Auto merge of #60740 - petrochenkov:kw, r=nnethercote

Simplify use of keyword symbols

They mirror non-keyword symbols now (see #60630).

`keywords::MyKeyword.name()` -> `kw::MyKeyword`
`keywords::MyKeyword.ident()` -> `Ident::with_empty_ctxt(kw::MyKeyword)` (not common)
`keywords::Invalid.ident()` -> `Ident::invalid()` (more common)

Keywords are simply `Symbol` constants now, the `Keyword` struct is eliminated.
This means `kw::MyKeyword` can now be used in `match` in particular.

src/librustc/hir/lowering.rs

@@ -64,7 +64,7 @@ use syntax::ptr::P;
 use syntax::source_map::{respan, CompilerDesugaringKind, Spanned};
 use syntax::source_map::CompilerDesugaringKind::IfTemporary;
 use syntax::std_inject;
-use syntax::symbol::{keywords, Symbol, sym};
+use syntax::symbol::{kw, sym, Symbol};
 use syntax::tokenstream::{TokenStream, TokenTree};
 use syntax::parse::token::Token;
 use syntax::visit::{self, Visitor};
@@ -926,11 +926,11 @@ impl<'a> LoweringContext<'a> {
                 hir::LifetimeParamKind::InBand,
             ),
             ParamName::Fresh(_) => (
-                keywords::UnderscoreLifetime.name().as_interned_str(),
+                kw::UnderscoreLifetime.as_interned_str(),
                 hir::LifetimeParamKind::Elided,
             ),
             ParamName::Error => (
-                keywords::UnderscoreLifetime.name().as_interned_str(),
+                kw::UnderscoreLifetime.as_interned_str(),
                 hir::LifetimeParamKind::Error,
             ),
         };
@@ -1414,7 +1414,7 @@ impl<'a> LoweringContext<'a> {
                     P(hir::Path {
                         res,
                         segments: hir_vec![hir::PathSegment::from_ident(
-                            keywords::SelfUpper.ident()
+                            Ident::with_empty_ctxt(kw::SelfUpper)
                         )],
                         span: t.span,
                     }),
@@ -1613,7 +1613,7 @@ impl<'a> LoweringContext<'a> {
         trace!("registering existential type with id {:#?}", exist_ty_id);
         let exist_ty_item = hir::Item {
             hir_id: exist_ty_id,
-            ident: keywords::Invalid.ident(),
+            ident: Ident::invalid(),
             attrs: Default::default(),
             node: exist_ty_item_kind,
             vis: respan(span.shrink_to_lo(), hir::VisibilityKind::Inherited),
@@ -1746,7 +1746,7 @@ impl<'a> LoweringContext<'a> {
 
                     let (name, kind) = match name {
                         hir::LifetimeName::Underscore => (
-                            hir::ParamName::Plain(keywords::UnderscoreLifetime.ident()),
+                            hir::ParamName::Plain(Ident::with_empty_ctxt(kw::UnderscoreLifetime)),
                             hir::LifetimeParamKind::Elided,
                         ),
                         hir::LifetimeName::Param(param_name) => (
@@ -2295,7 +2295,7 @@ impl<'a> LoweringContext<'a> {
             .iter()
             .map(|arg| match arg.pat.node {
                 PatKind::Ident(_, ident, _) => ident,
-                _ => Ident::new(keywords::Invalid.name(), arg.pat.span),
+                _ => Ident::new(kw::Invalid, arg.pat.span),
             })
             .collect()
     }
@@ -2584,9 +2584,9 @@ impl<'a> LoweringContext<'a> {
     fn lower_lifetime(&mut self, l: &Lifetime) -> hir::Lifetime {
         let span = l.ident.span;
         match l.ident {
-            ident if ident.name == keywords::StaticLifetime.name() =>
+            ident if ident.name == kw::StaticLifetime =>
                 self.new_named_lifetime(l.id, span, hir::LifetimeName::Static),
-            ident if ident.name == keywords::UnderscoreLifetime.name() =>
+            ident if ident.name == kw::UnderscoreLifetime =>
                 match self.anonymous_lifetime_mode {
                     AnonymousLifetimeMode::CreateParameter => {
                         let fresh_name = self.collect_fresh_in_band_lifetime(span);
@@ -2708,7 +2708,7 @@ impl<'a> LoweringContext<'a> {
                 // Don't expose `Self` (recovered "keyword used as ident" parse error).
                 // `rustc::ty` expects `Self` to be only used for a trait's `Self`.
                 // Instead, use `gensym("Self")` to create a distinct name that looks the same.
-                let ident = if param.ident.name == keywords::SelfUpper.name() {
+                let ident = if param.ident.name == kw::SelfUpper {
                     param.ident.gensym()
                 } else {
                     param.ident
@@ -3323,7 +3323,7 @@ impl<'a> LoweringContext<'a> {
 
