AST/HIR: Clarify what the optional name in extern crate items mean

6 files changed, 17 insertions, 30 deletions

diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index 8b3a7164ccc..7ced6424824 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -2055,7 +2055,7 @@ pub struct Item {
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub enum ItemKind {
-    /// An `extern crate` item, with optional original crate name.
+    /// An `extern crate` item, with optional *original* crate name if the crate was renamed.
     ///
     /// E.g. `extern crate foo` or `extern crate foo_bar as foo`
     ExternCrate(Option<Name>),
diff --git a/src/libsyntax/fold.rs b/src/libsyntax/fold.rs
index 2cf99e15d1f..1a65fb7639a 100644
--- a/src/libsyntax/fold.rs
+++ b/src/libsyntax/fold.rs
@@ -886,7 +886,7 @@ pub fn noop_fold_block<T: Folder>(b: P<Block>, folder: &mut T) -> P<Block> {
 
 pub fn noop_fold_item_kind<T: Folder>(i: ItemKind, folder: &mut T) -> ItemKind {
     match i {
-        ItemKind::ExternCrate(string) => ItemKind::ExternCrate(string),
+        ItemKind::ExternCrate(orig_name) => ItemKind::ExternCrate(orig_name),
         ItemKind::Use(use_tree) => {
             ItemKind::Use(use_tree.map(|tree| folder.fold_use_tree(tree)))
         }
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index a3a6489fe8b..d1234d25764 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -6291,23 +6291,17 @@ impl<'a> Parser<'a> {
                                lo: Span,
                                visibility: Visibility,
                                attrs: Vec<Attribute>)
-                                -> PResult<'a, P<Item>> {
-
-        let crate_name = self.parse_ident()?;
-        let (maybe_path, ident) = if let Some(ident) = self.parse_rename()? {
-            (Some(crate_name.name), ident)
+                               -> PResult<'a, P<Item>> {
+        let orig_name = self.parse_ident()?;
+        let (item_name, orig_name) = if let Some(rename) = self.parse_rename()? {
+            (rename, Some(orig_name.name))
         } else {
-            (None, crate_name)
+            (orig_name, None)
         };
         self.expect(&token::Semi)?;
 
-        let prev_span = self.prev_span;
-
-        Ok(self.mk_item(lo.to(prev_span),
-                        ident,
-                        ItemKind::ExternCrate(maybe_path),
-                        visibility,
-                        attrs))
+        let span = lo.to(self.prev_span);
+        Ok(self.mk_item(span, item_name, ItemKind::ExternCrate(orig_name), visibility, attrs))
     }
 
     /// Parse `extern` for foreign ABIs
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 1cf2b7a44bc..097c0fd16d0 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -1174,15 +1174,10 @@ impl<'a> State<'a> {
         self.print_outer_attributes(&item.attrs)?;
         self.ann.pre(self, NodeItem(item))?;
         match item.node {
-            ast::ItemKind::ExternCrate(ref optional_path) => {
+            ast::ItemKind::ExternCrate(orig_name) => {
                 self.head(&visibility_qualified(&item.vis, "extern crate"))?;
-                if let Some(p) = *optional_path {
-                    let val = p.as_str();
-                    if val.contains('-') {
-                        self.print_string(&val, ast::StrStyle::Cooked)?;
-                    } else {
-                        self.print_name(p)?;
-                    }
+                if let Some(orig_name) = orig_name {
+                    self.print_name(orig_name)?;
                     self.s.space()?;
                     self.s.word("as")?;
                     self.s.space()?;
diff --git a/src/libsyntax/std_inject.rs b/src/libsyntax/std_inject.rs
index da24107f4c3..59425929f7e 100644
--- a/src/libsyntax/std_inject.rs
+++ b/src/libsyntax/std_inject.rs
@@ -43,7 +43,7 @@ thread_local! {
     static INJECTED_CRATE_NAME: Cell<Option<&'static str>> = Cell::new(None);
 }
 
-pub fn maybe_inject_crates_ref(mut krate: ast::Crate, alt_std_name: Option<String>) -> ast::Crate {
+pub fn maybe_inject_crates_ref(mut krate: ast::Crate, alt_std_name: Option<&str>) -> ast::Crate {
     let name = if attr::contains_name(&krate.attrs, "no_core") {
         return krate;
     } else if attr::contains_name(&krate.attrs, "no_std") {
@@ -54,14 +54,12 @@ pub fn maybe_inject_crates_ref(mut krate: ast::Crate, alt_std_name: Option<Strin
 
     INJECTED_CRATE_NAME.with(|opt_name| opt_name.set(Some(name)));
 
-    let crate_name = Symbol::intern(&alt_std_name.unwrap_or_else(|| name.to_string()));
-
     krate.module.items.insert(0, P(ast::Item {
         attrs: vec![attr::mk_attr_outer(DUMMY_SP,
                                         attr::mk_attr_id(),
                                         attr::mk_word_item(Symbol::intern("macro_use")))],
         vis: dummy_spanned(ast::VisibilityKind::Inherited),
-        node: ast::ItemKind::ExternCrate(Some(crate_name)),
+        node: ast::ItemKind::ExternCrate(alt_std_name.map(Symbol::intern)),
         ident: ast::Ident::from_str(name),
         id: ast::DUMMY_NODE_ID,
         span: DUMMY_SP,
diff --git a/src/libsyntax/visit.rs b/src/libsyntax/visit.rs
index 5a24c61cb5a..3bf9bfab245 100644
--- a/src/libsyntax/visit.rs
+++ b/src/libsyntax/visit.rs
@@ -213,9 +213,9 @@ pub fn walk_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a Item) {
     visitor.visit_vis(&item.vis);
     visitor.visit_ident(item.span, item.ident);
     match item.node {
-        ItemKind::ExternCrate(opt_name) => {
-            if let Some(name) = opt_name {
-                visitor.visit_name(item.span, name);
+        ItemKind::ExternCrate(orig_name) => {
+            if let Some(orig_name) = orig_name {
+                visitor.visit_name(item.span, orig_name);
             }
         }
         ItemKind::Use(ref use_tree) => {