Implement macro re-export

Fixes rust-lang#17103.

src/librustc/driver/driver.rs

@@ -273,6 +273,8 @@ pub fn phase_2_configure_and_expand(sess: &Session,
             let cfg = syntax::ext::expand::ExpansionConfig {
                 deriving_hash_type_parameter: sess.features.default_type_params.get(),
                 crate_name: crate_name.to_string(),
+                reexported_macros: syntax::ext::tt::reexport::gather(sess.diagnostic(),
+                                                                     &krate),
             };
             let ret = syntax::ext::expand::expand_crate(&sess.parse_sess,
                                               cfg,

src/librustc/front/test.rs

@@ -232,6 +232,7 @@ fn generate_test_harness(sess: &Session,
                              ExpansionConfig {
                                  deriving_hash_type_parameter: false,
                                  crate_name: "test".to_string(),
+                                 reexported_macros: vec!(),
                              }),
         path: Vec::new(),
         testfns: Vec::new(),

src/libsyntax/ext/expand.rs

@@ -455,7 +455,12 @@ pub fn expand_item_mac(it: P<ast::Item>,
                                                          imported_from, tts);
 
                     fld.cx.syntax_env.insert(intern(name.as_slice()), ext);
-                    if attr::contains_name(it.attrs.as_slice(), "macro_export") {
+
+                    if match imported_from {
+                        None => attr::contains_name(it.attrs.as_slice(), "macro_export"),
+                        Some(_) => fld.cx.ecfg.reexported_macros.iter()
+                                       .any(|e| e.as_slice() == name.as_slice()),
+                    } {
                         fld.cx.exported_macros.push(it);
                     }
 
@@ -968,6 +973,7 @@ fn new_span(cx: &ExtCtxt, sp: Span) -> Span {
 pub struct ExpansionConfig {
     pub deriving_hash_type_parameter: bool,
     pub crate_name: String,
+    pub reexported_macros: Vec<String>,
 }
 
 pub struct ExportedMacros {
@@ -1181,6 +1187,7 @@ mod test {
         ExpansionConfig {
             deriving_hash_type_parameter: false,
             crate_name: "test".to_string(),
+            reexported_macros: vec!(),
         }
     }
 

src/libsyntax/ext/tt/reexport.rs

@@ -0,0 +1,41 @@
+// Copyright 2014 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.
+
+//! Defines the crate attribute syntax for macro re-export.
+
+use ast;
+use attr::AttrMetaMethods;
+use diagnostic::SpanHandler;
+
+/// Return a vector of the names of all macros re-exported from the crate.
+pub fn gather(diag: &SpanHandler, krate: &ast::Crate) -> Vec<String> {
+    let usage = "malformed macro_reexport attribute, expected \
+                 #![macro_export(ident, ident, ...)]";
+
+    let mut reexported: Vec<String> = vec!();
+    for attr in krate.attrs.iter() {
+        if !attr.check_name("macro_reexport") {
+            continue;
+        }
+
+        match attr.meta_item_list() {
+            None => diag.span_err(attr.span, usage),
+            Some(list) => for mi in list.iter() {
+                match mi.node {
+                    ast::MetaWord(ref word)
+                        => reexported.push(word.to_string()),
+                    _ => diag.span_err(mi.span, usage),
+                }
+            }
+        }
+    }
+
+    reexported
+}

src/libsyntax/lib.rs

@@ -95,5 +95,6 @@ pub mod ext {
         pub mod transcribe;
         pub mod macro_parser;
         pub mod macro_rules;
+        pub mod reexport;
     }
 }

src/test/auxiliary/macro_reexport_1.rs

@@ -0,0 +1,15 @@
+// Copyright 2014 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.
+
+#![crate_type = "dylib"]
+#![feature(macro_rules)]
+
+#[macro_export]
+macro_rules! reexported ( () => ( 3u ) )

src/test/auxiliary/macro_reexport_2.rs

@@ -0,0 +1,17 @@
+// Copyright 2014 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.
+
+#![crate_type = "dylib"]
+#![feature(phase)]
+
+#![macro_reexport(reexported)]
+
+#[phase(plugin)]
+extern crate macro_reexport_1;

src/test/compile-fail/macro-reexport-malformed-1.rs

@@ -0,0 +1,13 @@
+// Copyright 2014 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_reexport]  //~ ERROR malformed macro_reexport attribute
+
+fn main() { }

src/test/compile-fail/macro-reexport-malformed-2.rs

@@ -0,0 +1,13 @@
+// Copyright 2014 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_reexport="foo"]  //~ ERROR malformed macro_reexport attribute
+
+fn main() { }

src/test/compile-fail/macro-reexport-malformed-3.rs

@@ -0,0 +1,13 @@
+// Copyright 2014 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_reexport(foo="bar")]  //~ ERROR malformed macro_reexport attribute
+
+fn main() { }

src/test/run-pass/macro-reexport.rs

@@ -0,0 +1,22 @@
+// Copyright 2014 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.
+
+// aux-build:macro_reexport_1.rs
+// aux-build:macro_reexport_2.rs
+// ignore-stage1
+
+#![feature(phase)]
+
+#[phase(plugin)]
+extern crate macro_reexport_2;
+
+fn main() {
+    assert_eq!(reexported!(), 3u);
+}