Auto merge of #61035 - nnethercote:avoid-more-symbol-interning, r=pet…

…rochenkov

Avoid more symbol interning

r? @petrochenkov

Cargo.lock

@@ -3009,6 +3009,7 @@ dependencies = [
  "rustc_cratesio_shim 0.0.0",
  "rustc_data_structures 0.0.0",
  "serialize 0.0.0",
+ "syntax_pos 0.0.0",
 ]
 
 [[package]]

src/librustc/hir/lowering.rs

@@ -1145,9 +1145,7 @@ impl<'a> LoweringContext<'a> {
         let unstable_span = self.sess.source_map().mark_span_with_reason(
             CompilerDesugaringKind::Async,
             span,
-            Some(vec![
-                Symbol::intern("gen_future"),
-            ].into()),
+            Some(vec![sym::gen_future].into()),
         );
         let gen_future = self.expr_std_path(
             unstable_span, &[sym::future, sym::from_generator], None, ThinVec::new());
@@ -2958,7 +2956,7 @@ impl<'a> LoweringContext<'a> {
             ident: match f.ident {
                 Some(ident) => ident,
                 // FIXME(jseyfried): positional field hygiene
-                None => Ident::new(Symbol::intern(&index.to_string()), f.span),
+                None => Ident::new(sym::integer(index), f.span),
             },
             vis: self.lower_visibility(&f.vis, None),
             ty: self.lower_ty(&f.ty, ImplTraitContext::disallowed()),
@@ -4177,9 +4175,7 @@ impl<'a> LoweringContext<'a> {
                     let unstable_span = this.sess.source_map().mark_span_with_reason(
                         CompilerDesugaringKind::TryBlock,
                         body.span,
-                        Some(vec![
-                            Symbol::intern("try_trait"),
-                        ].into()),
+                        Some(vec![sym::try_trait].into()),
                     );
                     let mut block = this.lower_block(body, true).into_inner();
                     let tail = block.expr.take().map_or_else(

src/librustc/hir/map/def_collector.rs

@@ -5,8 +5,7 @@ use crate::session::CrateDisambiguator;
 use syntax::ast::*;
 use syntax::ext::hygiene::Mark;
 use syntax::visit;
-use syntax::symbol::kw;
-use syntax::symbol::Symbol;
+use syntax::symbol::{kw, sym};
 use syntax::parse::token::{self, Token};
 use syntax_pos::Span;
 
@@ -221,7 +220,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
                           _: &'a Generics, _: NodeId, _: Span) {
         for (index, field) in data.fields().iter().enumerate() {
             let name = field.ident.map(|ident| ident.name)
-                .unwrap_or_else(|| Symbol::intern(&index.to_string()));
+                .unwrap_or_else(|| sym::integer(index));
             let def = self.create_def(field.id,
                                       DefPathData::ValueNs(name.as_interned_str()),
                                       field.span);

src/librustc/middle/lang_items.rs

@@ -210,8 +210,8 @@ impl<'a, 'tcx> LanguageItemCollector<'a, 'tcx> {
 pub fn extract(attrs: &[ast::Attribute]) -> Option<(Symbol, Span)> {
     attrs.iter().find_map(|attr| Some(match attr {
         _ if attr.check_name(sym::lang) => (attr.value_str()?, attr.span),
-        _ if attr.check_name(sym::panic_handler) => (Symbol::intern("panic_impl"), attr.span),
-        _ if attr.check_name(sym::alloc_error_handler) => (Symbol::intern("oom"), attr.span),
+        _ if attr.check_name(sym::panic_handler) => (sym::panic_impl, attr.span),
+        _ if attr.check_name(sym::alloc_error_handler) => (sym::oom, attr.span),
         _ => return None,
     }))
 }

src/librustc/middle/mem_categorization.rs

@@ -1316,7 +1316,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
 
                 for (i, subpat) in subpats.iter().enumerate_and_adjust(expected_len, ddpos) {
                     let subpat_ty = self.pat_ty_adjusted(&subpat)?; // see (*2)
-                    let interior = InteriorField(FieldIndex(i, Name::intern(&i.to_string())));
+                    let interior = InteriorField(FieldIndex(i, sym::integer(i)));
                     let subcmt = Rc::new(
                         self.cat_imm_interior(pat, cmt.clone(), subpat_ty, interior));
                     self.cat_pattern_(subcmt, &subpat, op)?;
@@ -1363,7 +1363,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
                 };
                 for (i, subpat) in subpats.iter().enumerate_and_adjust(expected_len, ddpos) {
                     let subpat_ty = self.pat_ty_adjusted(&subpat)?; // see (*2)
-                    let interior = InteriorField(FieldIndex(i, Name::intern(&i.to_string())));
+                    let interior = InteriorField(FieldIndex(i, sym::integer(i)));
                     let subcmt = Rc::new(
                         self.cat_imm_interior(pat, cmt.clone(), subpat_ty, interior));
                     self.cat_pattern_(subcmt, &subpat, op)?;

