perf: Reduce snapshot/rollback overhead

[rust.git] / src / librustc_infer / infer / error_reporting / need_type_info.rs

diff --git a/src/librustc_infer/infer/error_reporting/need_type_info.rs b/src/librustc_infer/infer/error_reporting/need_type_info.rs
index 1986838e4016c97af94c3fb01a56f766b23aef1e..d8133c58df7eb4d37d4d1a5d79cd309e208e3399 100644 (file)
--- a/src/librustc_infer/infer/error_reporting/need_type_info.rs
+++ b/src/librustc_infer/infer/error_reporting/need_type_info.rs
@@ -59,7 +59,7 @@ fn node_ty_contains_target(&mut self, hir_id: HirId) -> Option<Ty<'tcx>> {
                                         .infcx
                                         .inner
                                         .borrow_mut()
-                                        .type_variables
+                                        .type_variables()
                                         .sub_unified(a_vid, b_vid),
                                     _ => false,
                                 }
@@ -194,7 +194,8 @@ pub fn extract_type_name(
         highlight: Option<ty::print::RegionHighlightMode>,
     ) -> (String, Option<Span>, Cow<'static, str>, Option<String>, Option<&'static str>) {
         if let ty::Infer(ty::TyVar(ty_vid)) = ty.kind {
-            let ty_vars = &self.inner.borrow().type_variables;
+            let mut inner = self.inner.borrow_mut();
+            let ty_vars = &inner.type_variables();
             let var_origin = ty_vars.var_origin(ty_vid);
             if let TypeVariableOriginKind::TypeParameterDefinition(name, def_id) = var_origin.kind {
                 let parent_def_id = def_id.and_then(|def_id| self.tcx.parent(def_id));
@@ -248,7 +249,8 @@ pub fn need_type_info_err(
         let ty_to_string = |ty: Ty<'tcx>| -> String {
             let mut s = String::new();
             let mut printer = ty::print::FmtPrinter::new(self.tcx, &mut s, Namespace::TypeNS);
-            let ty_vars = &self.inner.borrow().type_variables;
+            let mut inner = self.inner.borrow_mut();
+            let ty_vars = inner.type_variables();
             let getter = move |ty_vid| {
                 let var_origin = ty_vars.var_origin(ty_vid);
                 if let TypeVariableOriginKind::TypeParameterDefinition(name, _) = var_origin.kind {
@@ -257,7 +259,13 @@ pub fn need_type_info_err(
                 None
             };
             printer.name_resolver = Some(Box::new(&getter));
-            let _ = ty.print(printer);
+            let _ = if let ty::FnDef(..) = ty.kind {
+                // We don't want the regular output for `fn`s because it includes its path in
+                // invalid pseduo-syntax, we want the `fn`-pointer output instead.
+                ty.fn_sig(self.tcx).print(printer)
+            } else {
+                ty.print(printer)
+            };
             s
         };