Custom help message for people trying to make macro public

src/libsyntax/parse/parser.rs

@@ -67,7 +67,7 @@ use parse::classify;
 use parse::common::{SeqSep, seq_sep_none, seq_sep_trailing_allowed};
 use parse::lexer::{Reader, TokenAndSpan};
 use parse::obsolete::{ParserObsoleteMethods, ObsoleteSyntax};
-use parse::token::{self, MatchNt, SubstNt, SpecialVarNt, InternedString};
+use parse::token::{self, intern, MatchNt, SubstNt, SpecialVarNt, InternedString};
 use parse::token::{keywords, special_idents, SpecialMacroVar};
 use parse::{new_sub_parser_from_file, ParseSess};
 use util::parser::{AssocOp, Fixity};
@@ -4612,10 +4612,22 @@ impl<'a> Parser<'a> {
     fn complain_if_pub_macro(&mut self, visa: Visibility, span: Span) {
         match visa {
             Public => {
-                self.diagnostic().struct_span_err(span, "can't qualify macro invocation with `pub`")
-                                 .fileline_help(span, "try adjusting the macro to put `pub` inside \
-                                                       the invocation")
-                                 .emit();
+                let is_macro_rules: bool = match self.token {
+                    token::Ident(sid, _) => sid.name == intern("macro_rules"),
+                    _ => false,
+                };
+                if is_macro_rules {
+                    self.diagnostic().struct_span_err(span, "can't qualify macro_rules \
+                                                             invocation with `pub`")
+                                     .fileline_help(span, "did you mean #[macro_export]?")
+                                     .emit();
+                } else {
+                    self.diagnostic().struct_span_err(span, "can't qualify macro \
+                                                             invocation with `pub`")
+                                     .fileline_help(span, "try adjusting the macro to put `pub` \
+                                                           inside the invocation")
+                                     .emit();
+                }
             }
             Inherited => (),
         }

src/test/parse-fail/pub-macro-rules.rs

@@ -0,0 +1,27 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#[macro_use] mod bleh {
+    pub macro_rules! foo { //~ ERROR can't qualify macro_rules invocation with `pub`
+    //~^ HELP did you mean #[macro_export]?
+        ($n:ident) => (
+            fn $n () -> i32 {
+                1
+            }
+        )
+    }
+
+}
+
+foo!(meh);
+
+fn main() {
+    println!("{}", meh());
+}