review comments

src/libsyntax/parse/lexer/mod.rs

@@ -1451,11 +1451,10 @@ impl<'a> StringReader<'a> {
                         self.err_span_(
                             start_with_quote,
                             self.pos,
-                            "lifetimes can't start with a number",
+                            "lifetimes cannot start with a number",
                         );
                     }
 
-
                     return Ok(token::Lifetime(ident));
                 }
 
@@ -1892,7 +1891,7 @@ fn ident_start(c: Option<char>) -> bool {
         None => return false,
     };
 
-    (c.is_alphabetic() || c == '_' || (c > '\x7f' && c.is_xid_start()))
+    (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || c == '_' || (c > '\x7f' && c.is_xid_start())
 }
 
 fn ident_continue(c: Option<char>) -> bool {
@@ -1901,7 +1900,8 @@ fn ident_continue(c: Option<char>) -> bool {
         None => return false,
     };
 
-    (c.is_alphabetic() || c.is_numeric() || c == '_' || (c > '\x7f' && c.is_xid_continue()))
+    (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') || c == '_' ||
+    (c > '\x7f' && c.is_xid_continue())
 }
 
 #[inline]

src/test/ui/parser/numeric-lifetime.rs

@@ -1,6 +1,6 @@
 struct S<'1> { s: &'1 usize }
-//~^ ERROR lifetimes can't start with a number
-//~| ERROR lifetimes can't start with a number
+//~^ ERROR lifetimes cannot start with a number
+//~| ERROR lifetimes cannot start with a number
 fn main() {
     // verify that the parse error doesn't stop type checking
     let x: usize = "";

src/test/ui/parser/numeric-lifetime.stderr

@@ -1,10 +1,10 @@
-error: lifetimes can't start with a number
+error: lifetimes cannot start with a number
   --> $DIR/numeric-lifetime.rs:1:10
    |
 LL | struct S<'1> { s: &'1 usize }
    |          ^^
 
-error: lifetimes can't start with a number
+error: lifetimes cannot start with a number
   --> $DIR/numeric-lifetime.rs:1:20
    |
 LL | struct S<'1> { s: &'1 usize }