Point at def span on incorrect panic or alloc error handler

src/librustc_typeck/check/mod.rs

@@ -1178,6 +1178,7 @@ fn check_fn<'a, 'gcx, 'tcx>(inherited: &'a Inherited<'a, 'gcx, 'tcx>,
                         }
                     }
                 } else {
+                    let span = fcx.tcx.sess.source_map().def_span(span);
                     fcx.tcx.sess.span_err(span, "function should have one argument");
                 }
             } else {
@@ -1226,6 +1227,7 @@ fn check_fn<'a, 'gcx, 'tcx>(inherited: &'a Inherited<'a, 'gcx, 'tcx>,
                         }
                     }
                 } else {
+                    let span = fcx.tcx.sess.source_map().def_span(span);
                     fcx.tcx.sess.span_err(span, "function should have one argument");
                 }
             } else {

src/test/ui/alloc-error/alloc-error-handler-bad-signature-3.stderr

@@ -1,10 +1,8 @@
 error: function should have one argument
   --> $DIR/alloc-error-handler-bad-signature-3.rs:20:1
    |
-LL | / fn oom() -> ! { //~ ERROR function should have one argument
-LL | |     loop {}
-LL | | }
-   | |_^
+LL | fn oom() -> ! { //~ ERROR function should have one argument
+   | ^^^^^^^^^^^^^
 
 error: aborting due to previous error
 

src/test/ui/panic-handler/panic-handler-bad-signature-3.stderr

@@ -1,10 +1,8 @@
 error: function should have one argument
   --> $DIR/panic-handler-bad-signature-3.rs:20:1
    |
-LL | / fn panic() -> ! { //~ ERROR function should have one argument
-LL | |     loop {}
-LL | | }
-   | |_^
+LL | fn panic() -> ! { //~ ERROR function should have one argument
+   | ^^^^^^^^^^^^^^^
 
 error: aborting due to previous error