Factor out some shared code.

`global_allocator_spans` and `alloc_error_handler_span` are identical
except for `name`.

Author: nnethercote

compiler/rustc_metadata/src/creader.rs

@@ -1032,14 +1032,19 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
 }
 
 fninject_allocator_crate(&mutself,krate:&ast::Crate){
-self.cstore.has_global_allocator = match&*global_allocator_spans(krate){
-[span1, span2, ..] => {
-self.dcx().emit_err(errors::NoMultipleGlobalAlloc{span2:*span2,span1:*span1 });
-true
-}
- spans => !spans.is_empty(),
-};
-self.cstore.has_alloc_error_handler = match&*alloc_error_handler_spans(krate){
+self.cstore.has_global_allocator =
+match&*fn_spans(krate,Symbol::intern(&global_fn_name(sym::alloc))){
+[span1, span2, ..] => {
+self.dcx()
+.emit_err(errors::NoMultipleGlobalAlloc{span2:*span2,span1:*span1 });
+true
+}
+ spans => !spans.is_empty(),
+};
+self.cstore.has_alloc_error_handler = match&*fn_spans(
+ krate,
+Symbol::intern(alloc_error_handler_name(AllocatorKind::Global)),
+){
 [span1, span2, ..] => {
 self.dcx()
 .emit_err(errors::NoMultipleAllocErrorHandler{span2:*span2,span1:*span1 });
@@ -1368,29 +1373,7 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
 }
 }
 
-fnglobal_allocator_spans(krate:&ast::Crate) -> Vec<Span>{
-structFinder{
-name:Symbol,
-spans:Vec<Span>,
-}
-impl<'ast> visit::Visitor<'ast>forFinder{
-fnvisit_item(&mutself,item:&'ast ast::Item){
-if item.ident.name == self.name
- && attr::contains_name(&item.attrs, sym::rustc_std_internal_symbol)
-{
-self.spans.push(item.span);
-}
- visit::walk_item(self, item)
-}
-}
-
-let name = Symbol::intern(&global_fn_name(sym::alloc));
-letmut f = Finder{ name,spans:Vec::new()};
- visit::walk_crate(&mut f, krate);
- f.spans
-}
-
-fnalloc_error_handler_spans(krate:&ast::Crate) -> Vec<Span>{
+fnfn_spans(krate:&ast::Crate,name:Symbol) -> Vec<Span>{
 structFinder{
 name:Symbol,
 spans:Vec<Span>,
@@ -1406,7 +1389,6 @@ fn alloc_error_handler_spans(krate: &ast::Crate) -> Vec<Span> {
 }
 }
 
-let name = Symbol::intern(alloc_error_handler_name(AllocatorKind::Global));
 letmut f = Finder{ name,spans:Vec::new()};
  visit::walk_crate(&mut f, krate);
  f.spans