rustc: Relax restriction on privacy for fields

This is a necessary change in preparation for switching the defaults as part
of rust-lang#8122.

RFC: 0004-private-fields

Author: alexcrichton

src/librustc/middle/privacy.rs

@@ -1001,10 +1001,6 @@ impl<'a> SanePrivacyVisitor<'a> {
             };
             for f in def.fields.iter() {
                match f.node.kind {
-                    ast::NamedField(_, ast::Public) if public_def => {
-                        tcx.sess.span_err(f.span, "unnecessary `pub` \
-                                                   visibility");
-                    }
                     ast::NamedField(_, ast::Private) if !public_def => {
                         tcx.sess.span_err(f.span, "unnecessary `priv` \
                                                    visibility");

src/test/compile-fail/struct-field-privacy.rs

@@ -25,7 +25,7 @@ mod inner {
     pub struct B {
         a: int,
         priv b: int,
-        pub c: int, //~ ERROR: unnecessary `pub` visibility
+        pub c: int,
     }
 }