Rename kw::Invalid -> kw::Empty

See https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/Is.20there.20a.20symbol.20for.20the.20empty.20string.3F/near/220054471
for context.

compiler/rustc_ast_lowering/src/lib.rs

@@ -1716,7 +1716,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         }
         self.arena.alloc_from_iter(inputs.iter().map(|param| match param.pat.kind {
             PatKind::Ident(_, ident, _) => ident,
-            _ => Ident::new(kw::Invalid, param.pat.span),
+            _ => Ident::new(kw::Empty, param.pat.span),
         }))
     }
 

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -184,7 +184,7 @@ impl<'a> AstValidator<'a> {
     }
 
     fn check_lifetime(&self, ident: Ident) {
-        let valid_names = [kw::UnderscoreLifetime, kw::StaticLifetime, kw::Invalid];
+        let valid_names = [kw::UnderscoreLifetime, kw::StaticLifetime, kw::Empty];
         if !valid_names.contains(&ident.name) && ident.without_first_quote().is_reserved() {
             self.err_handler().span_err(ident.span, "lifetimes cannot use keyword names");
         }

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -2787,7 +2787,7 @@ impl<'a> State<'a> {
                     self.print_explicit_self(&eself);
                 } else {
                     let invalid = if let PatKind::Ident(_, ident, _) = input.pat.kind {
-                        ident.name == kw::Invalid
+                        ident.name == kw::Empty
                     } else {
                         false
                     };

compiler/rustc_builtin_macros/src/llvm_asm.rs

@@ -93,7 +93,7 @@ fn parse_inline_asm<'a>(
         })
         .unwrap_or(tts.len());
     let mut p = cx.new_parser_from_tts(tts.trees().skip(first_colon).collect());
-    let mut asm = kw::Invalid;
+    let mut asm = kw::Empty;
     let mut asm_str_style = None;
     let mut outputs = Vec::new();
     let mut inputs = Vec::new();

compiler/rustc_codegen_ssa/src/mir/debuginfo.rs

@@ -170,7 +170,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 // (after #67586 gets fixed).
                 None
             } else {
-                let name = kw::Invalid;
+                let name = kw::Empty;
                 let decl = &self.mir.local_decls[local];
                 let dbg_var = if full_debug_info {
                     self.adjusted_span_and_dbg_scope(decl.source_info).map(
@@ -204,7 +204,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             None
         } else {
             Some(match whole_local_var.or(fallback_var) {
-                Some(var) if var.name != kw::Invalid => var.name.to_string(),
+                Some(var) if var.name != kw::Empty => var.name.to_string(),
                 _ => format!("{:?}", local),
             })
         };

compiler/rustc_hir/src/hir.rs

@@ -28,7 +28,7 @@ pub struct Lifetime {
     pub span: Span,
 
     /// Either "`'a`", referring to a named lifetime definition,
-    /// or "``" (i.e., `kw::Invalid`), for elision placeholders.
+    /// or "``" (i.e., `kw::Empty`), for elision placeholders.
     ///
     /// HIR lowering inserts these placeholders in type paths that
     /// refer to type definitions needing lifetime parameters,

compiler/rustc_lint/src/builtin.rs

@@ -868,7 +868,7 @@ impl EarlyLintPass for AnonymousParameters {
         if let ast::AssocItemKind::Fn(_, ref sig, _, _) = it.kind {
             for arg in sig.decl.inputs.iter() {
                 if let ast::PatKind::Ident(_, ident, None) = arg.pat.kind {
-                    if ident.name == kw::Invalid {
+                    if ident.name == kw::Empty {
                         cx.struct_span_lint(ANONYMOUS_PARAMETERS, arg.pat.span, |lint| {
                             let ty_snip = cx.sess.source_map().span_to_snippet(arg.ty.span);
 

compiler/rustc_lint/src/context.rs

@@ -728,7 +728,7 @@ impl<'tcx> LateContext<'tcx> {
 
     /// Check if a `DefId`'s path matches the given absolute type path usage.
     ///
-    /// Anonymous scopes such as `extern` imports are matched with `kw::Invalid`;
+    /// Anonymous scopes such as `extern` imports are matched with `kw::Empty`;
     /// inherent `impl` blocks are matched with the name of the type.
     ///
     /// Instead of using this method, it is often preferable to instead use

