Check for conflicts between macros 1.0 exports (`#[macro_export]`, `#[macro_reexport]`)

and macros 2.0 exports (`pub use` macro re-exports and `pub macro` (once implemented)
at the crate root.

3 files changed, 18 insertions, 7 deletions

diff --git a/src/librustc_resolve/build_reduced_graph.rs b/src/librustc_resolve/build_reduced_graph.rs
index be905a9d0f9..c33d5b9b6e1 100644
--- a/src/librustc_resolve/build_reduced_graph.rs
+++ b/src/librustc_resolve/build_reduced_graph.rs
@@ -605,7 +605,7 @@ impl<'a> Resolver<'a> {
             let ident = Ident::with_empty_ctxt(name);
             let result = self.resolve_ident_in_module(module, ident, MacroNS, false, None);
             if let Ok(binding) = result {
-                self.macro_exports.push(Export { name: name, def: binding.def() });
+                self.macro_exports.push(Export { name: name, def: binding.def(), span: span });
             } else {
                 span_err!(self.session, span, E0470, "reexported macro not found");
             }
diff --git a/src/librustc_resolve/macros.rs b/src/librustc_resolve/macros.rs
index df3be8fa0f8..f72c2eadb04 100644
--- a/src/librustc_resolve/macros.rs
+++ b/src/librustc_resolve/macros.rs
@@ -653,7 +653,7 @@ impl<'a> Resolver<'a> {
 
         if attr::contains_name(&item.attrs, "macro_export") {
             let def = Def::Macro(def_id, MacroKind::Bang);
-            self.macro_exports.push(Export { name: ident.name, def: def });
+            self.macro_exports.push(Export { name: ident.name, def: def, span: item.span });
         }
     }
 
diff --git a/src/librustc_resolve/resolve_imports.rs b/src/librustc_resolve/resolve_imports.rs
index dbc8bca548b..2f4ac12cd73 100644
--- a/src/librustc_resolve/resolve_imports.rs
+++ b/src/librustc_resolve/resolve_imports.rs
@@ -21,7 +21,7 @@ use rustc::ty;
 use rustc::lint::builtin::PRIVATE_IN_PUBLIC;
 use rustc::hir::def_id::DefId;
 use rustc::hir::def::*;
-use rustc::util::nodemap::FxHashSet;
+use rustc::util::nodemap::FxHashMap;
 
 use syntax::ast::{Ident, NodeId};
 use syntax::ext::base::Determinacy::{self, Determined, Undetermined};
@@ -763,10 +763,11 @@ impl<'a, 'b:'a> ImportResolver<'a, 'b> {
         *module.globs.borrow_mut() = Vec::new();
 
         let mut reexports = Vec::new();
+        let mut exported_macro_names = FxHashMap();
         if module as *const _ == self.graph_root as *const _ {
-            let mut exported_macro_names = FxHashSet();
-            for export in mem::replace(&mut self.macro_exports, Vec::new()).into_iter().rev() {
-                if exported_macro_names.insert(export.name) {
+            let macro_exports = mem::replace(&mut self.macro_exports, Vec::new());
+            for export in macro_exports.into_iter().rev() {
+                if exported_macro_names.insert(export.name, export.span).is_none() {
                     reexports.push(export);
                 }
             }
@@ -786,7 +787,17 @@ impl<'a, 'b:'a> ImportResolver<'a, 'b> {
                     if !def.def_id().is_local() {
                         self.session.cstore.export_macros(def.def_id().krate);
                     }
-                    reexports.push(Export { name: ident.name, def: def });
+                    if let Def::Macro(..) = def {
+                        if let Some(&span) = exported_macro_names.get(&ident.name) {
+                            let msg =
+                                format!("a macro named `{}` has already been exported", ident);
+                            self.session.struct_span_err(span, &msg)
+                                .span_label(span, &format!("`{}` already exported", ident))
+                                .span_note(binding.span, "previous macro export here")
+                                .emit();
+                        }
+                    }
+                    reexports.push(Export { name: ident.name, def: def, span: binding.span });
                 }
             }