                 // Correctly resolve `self` imports.
                 if path.segments.len() > 1
-                    && path.segments.last().unwrap().ident.name == keywords::SelfLower.name()
+                    && path.segments.last().unwrap().ident.name == kw::SelfLower
                 {
                     let _ = path.segments.pop();
                     if rename.is_none() {

src/librustc/hir/map/def_collector.rs

@@ -5,7 +5,7 @@ use crate::session::CrateDisambiguator;
 use syntax::ast::*;
 use syntax::ext::hygiene::Mark;
 use syntax::visit;
-use syntax::symbol::keywords;
+use syntax::symbol::kw;
 use syntax::symbol::Symbol;
 use syntax::parse::token::{self, Token};
 use syntax_pos::Span;
@@ -138,7 +138,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
         // information we encapsulate into, the better
         let def_data = match i.node {
             ItemKind::Impl(..) => DefPathData::Impl,
-            ItemKind::Mod(..) if i.ident == keywords::Invalid.ident() => {
+            ItemKind::Mod(..) if i.ident.name == kw::Invalid => {
                 return visit::walk_item(self, i);
             }
             ItemKind::Mod(..) | ItemKind::Trait(..) | ItemKind::TraitAlias(..) |

src/librustc/hir/map/mod.rs

@@ -519,7 +519,7 @@ impl<'hir> Map<'hir> {
     pub fn ty_param_name(&self, id: HirId) -> Name {
         match self.get_by_hir_id(id) {
             Node::Item(&Item { node: ItemKind::Trait(..), .. }) |
-            Node::Item(&Item { node: ItemKind::TraitAlias(..), .. }) => keywords::SelfUpper.name(),
+            Node::Item(&Item { node: ItemKind::TraitAlias(..), .. }) => kw::SelfUpper,
             Node::GenericParam(param) => param.name.ident().name,
             _ => bug!("ty_param_name: {} not a type parameter", self.hir_to_string(id)),
         }

src/librustc/hir/mod.rs

@@ -24,7 +24,7 @@ use syntax::ast::{Attribute, Label, LitKind, StrStyle, FloatTy, IntTy, UintTy};
 use syntax::attr::{InlineAttr, OptimizeAttr};
 use syntax::ext::hygiene::SyntaxContext;
 use syntax::ptr::P;
-use syntax::symbol::{Symbol, keywords};
+use syntax::symbol::{Symbol, kw};
 use syntax::tokenstream::TokenStream;
 use syntax::util::parser::ExprPrecedence;
 use crate::ty::AdtKind;
@@ -160,7 +160,7 @@ pub struct Lifetime {
     pub span: Span,
 
     /// Either "`'a`", referring to a named lifetime definition,
-    /// or "``" (i.e., `keywords::Invalid`), for elision placeholders.
+    /// or "``" (i.e., `kw::Invalid`), for elision placeholders.
     ///
     /// HIR lowering inserts these placeholders in type paths that
     /// refer to type definitions needing lifetime parameters,
@@ -199,7 +199,8 @@ impl ParamName {
     pub fn ident(&self) -> Ident {
         match *self {
             ParamName::Plain(ident) => ident,
-            ParamName::Error | ParamName::Fresh(_) => keywords::UnderscoreLifetime.ident(),
+            ParamName::Fresh(_) |
+            ParamName::Error => Ident::with_empty_ctxt(kw::UnderscoreLifetime),
         }
     }
 
