From 51499b6e1fd892b68eeb28eaec9031f01a6a9409 Mon Sep 17 00:00:00 2001
From: Jeffrey Seyfried <jeffrey.seyfried@gmail.com>
Date: Thu, 2 Jun 2016 01:14:33 +0000
Subject: Load macros from `extern crate`s during expansion.

---
 src/libsyntax/ext/expand.rs | 41 ++++++++++++++++++++++-------------------
 1 file changed, 22 insertions(+), 19 deletions(-)

(limited to 'src/libsyntax/ext/expand.rs')

diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 7fee27c5dd4..c581a149f43 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -750,6 +750,15 @@ fn expand_annotatable(a: Annotatable,
                 }
                 result.into_iter().map(|i| Annotatable::Item(i)).collect()
             },
+            ast::ItemKind::ExternCrate(_) => {
+                // We need to error on `#[macro_use] extern crate` when it isn't at the
+                // crate root, because `$crate` won't work properly.
+                let allows_macros = fld.cx.syntax_env.is_crate_root();
+                for def in fld.cx.loader.load_crate(&it, allows_macros) {
+                    fld.cx.insert_macro(def);
+                }
+                SmallVector::one(Annotatable::Item(it))
+            },
             _ => noop_fold_item(it, fld).into_iter().map(|i| Annotatable::Item(i)).collect(),
         },
 
@@ -1137,8 +1146,6 @@ impl<'feat> ExpansionConfig<'feat> {
 }
 
 pub fn expand_crate(mut cx: ExtCtxt,
-                    // these are the macros being imported to this crate:
-                    imported_macros: Vec<ast::MacroDef>,
                     user_exts: Vec<NamedSyntaxExtension>,
                     c: Crate) -> (Crate, HashSet<Name>) {
     if std_inject::no_core(&c) {
@@ -1151,10 +1158,6 @@ pub fn expand_crate(mut cx: ExtCtxt,
     let ret = {
         let mut expander = MacroExpander::new(&mut cx);
 
-        for def in imported_macros {
-            expander.cx.insert_macro(def);
-        }
-
         for (name, extension) in user_exts {
             expander.cx.syntax_env.insert(name, extension);
         }
@@ -1220,7 +1223,7 @@ mod tests {
     use ast;
     use ast::Name;
     use codemap;
-    use ext::base::ExtCtxt;
+    use ext::base::{ExtCtxt, DummyMacroLoader};
     use ext::mtwt;
     use fold::Folder;
     use parse;
@@ -1291,9 +1294,9 @@ mod tests {
             src,
             Vec::new(), &sess).unwrap();
         // should fail:
-        let mut gated_cfgs = vec![];
-        let ecx = ExtCtxt::new(&sess, vec![], test_ecfg(), &mut gated_cfgs);
-        expand_crate(ecx, vec![], vec![], crate_ast);
+        let (mut gated_cfgs, mut loader) = (vec![], DummyMacroLoader);
+        let ecx = ExtCtxt::new(&sess, vec![], test_ecfg(), &mut gated_cfgs, &mut loader);
+        expand_crate(ecx, vec![], crate_ast);
     }
 
     // make sure that macros can't escape modules
@@ -1306,9 +1309,9 @@ mod tests {
             "<test>".to_string(),
             src,
             Vec::new(), &sess).unwrap();
-        let mut gated_cfgs = vec![];
-        let ecx = ExtCtxt::new(&sess, vec![], test_ecfg(), &mut gated_cfgs);
-        expand_crate(ecx, vec![], vec![], crate_ast);
+        let (mut gated_cfgs, mut loader) = (vec![], DummyMacroLoader);
+        let ecx = ExtCtxt::new(&sess, vec![], test_ecfg(), &mut gated_cfgs, &mut loader);
+        expand_crate(ecx, vec![], crate_ast);
     }
 
     // macro_use modules should allow macros to escape
@@ -1320,18 +1323,18 @@ mod tests {
             "<test>".to_string(),
             src,
             Vec::new(), &sess).unwrap();
-        let mut gated_cfgs = vec![];
-        let ecx = ExtCtxt::new(&sess, vec![], test_ecfg(), &mut gated_cfgs);
-        expand_crate(ecx, vec![], vec![], crate_ast);
+        let (mut gated_cfgs, mut loader) = (vec![], DummyMacroLoader);
+        let ecx = ExtCtxt::new(&sess, vec![], test_ecfg(), &mut gated_cfgs, &mut loader);
+        expand_crate(ecx, vec![], crate_ast);
     }
 
     fn expand_crate_str(crate_str: String) -> ast::Crate {
         let ps = parse::ParseSess::new();
         let crate_ast = panictry!(string_to_parser(&ps, crate_str).parse_crate_mod());
         // the cfg argument actually does matter, here...
-        let mut gated_cfgs = vec![];
-        let ecx = ExtCtxt::new(&ps, vec![], test_ecfg(), &mut gated_cfgs);
-        expand_crate(ecx, vec![], vec![], crate_ast).0
+        let (mut gated_cfgs, mut loader) = (vec![], DummyMacroLoader);
+        let ecx = ExtCtxt::new(&ps, vec![], test_ecfg(), &mut gated_cfgs, &mut loader);
+        expand_crate(ecx, vec![], crate_ast).0
     }
 
     // find the pat_ident paths in a crate
-- 
cgit 1.4.1-3-g733a5