Add -Z span_free_rvalues.

This is solely a hack to make comparing test output plausible; it
makes closures print as [closure@node_id] instead of
[closure@span-with-host-path] in debug printouts.

Author: pnkfelix

src/librustc/mir/mod.rs

@@ -1224,7 +1224,11 @@ impl<'tcx> Debug for Rvalue<'tcx> {
 
                     AggregateKind::Closure(def_id, _) => ty::tls::with(|tcx| {
                         if let Some(node_id) = tcx.hir.as_local_node_id(def_id) {
-                            let name = format!("[closure@{:?}]", tcx.hir.span(node_id));
+                            let name = if tcx.sess.opts.debugging_opts.span_free_formats {
+                                format!("[closure@{:?}]", node_id)
+                            } else {
+                                format!("[closure@{:?}]", tcx.hir.span(node_id))
+                            };
                             let mut struct_fmt = fmt.debug_struct(&name);
 
                             tcx.with_freevars(node_id, |freevars| {

src/librustc/session/config.rs

@@ -893,6 +893,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
          DB_OPTIONS, db_type_desc, dbsetters,
     verbose: bool = (false, parse_bool, [UNTRACKED],
         "in general, enable more debug printouts"),
+    span_free_formats: bool = (false, parse_bool, [UNTRACKED],
+        "when debug-printing compiler state, do not include spans"), // o/w tests have closure@path
     time_passes: bool = (false, parse_bool, [UNTRACKED],
         "measure time of each rustc pass"),
     count_llvm_insns: bool = (false, parse_bool,

src/librustc/util/ppaux.rs

@@ -789,7 +789,11 @@ impl<'tcx> fmt::Display for ty::TypeVariants<'tcx> {
                 write!(f, "[closure")?;
 
                 if let Some(node_id) = tcx.hir.as_local_node_id(did) {
-                    write!(f, "@{:?}", tcx.hir.span(node_id))?;
+                    if tcx.sess.opts.debugging_opts.span_free_formats {
+                        write!(f, "@{:?}", node_id)?;
+                    } else {
+                        write!(f, "@{:?}", tcx.hir.span(node_id))?;
+                    }
                     let mut sep = " ";
                     tcx.with_freevars(node_id, |freevars| {
                         for (freevar, upvar_ty) in freevars.iter().zip(upvar_tys) {