Revert "Point macros 1.1 errors to the input item"

This reverts commit 3784067.
Any errors in the derived output now point at the derive attribute
instead of the item.

src/libsyntax_ext/deriving/custom.rs

@@ -14,12 +14,10 @@ use errors::FatalError;
 use proc_macro::{TokenStream, __internal};
 use syntax::ast::{self, ItemKind, Attribute};
 use syntax::attr::{mark_used, mark_known};
-use syntax::codemap::{ExpnInfo, MacroAttribute, NameAndSpan, Span};
+use syntax::codemap::Span;
 use syntax::ext::base::*;
 use syntax::fold::Folder;
 use syntax::parse::token::InternedString;
-use syntax::parse::token::intern;
-use syntax::print::pprust;
 use syntax::visit::Visitor;
 
 struct MarkAttrs<'a>(&'a [InternedString]);
@@ -50,7 +48,7 @@ impl MultiItemModifier for CustomDerive {
  fn expand(&self,
  ecx: &mut ExtCtxt,
  span: Span,
- meta_item: &ast::MetaItem,
+ _meta_item: &ast::MetaItem,
  item: Annotatable)
  -> Vec<Annotatable> {
  let item = match item {
@@ -75,18 +73,6 @@ impl MultiItemModifier for CustomDerive {
  // Mark attributes as known, and used.
  MarkAttrs(&self.attrs).visit_item(&item);
 
- let input_span = Span {
- expn_id: ecx.codemap().record_expansion(ExpnInfo {
- call_site: span,
- callee: NameAndSpan {
- format: MacroAttribute(intern(&pprust::meta_item_to_string(meta_item))),
- span: Some(span),
- allow_internal_unstable: true,
- },
- }),
- ..item.span
- };
-
  let input = __internal::new_token_stream(item.clone());
  let res = __internal::set_parse_sess(&ecx.parse_sess, || {
  let inner = self.inner;
@@ -113,7 +99,7 @@ impl MultiItemModifier for CustomDerive {
  // Reassign spans of all expanded items to the input `item`
  // for better errors here.
  res.extend(new_items.into_iter().flat_map(|item| {
- ChangeSpan { span: input_span }.fold_item(item)
+ ChangeSpan { span: span }.fold_item(item)
  }).map(Annotatable::Item));
  res
  }

src/test/compile-fail-fulldeps/proc-macro/expand-to-unstable-2.rs

@@ -17,8 +17,8 @@
 extern crate derive_unstable_2;
 
 #[derive(Unstable)]
-struct A;
 //~^ ERROR: reserved for internal compiler
+struct A;
 
 fn main() {
  foo();

src/test/compile-fail-fulldeps/proc-macro/expand-to-unstable.rs

@@ -17,8 +17,8 @@
 extern crate derive_unstable;
 
 #[derive(Unstable)]
-struct A;
 //~^ ERROR: use of unstable library feature
+struct A;
 
 fn main() {
  unsafe { foo(); }