src/librustc/middle/stability.rs

@@ -437,7 +437,7 @@ impl<'a, 'tcx> Index<'tcx> {
                         reason: Some(Symbol::intern(reason)),
                         issue: 27812,
                     },
-                    feature: Symbol::intern("rustc_private"),
+                    feature: sym::rustc_private,
                     rustc_depr: None,
                     const_stability: None,
                     promotable: false,
@@ -880,7 +880,7 @@ pub fn check_unused_or_stable_features<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
     // FIXME: only remove `libc` when `stdbuild` is active.
     // FIXME: remove special casing for `test`.
     remaining_lib_features.remove(&Symbol::intern("libc"));
-    remaining_lib_features.remove(&Symbol::intern("test"));
+    remaining_lib_features.remove(&sym::test);
 
     let check_features =
         |remaining_lib_features: &mut FxHashMap<_, _>, defined_features: &[_]| {

src/librustc/session/config.rs

@@ -19,7 +19,7 @@ use syntax::source_map::{FileName, FilePathMapping};
 use syntax::edition::{Edition, EDITION_NAME_LIST, DEFAULT_EDITION};
 use syntax::parse::token;
 use syntax::parse;
-use syntax::symbol::Symbol;
+use syntax::symbol::{sym, Symbol};
 use syntax::feature_gate::UnstableFeatures;
 use errors::emitter::HumanReadableErrorType;
 
@@ -1503,31 +1503,31 @@ pub fn default_configuration(sess: &Session) -> ast::CrateConfig {
         Some(Symbol::intern(vendor)),
     ));
     if sess.target.target.options.has_elf_tls {
-        ret.insert((Symbol::intern("target_thread_local"), None));
+        ret.insert((sym::target_thread_local, None));
     }
     for &i in &[8, 16, 32, 64, 128] {
         if i >= min_atomic_width && i <= max_atomic_width {
             let s = i.to_string();
             ret.insert((
-                Symbol::intern("target_has_atomic"),
+                sym::target_has_atomic,
                 Some(Symbol::intern(&s)),
             ));
             if &s == wordsz {
                 ret.insert((
-                    Symbol::intern("target_has_atomic"),
+                    sym::target_has_atomic,
                     Some(Symbol::intern("ptr")),
                 ));
             }
         }
     }
     if atomic_cas {
-        ret.insert((Symbol::intern("target_has_atomic"), Some(Symbol::intern("cas"))));
+        ret.insert((sym::target_has_atomic, Some(Symbol::intern("cas"))));
     }
     if sess.opts.debug_assertions {
         ret.insert((Symbol::intern("debug_assertions"), None));
     }
     if sess.opts.crate_types.contains(&CrateType::ProcMacro) {
-        ret.insert((Symbol::intern("proc_macro"), None));
+        ret.insert((sym::proc_macro, None));
     }
     ret
 }
@@ -1547,7 +1547,7 @@ pub fn build_configuration(sess: &Session, mut user_cfg: ast::CrateConfig) -> as
     let default_cfg = default_configuration(sess);
     // If the user wants a test runner, then add the test cfg
     if sess.opts.test {
-        user_cfg.insert((Symbol::intern("test"), None));
+        user_cfg.insert((sym::test, None));
     }
     user_cfg.extend(default_cfg.iter().cloned());
     user_cfg
@@ -2702,7 +2702,7 @@ mod tests {
     use std::path::PathBuf;
     use super::{Externs, OutputType, OutputTypes};
     use rustc_target::spec::{MergeFunctions, PanicStrategy, RelroLevel};
-    use syntax::symbol::Symbol;
+    use syntax::symbol::sym;
     use syntax::edition::{Edition, DEFAULT_EDITION};
     use syntax;
     use super::Options;
@@ -2744,15 +2744,14 @@ mod tests {
             let (sessopts, cfg) = build_session_options_and_crate_config(matches);
             let sess = build_session(sessopts, None, registry);
             let cfg = build_configuration(&sess, to_crate_config(cfg));
-            assert!(cfg.contains(&(Symbol::intern("test"), None)));
+            assert!(cfg.contains(&(sym::test, None)));
         });
     }
 
