librustc: Forbid `pub` or `priv` before trait implementations

3 files changed, 21 insertions, 7 deletions

diff --git a/src/libsyntax/parse/lexer.rs b/src/libsyntax/parse/lexer.rs
index 51cc25e84a3..dc5bdeba92a 100644
--- a/src/libsyntax/parse/lexer.rs
+++ b/src/libsyntax/parse/lexer.rs
@@ -127,7 +127,7 @@ impl reader for StringReader {
     fn dup(@mut self) -> reader { dup_string_reader(self) as reader }
 }
 
-pub impl reader for TtReader {
+impl reader for TtReader {
     fn is_eof(@mut self) -> bool { self.cur_tok == token::EOF }
     fn next_token(@mut self) -> TokenAndSpan { tt_next_token(self) }
     fn fatal(@mut self, m: ~str) -> ! {
diff --git a/src/libsyntax/parse/obsolete.rs b/src/libsyntax/parse/obsolete.rs
index 33d959a7753..b384e7ebdd0 100644
--- a/src/libsyntax/parse/obsolete.rs
+++ b/src/libsyntax/parse/obsolete.rs
@@ -50,9 +50,10 @@ pub enum ObsoleteSyntax {
     ObsoleteTraitBoundSeparator,
     ObsoleteMutOwnedPointer,
     ObsoleteMutVector,
+    ObsoleteTraitImplVisibility,
 }
 
-pub impl to_bytes::IterBytes for ObsoleteSyntax {
+impl to_bytes::IterBytes for ObsoleteSyntax {
     #[inline(always)]
     pure fn iter_bytes(&self, +lsb0: bool, f: to_bytes::Cb) {
         (*self as uint).iter_bytes(lsb0, f);
@@ -140,6 +141,12 @@ pub impl Parser {
                  in a mutable location, like a mutable local variable or an \
                  `@mut` box"
             ),
+            ObsoleteTraitImplVisibility => (
+                "visibility-qualified trait implementation",
+                "`pub` or `priv` is meaningless for trait implementations, \
+                 because the `impl...for...` form defines overloads for \
+                 methods that already exist; remove the `pub` or `priv`"
+            ),
         };
 
         self.report(sp, kind, kind_str, desc);
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index b4bd28cbfe2..59ad35b38e4 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -76,7 +76,7 @@ use parse::obsolete::{ObsoleteStructCtor, ObsoleteWith};
 use parse::obsolete::{ObsoleteSyntax, ObsoleteLowerCaseKindBounds};
 use parse::obsolete::{ObsoleteUnsafeBlock, ObsoleteImplSyntax};
 use parse::obsolete::{ObsoleteTraitBoundSeparator, ObsoleteMutOwnedPointer};
-use parse::obsolete::{ObsoleteMutVector};
+use parse::obsolete::{ObsoleteMutVector, ObsoleteTraitImplVisibility};
 use parse::prec::{as_prec, token_to_binop};
 use parse::token::{can_begin_expr, is_ident, is_ident_or_path};
 use parse::token::{is_plain_ident, INTERPOLATED, special_idents};
@@ -2942,9 +2942,9 @@ pub impl Parser {
     }
 
     // Parses two variants (with the region/type params always optional):
-    //    impl<T> ~[T] : to_str { ... }
-    //    impl<T> to_str for ~[T] { ... }
-    fn parse_item_impl() -> item_info {
+    //    impl<T> Foo { ... }
+    //    impl<T> ToStr for ~[T] { ... }
+    fn parse_item_impl(visibility: ast::visibility) -> item_info {
         fn wrap_path(p: Parser, pt: @path) -> @Ty {
             @Ty {
                 id: p.get_id(),
@@ -2993,6 +2993,12 @@ pub impl Parser {
             None
         };
 
+        // Do not allow visibility to be specified in `impl...for...`. It is
+        // meaningless.
+        if opt_trait.is_some() && visibility != ast::inherited {
+            self.obsolete(*self.span, ObsoleteTraitImplVisibility);
+        }
+
         let mut meths = ~[];
         if !self.eat(token::SEMI) {
             self.expect(token::LBRACE);
@@ -3860,7 +3866,8 @@ pub impl Parser {
                                           maybe_append(attrs, extra_attrs)));
         } else if items_allowed && self.eat_keyword(~"impl") {
             // IMPL ITEM
-            let (ident, item_, extra_attrs) = self.parse_item_impl();
+            let (ident, item_, extra_attrs) =
+                self.parse_item_impl(visibility);
             return iovi_item(self.mk_item(lo, self.last_span.hi, ident, item_,
                                           visibility,
                                           maybe_append(attrs, extra_attrs)));