Attempt to fix hygiene for global_allocator

Author: mark-i-m

src/librustc_allocator/expand.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![allow(unused_imports, unused_variables, dead_code)]
+
 use rustc::middle::allocator::AllocatorKind;
 use rustc_errors;
 use rustc_target::spec::abi::Abi;
@@ -35,13 +37,15 @@ pub fn modify(
     sess: &ParseSess,
     resolver: &mut Resolver,
     krate: Crate,
+    crate_name: String,
     handler: &rustc_errors::Handler,
 ) -> ast::Crate {
     ExpandAllocatorDirectives {
         handler,
         sess,
         resolver,
         found: false,
+        crate_name: Some(crate_name),
     }.fold_crate(krate)
 }
 
@@ -50,6 +54,7 @@ struct ExpandAllocatorDirectives<'a> {
     handler: &'a rustc_errors::Handler,
     sess: &'a ParseSess,
     resolver: &'a mut Resolver,
+    crate_name: Option<String>,
 }
 
 impl<'a> Folder for ExpandAllocatorDirectives<'a> {
@@ -78,9 +83,10 @@ impl<'a> Folder for ExpandAllocatorDirectives<'a> {
         }
         self.found = true;
 
+        // Create a fresh Mark for the new macro expansion we are about to do
         let mark = Mark::fresh(Mark::root());
         mark.set_expn_info(ExpnInfo {
-            call_site: DUMMY_SP,
+            call_site: item.span,
             callee: NameAndSpan {
                 format: MacroAttribute(Symbol::intern(name)),
                 span: None,
@@ -89,35 +95,34 @@ impl<'a> Folder for ExpandAllocatorDirectives<'a> {
                 edition: hygiene::default_edition(),
             },
         });
+
+        // Tie the span to the macro expansion info we just created
         let span = item.span.with_ctxt(SyntaxContext::empty().apply_mark(mark));
-        let ecfg = ExpansionConfig::default(name.to_string());
+
+        // Create an expansion config
+        let ecfg = ExpansionConfig::default(self.crate_name.take().unwrap());
+
+        // Generate a bunch of new items using the AllocFnFactory
         let mut f = AllocFnFactory {
             span,
             kind: AllocatorKind::Global,
             global: item.ident,
-            core: Ident::from_str("core"),
+            core: Ident::with_empty_ctxt(Symbol::gensym("core")),
             cx: ExtCtxt::new(self.sess, ecfg, self.resolver),
         };
-        let super_path = f.cx.path(f.span, vec![Ident::from_str("super"), f.global]);
-        let mut items = vec![
-            f.cx.item_extern_crate(f.span, f.core),
-            f.cx.item_use_simple(
-                f.span,
-                respan(f.span.shrink_to_lo(), VisibilityKind::Inherited),
-                super_path,
-            ),
-        ];
-        for method in ALLOCATOR_METHODS {
-            items.push(f.allocator_fn(method));
-        }
-        let name = f.kind.fn_name("allocator_abi");
-        let allocator_abi = Ident::with_empty_ctxt(Symbol::gensym(&name));
-        let module = f.cx.item_mod(span, span, allocator_abi, Vec::new(), items);
-        let module = f.cx.monotonic_expander().fold_item(module).pop().unwrap();
+
+        let extcore = {
+            let extcore = f.cx.item_extern_crate(item.span, f.core);
+            f.cx.monotonic_expander().fold_item(extcore).pop().unwrap()
+        };
 
         let mut ret = SmallVector::new();
         ret.push(item);
-        ret.push(module);
+        ret.push(extcore);
+        ret.extend(ALLOCATOR_METHODS.iter().map(|method| {
+            let method = f.allocator_fn(method);
+            f.cx.monotonic_expander().fold_item(method).pop().unwrap()
+        }));
         return ret;
     }
 
@@ -170,6 +175,7 @@ impl<'a> AllocFnFactory<'a> {
         let method = self.cx.path(
             self.span,
             vec![
+                Ident::from_str("self"),
                 self.core,
                 Ident::from_str("alloc"),
                 Ident::from_str("GlobalAlloc"),
@@ -220,6 +226,7 @@ impl<'a> AllocFnFactory<'a> {
                 let layout_new = self.cx.path(
                     self.span,
                     vec![
+                        Ident::from_str("self"),
                         self.core,
                         Ident::from_str("alloc"),
                         Ident::from_str("Layout"),

src/librustc_driver/driver.rs

@@ -1051,10 +1051,19 @@ where
         });
     }
 
+    // Expand global allocators, which are treated as an in-tree proc macro
     krate = time(sess, "creating allocators", || {
-        allocator::expand::modify(&sess.parse_sess, &mut resolver, krate, sess.diagnostic())
+        allocator::expand::modify(
+            &sess.parse_sess,
+            &mut resolver,
+            krate,
+            crate_name.to_string(),
+            sess.diagnostic(),
+        )
     });
 
+    // Done with macro expansion!
+
     after_expand(&krate)?;
 
     if sess.opts.debugging_opts.input_stats {

src/test/ui/allocator-submodule.rs

@@ -0,0 +1,37 @@
+// Copyright 2015 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.
+
+// Tests that it is possible to create a global allocator in a submodule, rather than in the crate
+// root.
+
+#![feature(alloc, allocator_api, global_allocator)]
+
+extern crate alloc;
+
+use std::alloc::{GlobalAlloc, Layout, Opaque};
+
+struct MyAlloc;
+
+unsafe impl GlobalAlloc for MyAlloc {
+    unsafe fn alloc(&self, layout: Layout) -> *mut Opaque {
+        0 as usize as *mut Opaque
+    }
+
+    unsafe fn dealloc(&self, ptr: *mut Opaque, layout: Layout) {}
+}
+
+mod submod {
+    use super::MyAlloc;
+
+    #[global_allocator]
+    static MY_HEAP: MyAlloc = MyAlloc;
+}
+
+fn main() {}