     // When the user supplies --test and --cfg test, don't implicitly add
     // another --cfg test
     #[test]
     fn test_switch_implies_cfg_test_unless_cfg_test() {
-        use syntax::symbol::sym;
         syntax::with_default_globals(|| {
             let matches = &match optgroups().parse(&["--test".to_string(),
                                                      "--cfg=test".to_string()]) {

src/librustc_allocator/expand.rs

@@ -91,9 +91,7 @@ impl MutVisitor for ExpandAllocatorDirectives<'_> {
             call_site: item.span, // use the call site of the static
             def_site: None,
             format: MacroAttribute(Symbol::intern(name)),
-            allow_internal_unstable: Some(vec![
-                Symbol::intern("rustc_attrs"),
-            ].into()),
+            allow_internal_unstable: Some(vec![sym::rustc_attrs].into()),
             allow_internal_unsafe: false,
             local_inner_macros: false,
             edition: self.sess.edition,
@@ -223,7 +221,7 @@ impl AllocFnFactory<'_> {
     }
 
     fn attrs(&self) -> Vec<Attribute> {
-        let special = Symbol::intern("rustc_std_internal_symbol");
+        let special = sym::rustc_std_internal_symbol;
         let special = self.cx.meta_word(self.span, special);
         vec![self.cx.attribute(self.span, special)]
     }

src/librustc_interface/util.rs

@@ -68,7 +68,7 @@ pub fn add_configuration(
     sess: &Session,
     codegen_backend: &dyn CodegenBackend,
 ) {
-    let tf = Symbol::intern("target_feature");
+    let tf = sym::target_feature;
 
     cfg.extend(
         codegen_backend

src/librustc_lint/builtin.rs

@@ -1439,8 +1439,8 @@ impl KeywordIdents {
     {
         let next_edition = match cx.sess.edition() {
             Edition::Edition2015 => {
-                match &ident.as_str()[..] {
-                    "async" | "await" | "try" => Edition::Edition2018,
+                match ident.name {
+                    kw::Async | kw::Await | kw::Try => Edition::Edition2018,
 
                     // rust-lang/rust#56327: Conservatively do not
                     // attempt to report occurrences of `dyn` within
@@ -1454,7 +1454,7 @@ impl KeywordIdents {
                     // its precise role in the parsed AST and thus are
                     // assured this is truly an attempt to use it as
                     // an identifier.
-                    "dyn" if !under_macro => Edition::Edition2018,
+                    kw::Dyn if !under_macro => Edition::Edition2018,
 
                     _ => return,
                 }

src/librustc_macros/src/symbols.rs

@@ -96,6 +96,7 @@ pub fn symbols(input: TokenStream) -> TokenStream {
 
     let mut keyword_stream = quote! {};
     let mut symbols_stream = quote! {};
+    let mut digits_stream = quote! {};
     let mut prefill_stream = quote! {};
     let mut counter = 0u32;
     let mut keys = HashSet::<String>::new();
@@ -106,6 +107,7 @@ pub fn symbols(input: TokenStream) -> TokenStream {
         }
     };
 
+    // Generate the listed keywords.
     for keyword in &input.keywords.0 {
         let name = &keyword.name;
         let value = &keyword.value;
@@ -119,6 +121,7 @@ pub fn symbols(input: TokenStream) -> TokenStream {
         counter += 1;
     }
 
+    // Generate the listed symbols.
     for symbol in &input.symbols.0 {
         let name = &symbol.name;
         let value = match &symbol.value {
@@ -135,6 +138,19 @@ pub fn symbols(input: TokenStream) -> TokenStream {
         counter += 1;
     }
 
