Check the invariant for `principal` inside the method

4 files changed, 18 insertions, 29 deletions

diff --git a/src/librustc_codegen_llvm/context.rs b/src/librustc_codegen_llvm/context.rs
index 578018c7adc..e6197423738 100644
--- a/src/librustc_codegen_llvm/context.rs
+++ b/src/librustc_codegen_llvm/context.rs
@@ -59,7 +59,7 @@ pub struct CodegenCx<'a, 'tcx: 'a> {
     /// Cache instances of monomorphic and polymorphic items
     pub instances: RefCell<FxHashMap<Instance<'tcx>, &'a Value>>,
     /// Cache generated vtables
-    pub vtables: RefCell<FxHashMap<(Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>),
+    pub vtables: RefCell<FxHashMap<(Ty<'tcx>, ty::PolyExistentialTraitRef<'tcx>),
                                    &'a Value>>,
     /// Cache of constant strings,
     pub const_cstr_cache: RefCell<FxHashMap<LocalInternedString, &'a Value>>,
diff --git a/src/librustc_codegen_llvm/debuginfo/metadata.rs b/src/librustc_codegen_llvm/debuginfo/metadata.rs
index 706568b5446..6eff086a2ba 100644
--- a/src/librustc_codegen_llvm/debuginfo/metadata.rs
+++ b/src/librustc_codegen_llvm/debuginfo/metadata.rs
@@ -435,12 +435,7 @@ fn trait_pointer_metadata(
     // But it does not describe the trait's methods.
 
     let containing_scope = match trait_type.sty {
-        ty::Dynamic(ref data, ..) => if let Some(principal) = data.principal() {
-            let def_id = principal.def_id();
-            Some(get_namespace_for_item(cx, def_id))
-        } else {
-            NO_SCOPE_METADATA
-        },
+        ty::Dynamic(ref data, ..) => Some(get_namespace_for_item(cx, data.principal().def_id())),
         _ => {
             bug!("debuginfo: Unexpected trait-object type in \
                   trait_pointer_metadata(): {:?}",
diff --git a/src/librustc_codegen_llvm/debuginfo/type_names.rs b/src/librustc_codegen_llvm/debuginfo/type_names.rs
index 2f110fd552a..06b9318a5e8 100644
--- a/src/librustc_codegen_llvm/debuginfo/type_names.rs
+++ b/src/librustc_codegen_llvm/debuginfo/type_names.rs
@@ -116,14 +116,12 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
             }
         },
         ty::Dynamic(ref trait_data, ..) => {
-            if let Some(principal) = trait_data.principal() {
-                let principal = cx.tcx.normalize_erasing_late_bound_regions(
-                    ty::ParamEnv::reveal_all(),
-                    &principal,
-                );
-                push_item_name(cx, principal.def_id, false, output);
-                push_type_params(cx, principal.substs, output);
-            }
+            let principal = cx.tcx.normalize_erasing_late_bound_regions(
+                ty::ParamEnv::reveal_all(),
+                &trait_data.principal(),
+            );
+            push_item_name(cx, principal.def_id, false, output);
+            push_type_params(cx, principal.substs, output);
         },
         ty::FnDef(..) | ty::FnPtr(_) => {
             let sig = t.fn_sig(cx.tcx);
diff --git a/src/librustc_codegen_llvm/meth.rs b/src/librustc_codegen_llvm/meth.rs
index 8a1159bc477..db06b87f44e 100644
--- a/src/librustc_codegen_llvm/meth.rs
+++ b/src/librustc_codegen_llvm/meth.rs
@@ -72,7 +72,7 @@ impl<'a, 'tcx> VirtualIndex {
 pub fn get_vtable(
     cx: &CodegenCx<'ll, 'tcx>,
     ty: Ty<'tcx>,
-    trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
+    trait_ref: ty::PolyExistentialTraitRef<'tcx>,
 ) -> &'ll Value {
     let tcx = cx.tcx;
 
@@ -86,23 +86,19 @@ pub fn get_vtable(
     // Not in the cache. Build it.
     let nullptr = C_null(Type::i8p(cx));
 
+    let methods = tcx.vtable_methods(trait_ref.with_self_ty(tcx, ty));
+    let methods = methods.iter().cloned().map(|opt_mth| {
+        opt_mth.map_or(nullptr, |(def_id, substs)| {
+            callee::resolve_and_get_fn(cx, def_id, substs)
+        })
+    });
+
     let (size, align) = cx.size_and_align_of(ty);
-    let mut components: Vec<_> = [
+    let components: Vec<_> = [
         callee::get_fn(cx, monomorphize::resolve_drop_in_place(cx.tcx, ty)),
         C_usize(cx, size.bytes()),
         C_usize(cx, align.abi())
-    ].iter().cloned().collect();
-
-    if let Some(trait_ref) = trait_ref {
-        let trait_ref = trait_ref.with_self_ty(tcx, ty);
-        let methods = tcx.vtable_methods(trait_ref);
-        let methods = methods.iter().cloned().map(|opt_mth| {
-            opt_mth.map_or(nullptr, |(def_id, substs)| {
-                callee::resolve_and_get_fn(cx, def_id, substs)
-            })
-        });
-        components.extend(methods);
-    }
+    ].iter().cloned().chain(methods).collect();
 
     let vtable_const = C_struct(cx, &components, false);
     let align = cx.data_layout().pointer_align;