compiler/rustc_metadata/src/native_libs.rs

@@ -132,7 +132,7 @@ impl ItemLikeVisitor<'tcx> for Collector<'tcx> {
 
 impl Collector<'tcx> {
     fn register_native_lib(&mut self, span: Option<Span>, lib: NativeLib) {
-        if lib.name.as_ref().map(|&s| s == kw::Invalid).unwrap_or(false) {
+        if lib.name.as_ref().map(|&s| s == kw::Empty).unwrap_or(false) {
             match span {
                 Some(span) => {
                     struct_span_err!(

compiler/rustc_middle/src/hir/map/mod.rs

@@ -379,7 +379,7 @@ impl<'hir> Map<'hir> {
     pub fn body_param_names(&self, id: BodyId) -> impl Iterator<Item = Ident> + 'hir {
         self.body(id).params.iter().map(|arg| match arg.pat.kind {
             PatKind::Binding(_, _, ident, _) => ident,
-            _ => Ident::new(kw::Invalid, rustc_span::DUMMY_SP),
+            _ => Ident::new(kw::Empty, rustc_span::DUMMY_SP),
         })
     }
 

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -1481,7 +1481,7 @@ impl<F: fmt::Write> Printer<'tcx> for FmtPrinter<'_, 'tcx, F> {
         // FIXME(eddyb) `name` should never be empty, but it
         // currently is for `extern { ... }` "foreign modules".
         let name = disambiguated_data.data.name();
-        if name != DefPathDataName::Named(kw::Invalid) {
+        if name != DefPathDataName::Named(kw::Empty) {
             if !self.empty_path {
                 write!(self, "::")?;
             }
@@ -1608,14 +1608,14 @@ impl<F: fmt::Write> PrettyPrinter<'tcx> for FmtPrinter<'_, 'tcx, F> {
 
         match *region {
             ty::ReEarlyBound(ref data) => {
-                data.name != kw::Invalid && data.name != kw::UnderscoreLifetime
+                data.name != kw::Empty && data.name != kw::UnderscoreLifetime
             }
 
             ty::ReLateBound(_, ty::BoundRegion { kind: br })
             | ty::ReFree(ty::FreeRegion { bound_region: br, .. })
             | ty::RePlaceholder(ty::Placeholder { name: br, .. }) => {
                 if let ty::BrNamed(_, name) = br {
-                    if name != kw::Invalid && name != kw::UnderscoreLifetime {
+                    if name != kw::Empty && name != kw::UnderscoreLifetime {
                         return true;
                     }
                 }
@@ -1685,7 +1685,7 @@ impl<F: fmt::Write> FmtPrinter<'_, '_, F> {
         // `explain_region()` or `note_and_explain_region()`.
         match *region {
             ty::ReEarlyBound(ref data) => {
-                if data.name != kw::Invalid {
+                if data.name != kw::Empty {
                     p!(write("{}", data.name));
                     return Ok(self);
                 }
@@ -1694,7 +1694,7 @@ impl<F: fmt::Write> FmtPrinter<'_, '_, F> {
             | ty::ReFree(ty::FreeRegion { bound_region: br, .. })
             | ty::RePlaceholder(ty::Placeholder { name: br, .. }) => {
                 if let ty::BrNamed(_, name) = br {
-                    if name != kw::Invalid && name != kw::UnderscoreLifetime {
+                    if name != kw::Empty && name != kw::UnderscoreLifetime {
                         p!(write("{}", name));
                         return Ok(self);
                     }

compiler/rustc_mir_build/src/build/mod.rs

@@ -854,7 +854,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     let mut mutability = Mutability::Not;
 
                     // FIXME(project-rfc-2229#8): Store more precise information
-                    let mut name = kw::Invalid;
+                    let mut name = kw::Empty;
                     if let Some(Node::Binding(pat)) = tcx_hir.find(var_id) {
                         if let hir::PatKind::Binding(_, _, ident, _) = pat.kind {
                             name = ident.name;

compiler/rustc_parse/src/parser/item.rs

@@ -494,7 +494,7 @@ impl<'a> Parser<'a> {
         let polarity = self.parse_polarity();
 
