review comments

src/librustc_resolve/lib.rs

@@ -2893,7 +2893,7 @@ fn names_to_string(names: &[Name]) -> String {
         if i > 0 {
             result.push_str("::");
         }
-        if name.is_used_keyword() && name.can_be_raw() {
+        if Ident::with_dummy_span(*name).is_raw_guess() {
             result.push_str("r#");
         }
         result.push_str(&name.as_str());

src/libsyntax_pos/symbol.rs

@@ -1013,15 +1013,7 @@ pub mod sym {
 }
 
 impl Symbol {
-    pub fn is_used_keyword(self) -> bool {
-        self.is_used_keyword_2015() || self.is_used_keyword_2018()
-    }
-
-    pub fn is_used_keyword_2015(self) -> bool {
-        self >= kw::As && self <= kw::While
-    }
-
-    pub fn is_used_keyword_2018(self) -> bool {
+    fn is_used_keyword_2018(self) -> bool {
         self >= kw::Async && self <= kw::Dyn
     }
 
@@ -1065,7 +1057,7 @@ impl Ident {
     /// Returns `true` if the token is a keyword used in the language.
     pub fn is_used_keyword(self) -> bool {
         // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
-        self.name.is_used_keyword_2015() ||
+        self.name >= kw::As && self.name <= kw::While ||
         self.name.is_used_keyword_2018() && self.span.rust_2018()
     }