@@ -233,10 +234,9 @@ pub enum LifetimeName {
 impl LifetimeName {
     pub fn ident(&self) -> Ident {
         match *self {
-            LifetimeName::Implicit => keywords::Invalid.ident(),
-            LifetimeName::Error => keywords::Invalid.ident(),
-            LifetimeName::Underscore => keywords::UnderscoreLifetime.ident(),
-            LifetimeName::Static => keywords::StaticLifetime.ident(),
+            LifetimeName::Implicit | LifetimeName::Error => Ident::invalid(),
+            LifetimeName::Underscore => Ident::with_empty_ctxt(kw::UnderscoreLifetime),
+            LifetimeName::Static => Ident::with_empty_ctxt(kw::StaticLifetime),
             LifetimeName::Param(param_name) => param_name.ident(),
         }
     }
@@ -305,7 +305,7 @@ pub struct Path {
 
 impl Path {
     pub fn is_global(&self) -> bool {
-        !self.segments.is_empty() && self.segments[0].ident.name == keywords::PathRoot.name()
+        !self.segments.is_empty() && self.segments[0].ident.name == kw::PathRoot
     }
 }
 

src/librustc/hir/print.rs

@@ -7,7 +7,7 @@ use syntax::print::pp::{self, Breaks};
 use syntax::print::pp::Breaks::{Consistent, Inconsistent};
 use syntax::print::pprust::{self, PrintState};
 use syntax::ptr::P;
-use syntax::symbol::keywords;
+use syntax::symbol::kw;
 use syntax::util::parser::{self, AssocOp, Fixity};
 use syntax_pos::{self, BytePos, FileName};
 
@@ -798,7 +798,7 @@ impl<'a> State<'a> {
             hir::VisibilityKind::Restricted { ref path, .. } => {
                 self.s.word("pub(")?;
                 if path.segments.len() == 1 &&
-                   path.segments[0].ident.name == keywords::Super.name() {
+                   path.segments[0].ident.name == kw::Super {
                     // Special case: `super` can print like `pub(super)`.
                     self.s.word("super")?;
                 } else {
@@ -1559,7 +1559,7 @@ impl<'a> State<'a> {
             if i > 0 {
                 self.s.word("::")?
             }
-            if segment.ident.name != keywords::PathRoot.name() {
+            if segment.ident.name != kw::PathRoot {
                self.print_ident(segment.ident)?;
                segment.with_generic_args(|generic_args| {
                    self.print_generic_args(generic_args, segment.infer_types,
@@ -1572,7 +1572,7 @@ impl<'a> State<'a> {
     }
 
     pub fn print_path_segment(&mut self, segment: &hir::PathSegment) -> io::Result<()> {
-        if segment.ident.name != keywords::PathRoot.name() {
+        if segment.ident.name != kw::PathRoot {
            self.print_ident(segment.ident)?;
            segment.with_generic_args(|generic_args| {
                self.print_generic_args(generic_args, segment.infer_types, false)
@@ -1599,7 +1599,7 @@ impl<'a> State<'a> {
                     if i > 0 {
                         self.s.word("::")?
                     }
-                    if segment.ident.name != keywords::PathRoot.name() {
+                    if segment.ident.name != kw::PathRoot {
                         self.print_ident(segment.ident)?;
                         segment.with_generic_args(|generic_args| {
                             self.print_generic_args(generic_args,

src/librustc/middle/liveness.rs

@@ -112,7 +112,7 @@ use std::io;
 use std::rc::Rc;
 use syntax::ast::{self, NodeId};
 use syntax::ptr::P;
-use syntax::symbol::{keywords, sym};
+use syntax::symbol::{kw, sym};
 use syntax_pos::Span;
 
 use crate::hir;
@@ -1552,7 +1552,7 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
                 let sp = ident.span;
                 let var = self.variable(hir_id, sp);
                 // Ignore unused self.
-                if ident.name != keywords::SelfLower.name() {
+                if ident.name != kw::SelfLower {
                     if !self.warn_about_unused(vec![sp], hir_id, entry_ln, var) {
                         if self.live_on_entry(entry_ln, var).is_none() {
                             self.report_dead_assign(hir_id, sp, var, true);