         // Parse both types and traits as a type, then reinterpret if necessary.
-        let err_path = |span| ast::Path::from_ident(Ident::new(kw::Invalid, span));
+        let err_path = |span| ast::Path::from_ident(Ident::new(kw::Empty, span));
         let ty_first = if self.token.is_keyword(kw::For) && self.look_ahead(1, |t| t != &token::Lt)
         {
             let span = self.prev_token.span.between(self.token.span);
@@ -1699,7 +1699,7 @@ impl<'a> Parser<'a> {
                 // Skip every token until next possible arg or end.
                 p.eat_to_tokens(&[&token::Comma, &token::CloseDelim(token::Paren)]);
                 // Create a placeholder argument for proper arg count (issue #34264).
-                Ok(dummy_arg(Ident::new(kw::Invalid, lo.to(p.prev_token.span))))
+                Ok(dummy_arg(Ident::new(kw::Empty, lo.to(p.prev_token.span))))
             });
             // ...now that we've parsed the first argument, `self` is no longer allowed.
             first_param = false;
@@ -1759,7 +1759,7 @@ impl<'a> Parser<'a> {
             }
             match ty {
                 Ok(ty) => {
-                    let ident = Ident::new(kw::Invalid, self.prev_token.span);
+                    let ident = Ident::new(kw::Empty, self.prev_token.span);
                     let bm = BindingMode::ByValue(Mutability::Not);
                     let pat = self.mk_pat_ident(ty.span, bm, ident);
                     (pat, ty)

compiler/rustc_passes/src/liveness.rs

@@ -1385,7 +1385,7 @@ impl<'tcx> Liveness<'_, 'tcx> {
 
     fn should_warn(&self, var: Variable) -> Option<String> {
         let name = self.ir.variable_name(var);
-        if name == kw::Invalid {
+        if name == kw::Empty {
             return None;
         }
         let name: &str = &name.as_str();

compiler/rustc_privacy/src/lib.rs

@@ -959,7 +959,7 @@ impl<'tcx> NamePrivacyVisitor<'tcx> {
         in_update_syntax: bool,
     ) {
         // definition of the field
-        let ident = Ident::new(kw::Invalid, use_ctxt);
+        let ident = Ident::new(kw::Empty, use_ctxt);
         let current_hir = self.current_item.unwrap();
         let def_id = self.tcx.adjust_ident_and_get_scope(ident, def.did, current_hir).1;
         if !def.is_enum() && !field.vis.is_accessible_from(def_id, self.tcx) {

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -342,7 +342,7 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
         let field_names = vdata
             .fields()
             .iter()
-            .map(|field| respan(field.span, field.ident.map_or(kw::Invalid, |ident| ident.name)))
+            .map(|field| respan(field.span, field.ident.map_or(kw::Empty, |ident| ident.name)))
             .collect();
         self.insert_field_names(def_id, field_names);
     }
@@ -527,7 +527,7 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
                         // HACK(eddyb) unclear how good this is, but keeping `$crate`
                         // in `source` breaks `src/test/compile-fail/import-crate-var.rs`,
                         // while the current crate doesn't have a valid `crate_name`.
-                        if crate_name != kw::Invalid {
+                        if crate_name != kw::Empty {
                             // `crate_name` should not be interpreted as relative.
                             module_path.push(Segment {
                                 ident: Ident { name: kw::PathRoot, span: source.ident.span },
@@ -656,7 +656,7 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
 
     /// Constructs the reduced graph for one item.
     fn build_reduced_graph_for_item(&mut self, item: &'b Item) {
-        if matches!(item.kind, ItemKind::Mod(..)) && item.ident.name == kw::Invalid {
+        if matches!(item.kind, ItemKind::Mod(..)) && item.ident.name == kw::Empty {
             // Fake crate root item from expand.
             return;
         }

compiler/rustc_resolve/src/def_collector.rs

@@ -74,7 +74,7 @@ impl<'a, 'b> visit::Visitor<'a> for DefCollector<'a, 'b> {
         // information we encapsulate into, the better
         let def_data = match &i.kind {
             ItemKind::Impl { .. } => DefPathData::Impl,
-            ItemKind::Mod(..) if i.ident.name == kw::Invalid => {
+            ItemKind::Mod(..) if i.ident.name == kw::Empty => {
                 // Fake crate root item from expand.
                 return visit::walk_item(self, i);
             }

compiler/rustc_resolve/src/late.rs

@@ -1641,7 +1641,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
         }
 
