),
                         &format!("associated value expected for `{}`", name));
                 }
             }

src/librustc_incremental/persist/dirty_clean.rs

@@ -430,13 +430,13 @@ impl<'a, 'tcx> DirtyCleanVisitor<'a, 'tcx> {
             if DepNode::has_label_string(label) {
                 if out.contains(label) {
                     self.tcx.sess.span_fatal(
-                        item.span,
+                        item.span(),
                         &format!("dep-node label `{}` is repeated", label));
                 }
                 out.insert(label.to_string());
             } else {
                 self.tcx.sess.span_fatal(
-                    item.span,
+                    item.span(),
                     &format!("dep-node label `{}` not recognized", label));
             }
         }
@@ -576,13 +576,13 @@ fn expect_associated_value(tcx: TyCtxt<'_, '_, '_>, item: &NestedMetaItem) -> as
     if let Some(value) = item.value_str() {
         value
     } else {
-        let msg = if let Some(name) = item.name() {
+        let msg = if let Some(name) = item.ident_str() {
             format!("associated value expected for `{}`", name)
         } else {
             "expected an associated value".to_string()
         };
 
-        tcx.sess.span_fatal(item.span, &msg);
+        tcx.sess.span_fatal(item.span(), &msg);
     }
 }