Implement macro re-export

Fixes #17103.

1 files changed, 41 insertions, 0 deletions

diff --git a/src/libsyntax/ext/tt/reexport.rs b/src/libsyntax/ext/tt/reexport.rs
new file mode 100644
index 00000000000..104f3787253
--- /dev/null
+++ b/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_reexport(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
+}