         // Record as bound if it's valid:
-        let ident_valid = ident.name != kw::Invalid;
+        let ident_valid = ident.name != kw::Empty;
         if ident_valid {
             bindings.last_mut().unwrap().1.insert(ident);
         }

compiler/rustc_resolve/src/lib.rs

@@ -1182,12 +1182,12 @@ impl<'a> Resolver<'a> {
     ) -> Resolver<'a> {
         let root_local_def_id = LocalDefId { local_def_index: CRATE_DEF_INDEX };
         let root_def_id = root_local_def_id.to_def_id();
-        let root_module_kind = ModuleKind::Def(DefKind::Mod, root_def_id, kw::Invalid);
+        let root_module_kind = ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty);
         let graph_root = arenas.alloc_module(ModuleData {
             no_implicit_prelude: session.contains_name(&krate.attrs, sym::no_implicit_prelude),
             ..ModuleData::new(None, root_module_kind, root_def_id, ExpnId::root(), krate.span)
         });
-        let empty_module_kind = ModuleKind::Def(DefKind::Mod, root_def_id, kw::Invalid);
+        let empty_module_kind = ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty);
         let empty_module = arenas.alloc_module(ModuleData {
             no_implicit_prelude: true,
             ..ModuleData::new(
@@ -1797,7 +1797,7 @@ impl<'a> Resolver<'a> {
         ribs: &[Rib<'a>],
     ) -> Option<LexicalScopeBinding<'a>> {
         assert!(ns == TypeNS || ns == ValueNS);
-        if ident.name == kw::Invalid {
+        if ident.name == kw::Empty {
             return Some(LexicalScopeBinding::Res(Res::Err));
         }
         let (general_span, normalized_span) = if ident.name == kw::SelfUpper {

compiler/rustc_resolve/src/macros.rs

@@ -160,7 +160,7 @@ impl<'a> ResolverExpand for Resolver<'a> {
         hygiene::update_dollar_crate_names(|ctxt| {
             let ident = Ident::new(kw::DollarCrate, DUMMY_SP.with_ctxt(ctxt));
             match self.resolve_crate_root(ident).kind {
-                ModuleKind::Def(.., name) if name != kw::Invalid => name,
+                ModuleKind::Def(.., name) if name != kw::Empty => name,
                 _ => kw::Crate,
             }
         });

compiler/rustc_span/src/hygiene.rs

@@ -1065,7 +1065,7 @@ pub fn decode_syntax_context<
             parent: SyntaxContext::root(),
             opaque: SyntaxContext::root(),
             opaque_and_semitransparent: SyntaxContext::root(),
-            dollar_crate_name: kw::Invalid,
+            dollar_crate_name: kw::Empty,
         });
         let mut ctxts = outer_ctxts.lock();
         let new_len = raw_id as usize + 1;
@@ -1092,7 +1092,7 @@ pub fn decode_syntax_context<
             ctxt_data,
         );
         // Make sure nothing weird happening while `decode_data` was running
-        assert_eq!(dummy.dollar_crate_name, kw::Invalid);
+        assert_eq!(dummy.dollar_crate_name, kw::Empty);
     });
 
     Ok(new_ctxt)

compiler/rustc_span/src/symbol.rs

@@ -25,7 +25,7 @@ symbols! {
     Keywords {
         // Special reserved identifiers used internally for elided lifetimes,
         // unnamed method parameters, crate root module, error recovery etc.
-        Invalid:            "",
+        Empty:              "",
         PathRoot:           "{{root}}",
         DollarCrate:        "$crate",
         Underscore:         "_",
@@ -1273,7 +1273,7 @@ impl Ident {
 
     #[inline]
     pub fn invalid() -> Ident {
-        Ident::with_dummy_span(kw::Invalid)
+        Ident::with_dummy_span(kw::Empty)
     }
 
     /// Maps a string to an identifier with a dummy span.
@@ -1470,7 +1470,7 @@ impl Symbol {
     }
 
     pub fn is_empty(self) -> bool {
-        self == kw::Invalid
+        self == kw::Empty
     }
 