src/librustc/middle/resolve_lifetime.rs

@@ -23,7 +23,7 @@ use std::mem::replace;
 use syntax::ast;
 use syntax::attr;
 use syntax::ptr::P;
-use syntax::symbol::{keywords, sym};
+use syntax::symbol::{kw, sym};
 use syntax_pos::Span;
 
 use crate::hir::intravisit::{self, NestedVisitorMap, Visitor};
@@ -711,7 +711,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
                         GenericParamKind::Lifetime { .. } => {
                             let (name, reg) = Region::early(&self.tcx.hir(), &mut index, &param);
                             if let hir::ParamName::Plain(param_name) = name {
-                                if param_name.name == keywords::UnderscoreLifetime.name() {
+                                if param_name.name == kw::UnderscoreLifetime {
                                     // Pick the elided lifetime "definition" if one exists
                                     // and use it to make an elision scope.
                                     elision = Some(reg);
@@ -1602,7 +1602,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
                     } {
                         debug!("id = {:?} span = {:?} name = {:?}", id, span, name);
 
-                        if name == keywords::UnderscoreLifetime.ident() {
+                        if name.name == kw::UnderscoreLifetime {
                             continue;
                         }
 
@@ -2525,8 +2525,8 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
         for (i, (lifetime_i, lifetime_i_name)) in lifetimes.iter().enumerate() {
             if let hir::ParamName::Plain(_) = lifetime_i_name {
                 let name = lifetime_i_name.ident().name;
-                if name == keywords::UnderscoreLifetime.name()
-                    || name == keywords::StaticLifetime.name()
+                if name == kw::UnderscoreLifetime
+                    || name == kw::StaticLifetime
                 {
                     let mut err = struct_span_err!(
                         self.tcx.sess,

src/librustc/ty/context.rs

@@ -74,7 +74,7 @@ use syntax::ast;
 use syntax::attr;
 use syntax::source_map::MultiSpan;
 use syntax::feature_gate;
-use syntax::symbol::{Symbol, keywords, InternedString, sym};
+use syntax::symbol::{Symbol, InternedString, kw, sym};
 use syntax_pos::Span;
 
 use crate::hir;
@@ -2735,7 +2735,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 
     #[inline]
     pub fn mk_self_type(self) -> Ty<'tcx> {
-        self.mk_ty_param(0, keywords::SelfUpper.name().as_interned_str())
+        self.mk_ty_param(0, kw::SelfUpper.as_interned_str())
     }
 
     pub fn mk_param_from_def(self, param: &ty::GenericParamDef) -> Kind<'tcx> {

src/librustc/ty/mod.rs

@@ -47,7 +47,7 @@ use std::ops::Range;
 use syntax::ast::{self, Name, Ident, NodeId};
 use syntax::attr;
 use syntax::ext::hygiene::Mark;
-use syntax::symbol::{keywords, sym, Symbol, LocalInternedString, InternedString};
+use syntax::symbol::{kw, sym, Symbol, LocalInternedString, InternedString};
 use syntax_pos::Span;
 
 use smallvec;
@@ -835,7 +835,7 @@ impl ty::EarlyBoundRegion {
     /// Does this early bound region have a name? Early bound regions normally
     /// always have names except when using anonymous lifetimes (`'_`).
     pub fn has_name(&self) -> bool {
-        self.name != keywords::UnderscoreLifetime.name().as_interned_str()
+        self.name != kw::UnderscoreLifetime.as_interned_str()
     }
 }
 

src/librustc/ty/print/pretty.rs

@@ -7,7 +7,7 @@ use crate::middle::region;
 use crate::ty::{self, DefIdTree, ParamConst, Ty, TyCtxt, TypeFoldable};
 use crate::ty::subst::{Kind, Subst, UnpackedKind};
 use crate::mir::interpret::ConstValue;
-use syntax::symbol::{keywords, Symbol};
+use syntax::symbol::{kw, Symbol};
 
