Add own_requires_monomorphization

src/librustc/ty/mod.rs

@@ -934,12 +934,10 @@ impl<'a, 'gcx, 'tcx> Generics {
     }
 
     pub fn requires_monomorphization(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> bool {
-        for param in &self.params {
+        if self.own_requires_monomorphization() {
-            match param.kind {
+            return true;
-                GenericParamDefKind::Type { .. } | GenericParamDefKind::Const => return true,
-                GenericParamDefKind::Lifetime => {}
-            }
         }
+
         if let Some(parent_def_id) = self.parent {
             let parent = tcx.generics_of(parent_def_id);
             parent.requires_monomorphization(tcx)
@@ -948,6 +946,16 @@ impl<'a, 'gcx, 'tcx> Generics {
         }
     }
 
+    pub fn own_requires_monomorphization(&self) -> bool {
+        for param in &self.params {
+            match param.kind {
+                GenericParamDefKind::Type { .. } | GenericParamDefKind::Const => return true,
+                GenericParamDefKind::Lifetime => {}
+            }
+        }
+        false
+    }
+
     pub fn region_param(&'tcx self,
                         param: &EarlyBoundRegion,
                         tcx: TyCtxt<'a, 'gcx, 'tcx>)

src/librustc_mir/monomorphize/collector.rs

@@ -1135,8 +1135,7 @@ fn create_mono_items_for_default_impls<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                         continue;
                     }
 
-                    let counts = tcx.generics_of(method.def_id).own_counts();
+                    if tcx.generics_of(method.def_id).own_requires_monomorphization() {
-                    if counts.types + counts.consts != 0 {
                         continue;
                     }
 

src/librustc_mir/transform/check_unsafety.rs

@@ -560,8 +560,7 @@ fn unsafe_derive_on_repr_packed<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: D
 
     // FIXME: when we make this a hard error, this should have its
     // own error code.
-    let counts = tcx.generics_of(def_id).own_counts();
+    let message = if tcx.generics_of(def_id).own_requires_monomorphization() {
-    let message = if counts.types + counts.consts != 0 {
         "#[derive] can't be used on a #[repr(packed)] struct with \
          type or const parameters (error E0133)".to_string()
     } else {