     /// This method is supposed to be used in error messages, so it's expected to be
@@ -1654,7 +1654,7 @@ impl Symbol {
 
     /// Returns `true` if this symbol can be a raw identifier.
     pub fn can_be_raw(self) -> bool {
-        self != kw::Invalid && self != kw::Underscore && !self.is_path_segment_keyword()
+        self != kw::Empty && self != kw::Underscore && !self.is_path_segment_keyword()
     }
 }
 

compiler/rustc_typeck/src/check/expr.rs

@@ -883,7 +883,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 Ok(method)
             }
             Err(error) => {
-                if segment.ident.name != kw::Invalid {
+                if segment.ident.name != kw::Empty {
                     self.report_extended_method_error(segment, span, args, rcvr_t, error);
                 }
                 Err(())
@@ -1547,7 +1547,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             return field_ty;
         }
 
-        if field.name == kw::Invalid {
+        if field.name == kw::Empty {
         } else if self.method_exists(field, expr_t, expr.hir_id, true) {
             self.ban_take_value_of_method(expr, expr_t, field);
         } else if !expr_t.is_primitive_ty() {

compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs

@@ -914,7 +914,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 method::MethodError::PrivateMatch(kind, def_id, _) => Ok((kind, def_id)),
                 _ => Err(ErrorReported),
             };
-            if item_name.name != kw::Invalid {
+            if item_name.name != kw::Empty {
                 if let Some(mut e) = self.report_method_error(
                     span,
                     ty,

src/librustdoc/clean/mod.rs

@@ -941,7 +941,7 @@ impl<'a> Clean<Arguments> for (&'a [hir::Ty<'a>], &'a [Ident]) {
                 .iter()
                 .enumerate()
                 .map(|(i, ty)| {
-                    let mut name = self.1.get(i).map(|ident| ident.name).unwrap_or(kw::Invalid);
+                    let mut name = self.1.get(i).map(|ident| ident.name).unwrap_or(kw::Empty);
                     if name.is_empty() {
                         name = kw::Underscore;
                     }
@@ -1000,7 +1000,7 @@ impl<'tcx> Clean<FnDecl> for (DefId, ty::PolyFnSig<'tcx>) {
                     .iter()
                     .map(|t| Argument {
                         type_: t.clean(cx),
-                        name: names.next().map(|i| i.name).unwrap_or(kw::Invalid),
+                        name: names.next().map(|i| i.name).unwrap_or(kw::Empty),
                     })
                     .collect(),
             },

src/librustdoc/html/render/mod.rs

@@ -2086,8 +2086,8 @@ fn item_module(w: &mut Buffer, cx: &Context<'_>, item: &clean::Item, items: &[cl
                 (true, false) => return Ordering::Greater,
             }
         }
-        let lhs = i1.name.unwrap_or(kw::Invalid).as_str();
+        let lhs = i1.name.unwrap_or(kw::Empty).as_str();
-        let rhs = i2.name.unwrap_or(kw::Invalid).as_str();
+        let rhs = i2.name.unwrap_or(kw::Empty).as_str();
         compare_names(&lhs, &rhs)
     }
 
@@ -4206,7 +4206,7 @@ fn print_sidebar(cx: &Context<'_>, it: &clean::Item, buffer: &mut Buffer, cache:
                 ty: \"{ty}\", \
                 relpath: \"{path}\"\
             }};</script>",
-        name = it.name.unwrap_or(kw::Invalid),
+        name = it.name.unwrap_or(kw::Empty),
         ty = it.type_(),
         path = relpath
     );

src/tools/clippy/clippy_lints/src/lifetimes.rs

@@ -501,7 +501,7 @@ impl<'tcx> Visitor<'tcx> for BodyLifetimeChecker {
 
     // for lifetimes as parameters of generics
     fn visit_lifetime(&mut self, lifetime: &'tcx Lifetime) {
-        if lifetime.name.ident().name != kw::Invalid && lifetime.name.ident().name != kw::StaticLifetime {
+        if lifetime.name.ident().name != kw::Empty && lifetime.name.ident().name != kw::StaticLifetime {
             self.lifetimes_used_in_body = true;
         }
     }