Move is_gensymed from Symbol to Ident.

Note that the `is_gensymed` call on `primitive_types` is unnecessary
because that table only contains the name of primitive types (e.g.
`i32`) and never contains gensyms.

Author: nnethercote

Diff for: src/librustc_resolve/lib.rs

@@ -4225,7 +4225,7 @@ impl<'a> Resolver<'a> {
         let add_module_candidates = |module: Module<'_>, names: &mut Vec<TypoSuggestion>| {
             for (&(ident, _), resolution) in module.resolutions.borrow().iter() {
                 if let Some(binding) = resolution.borrow().binding {
-                    if !ident.name.is_gensymed() && filter_fn(binding.res()) {
+                    if !ident.is_gensymed() && filter_fn(binding.res()) {
                         names.push(TypoSuggestion {
                             candidate: ident.name,
                             article: binding.res().article(),
@@ -4243,7 +4243,7 @@ impl<'a> Resolver<'a> {
             for rib in self.ribs[ns].iter().rev() {
                 // Locals and type parameters
                 for (ident, &res) in &rib.bindings {
-                    if !ident.name.is_gensymed() && filter_fn(res) {
+                    if !ident.is_gensymed() && filter_fn(res) {
                         names.push(TypoSuggestion {
                             candidate: ident.name,
                             article: res.article(),
@@ -4273,7 +4273,7 @@ impl<'a> Resolver<'a> {
                                             },
                                         );
 
-                                        if !ident.name.is_gensymed() && filter_fn(crate_mod) {
+                                        if !ident.is_gensymed() && filter_fn(crate_mod) {
                                             Some(TypoSuggestion {
                                                 candidate: ident.name,
                                                 article: "a",
@@ -4298,7 +4298,6 @@ impl<'a> Resolver<'a> {
                 names.extend(
                     self.primitive_type_table.primitive_types
                         .iter()
-                        .filter(|(name, _)| !name.is_gensymed())
                         .map(|(name, _)| {
                             TypoSuggestion {
                                 candidate: *name,

Diff for: src/librustc_resolve/resolve_imports.rs

@@ -1395,7 +1395,7 @@ impl<'a, 'b:'a> ImportResolver<'a, 'b> {
             // so they can cause name conflict errors downstream.
             let is_good_import = binding.is_import() && !binding.is_ambiguity() &&
                                  // Note that as_str() de-gensyms the Symbol
-                                 !(ident.name.is_gensymed() && ident.name.as_str() != "_");
+                                 !(ident.is_gensymed() && ident.name.as_str() != "_");
             if is_good_import || binding.is_macro_def() {
                 let res = binding.res();
                 if res != Res::Err {

Diff for: src/libsyntax/ast.rs

@@ -72,11 +72,7 @@ pub struct Path {
 impl PartialEq<Symbol> for Path {
     fn eq(&self, symbol: &Symbol) -> bool {
         self.segments.len() == 1 && {
-            let name = self.segments[0].ident.name;
-            // Make sure these symbols are pure strings
-            debug_assert!(!symbol.is_gensymed());
-            debug_assert!(!name.is_gensymed());
-            name == *symbol
+            self.segments[0].ident.name == *symbol
         }
     }
 }

Diff for: src/libsyntax_pos/symbol.rs

@@ -684,6 +684,11 @@ impl Ident {
         if self.name == keywords::Underscore.name() { self.gensym() } else { self }
     }
 
+    // WARNING: this function is deprecated and will be removed in the future.
+    pub fn is_gensymed(self) -> bool {
+        with_interner(|interner| interner.is_gensymed(self.name))
+    }
+
     pub fn as_str(self) -> LocalInternedString {
         self.name.as_str()
     }
@@ -786,11 +791,6 @@ impl Symbol {
         with_interner(|interner| interner.gensymed(self))
     }
 
-    // WARNING: this function is deprecated and will be removed in the future.
-    pub fn is_gensymed(self) -> bool {
-        with_interner(|interner| interner.is_gensymed(self))
-    }
-
     pub fn as_str(self) -> LocalInternedString {
         with_interner(|interner| unsafe {
             LocalInternedString {