+    // Generate symbols for the strings "0", "1", ..., "9".
+    for n in 0..10 {
+        let n = n.to_string();
+        check_dup(&n);
+        prefill_stream.extend(quote! {
+            #n,
+        });
+        digits_stream.extend(quote! {
+            Symbol::new(#counter),
+        });
+        counter += 1;
+    }
+
     let tt = TokenStream::from(quote! {
         macro_rules! keywords {
             () => {
@@ -145,6 +161,10 @@ pub fn symbols(input: TokenStream) -> TokenStream {
         macro_rules! symbols {
             () => {
                 #symbols_stream
+
+                pub const digits_array: &[Symbol; 10] = &[
+                    #digits_stream
+                ];
             }
         }
 

src/librustc_metadata/cstore_impl.rs

@@ -431,9 +431,7 @@ impl cstore::CStore {
             let client = proc_macro::bridge::client::Client::expand1(proc_macro::quote);
             let ext = SyntaxExtension::ProcMacro {
                 expander: Box::new(BangProcMacro { client }),
-                allow_internal_unstable: Some(vec![
-                    Symbol::intern("proc_macro_def_site"),
-                ].into()),
+                allow_internal_unstable: Some(vec![sym::proc_macro_def_site].into()),
                 edition: data.root.edition,
             };
             return LoadedMacro::ProcMacro(Lrc::new(ext));

src/librustc_mir/interpret/validity.rs

@@ -2,7 +2,7 @@ use std::fmt::Write;
 use std::hash::Hash;
 use std::ops::RangeInclusive;
 
-use syntax_pos::symbol::Symbol;
+use syntax_pos::symbol::{sym, Symbol};
 use rustc::hir;
 use rustc::ty::layout::{self, Size, Align, TyLayout, LayoutOf, VariantIdx};
 use rustc::ty;
@@ -188,7 +188,7 @@ impl<'rt, 'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> ValidityVisitor<'rt, 'a, '
 
                 PathElem::ClosureVar(name.unwrap_or_else(|| {
                     // Fall back to showing the field index.
-                    Symbol::intern(&field.to_string())
+                    sym::integer(field)
                 }))
             }
 

src/librustc_target/Cargo.toml

@@ -15,3 +15,4 @@ log = "0.4"
 rustc_cratesio_shim = { path = "../librustc_cratesio_shim" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 serialize = { path = "../libserialize" }
+syntax_pos = { path = "../libsyntax_pos" }

src/librustc_target/abi/mod.rs

@@ -7,6 +7,7 @@ use std::fmt;
 use std::ops::{Add, Deref, Sub, Mul, AddAssign, Range, RangeInclusive};
 
 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
+use syntax_pos::symbol::{sym, Symbol};
 
 pub mod call;
 
@@ -552,6 +553,13 @@ impl FloatTy {
         }
     }
 
+    pub fn to_symbol(self) -> Symbol {
+        match self {
+            FloatTy::F32 => sym::f32,
+            FloatTy::F64 => sym::f64,
+        }
+    }
+
     pub fn bit_width(self) -> usize {
         match self {
             FloatTy::F32 => 32,

src/librustc_typeck/check/mod.rs

@@ -2697,16 +2697,12 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
 
     fn resolve_place_op(&self, op: PlaceOp, is_mut: bool) -> (Option<DefId>, ast::Ident) {
         let (tr, name) = match (op, is_mut) {
-            (PlaceOp::Deref, false) =>
-                (self.tcx.lang_items().deref_trait(), "deref"),
-            (PlaceOp::Deref, true) =>
-                (self.tcx.lang_items().deref_mut_trait(), "deref_mut"),
-            (PlaceOp::Index, false) =>
-                (self.tcx.lang_items().index_trait(), "index"),
-            (PlaceOp::Index, true) =>
-                (self.tcx.lang_items().index_mut_trait(), "index_mut"),
+            (PlaceOp::Deref, false) => (self.tcx.lang_items().deref_trait(), sym::deref),
+            (PlaceOp::Deref, true) => (self.tcx.lang_items().deref_mut_trait(), sym::deref_mut),
+            (PlaceOp::Index, false) => (self.tcx.lang_items().index_trait(), sym::index),
+            (PlaceOp::Index, true) => (self.tcx.lang_items().index_mut_trait(), sym::index_mut),
         };
-        (tr, ast::Ident::from_str(name))
+        (tr, ast::Ident::with_empty_ctxt(name))
     }
 
     fn try_overloaded_place_op(&self,
@@ -4948,7 +4944,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                 // This is less than ideal, it will not suggest a return type span on any
                 // method called `main`, regardless of whether it is actually the entry point,
                 // but it will still present it as the reason for the expected type.
-                Some((decl, ident, ident.name != Symbol::intern("main")))
+                Some((decl, ident, ident.name != sym::main))
             }),
             Node::TraitItem(&hir::TraitItem {
                 ident, node: hir::TraitItemKind::Method(hir::MethodSig {