 use rustc_target::spec::abi::Abi;
 use syntax::symbol::InternedString;
@@ -982,7 +982,7 @@ impl<F: fmt::Write> Printer<'gcx, 'tcx> for FmtPrinter<'_, 'gcx, 'tcx, F> {
             if self.tcx.sess.rust_2018() {
                 // We add the `crate::` keyword on Rust 2018, only when desired.
                 if SHOULD_PREFIX_WITH_CRATE.with(|flag| flag.get()) {
-                    write!(self, "{}", keywords::Crate.name())?;
+                    write!(self, "{}", kw::Crate)?;
                     self.empty_path = false;
                 }
             }

src/librustc/ty/sty.rs

@@ -22,7 +22,7 @@ use std::marker::PhantomData;
 use std::ops::Range;
 use rustc_target::spec::abi;
 use syntax::ast::{self, Ident};
-use syntax::symbol::{keywords, InternedString};
+use syntax::symbol::{kw, InternedString};
 
 use serialize;
 use self::InferTy::*;
@@ -1121,7 +1121,7 @@ impl<'a, 'gcx, 'tcx> ParamTy {
     }
 
     pub fn for_self() -> ParamTy {
-        ParamTy::new(0, keywords::SelfUpper.name().as_interned_str())
+        ParamTy::new(0, kw::SelfUpper.as_interned_str())
     }
 
     pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
@@ -1136,7 +1136,7 @@ impl<'a, 'gcx, 'tcx> ParamTy {
         // FIXME(#50125): Ignoring `Self` with `index != 0` might lead to weird behavior elsewhere,
         // but this should only be possible when using `-Z continue-parse-after-error` like
         // `compile-fail/issue-36638.rs`.
-        self.name == keywords::SelfUpper.name().as_str() && self.index == 0
+        self.name == kw::SelfUpper.as_str() && self.index == 0
     }
 }
 

src/librustc_codegen_ssa/mir/mod.rs

@@ -10,7 +10,7 @@ use crate::debuginfo::{self, VariableAccess, VariableKind, FunctionDebugContext}
 use crate::traits::*;
 
 use syntax_pos::{DUMMY_SP, NO_EXPANSION, BytePos, Span};
-use syntax::symbol::keywords;
+use syntax::symbol::kw;
 
 use std::iter;
 
@@ -496,7 +496,7 @@ fn arg_local_refs<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>>(
                 };
                 bx.declare_local(
                     &fx.debug_context,
-                    arg_decl.name.unwrap_or(keywords::Invalid.name()),
+                    arg_decl.name.unwrap_or(kw::Invalid),
                     arg_ty, scope,
                     variable_access,
                     VariableKind::ArgumentVariable(arg_index + 1),
@@ -613,7 +613,7 @@ fn arg_local_refs<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>>(
 
                 bx.declare_local(
                     &fx.debug_context,
-                    arg_decl.name.unwrap_or(keywords::Invalid.name()),
+                    arg_decl.name.unwrap_or(kw::Invalid),
                     arg.layout.ty,
                     scope,
                     variable_access,

src/librustc_lint/builtin.rs

@@ -42,7 +42,7 @@ use syntax::edition::Edition;
 use syntax::feature_gate::{AttributeGate, AttributeTemplate, AttributeType};
 use syntax::feature_gate::{Stability, deprecated_attributes};
 use syntax_pos::{BytePos, Span, SyntaxContext};
-use syntax::symbol::{Symbol, keywords, sym};
+use syntax::symbol::{Symbol, kw, sym};
 use syntax::errors::{Applicability, DiagnosticBuilder};
 use syntax::print::pprust::expr_to_string;
 use syntax::visit::FnKind;
@@ -607,7 +607,7 @@ impl EarlyLintPass for AnonymousParameters {
                 for arg in sig.decl.inputs.iter() {
                     match arg.pat.node {
                         ast::PatKind::Ident(_, ident, None) => {
-                            if ident.name == keywords::Invalid.name() {
+                            if ident.name == kw::Invalid {
                                 let ty_snip = cx
                                     .sess
                                     .source_map()