Reserve 'be' as a keyword

src/libsyntax/parse/common.rs

@@ -85,6 +85,7 @@ impl parser: parser_common {
 
     fn parse_ident() -> ast::ident {
         self.check_strict_keywords();
+        self.check_reserved_keywords();
         match copy self.token {
           token::IDENT(i, _) => { self.bump(); return i; }
           token::INTERPOLATED(token::nt_ident(*)) => { self.bug(
@@ -204,6 +205,26 @@ impl parser: parser_common {
         }
     }
 
+    fn is_reserved_keyword(word: ~str) -> bool {
+        self.reserved_keywords.contains_key_ref(&word)
+    }
+
+    fn check_reserved_keywords() {
+        match self.token {
+          token::IDENT(_, false) => {
+            let w = token_to_str(self.reader, self.token);
+            self.check_reserved_keywords_(w);
+          }
+          _ => ()
+        }
+    }
+
+    fn check_reserved_keywords_(w: ~str) {
+        if self.is_reserved_keyword(w) {
+            self.fatal(~"`" + w + ~"` is a reserved keyword");
+        }
+    }
+
     fn expect_gt() {
         if self.token == token::GT {
             self.bump();

src/libsyntax/parse/parser.rs

@@ -216,6 +216,7 @@ fn parser(sess: parse_sess, cfg: ast::crate_cfg,
         keywords: token::keyword_table(),
         restricted_keywords: token::restricted_keyword_table(),
         strict_keywords: token::strict_keyword_table(),
+        reserved_keywords: token::reserved_keyword_table(),
         obsolete_set: std::map::HashMap(),
     }
 }
@@ -237,6 +238,7 @@ struct parser {
     keywords: HashMap<~str, ()>,
     restricted_keywords: HashMap<~str, ()>,
     strict_keywords: HashMap<~str, ()>,
+    reserved_keywords: HashMap<~str, ()>,
     /// The set of seen errors about obsolete syntax. Used to suppress
     /// extra detail when the same error is seen twice
     obsolete_set: HashMap<ObsoleteSyntax, ()>,

src/libsyntax/parse/token.rs

@@ -379,6 +379,9 @@ fn keyword_table() -> HashMap<~str, ()> {
     for strict_keyword_table().each_key |word| {
         keywords.insert(word, ());
     }
+    for reserved_keyword_table().each_key |word| {
+        keywords.insert(word, ());
+    }
     keywords
 }
 
@@ -447,6 +450,17 @@ fn strict_keyword_table() -> HashMap<~str, ()> {
     words
 }
 
+fn reserved_keyword_table() -> HashMap<~str, ()> {
+    let words = str_hash();
+    let keys = ~[
+        ~"be"
+    ];
+    for keys.each |word| {
+        words.insert(word, ());
+    }
+    words
+}
+
 impl binop : cmp::Eq {
     pure fn eq(&&other: binop) -> bool {
         (self as uint) == (other as uint)

src/test/compile-fail/reserved-be.rs

@@ -0,0 +1,4 @@
+fn main() {
+    let be = 0;
+    //~^ ERROR `be` is a reserved keyword
+}