Fix ICE on missing TypeParam within type context

During type-resolution we resolve/type-check traits in a query based way.
So when we reference a trait we look it up as required but this left a case
for the privacy pass where the type-context information on the trait when
the trait was not used meant there was no type-checking performed on the
trait.

This patch adds an interface to directly resolve the trait when as we
iterate the crate so we do it as required. There is already code in the
trait resolver to check if we have already type-resolved this trait.

Fixes #1128

Author: philberty

gcc/rust/typecheck/rust-hir-trait-resolve.cc

@@ -74,7 +74,14 @@ TraitReference *
 TraitResolver::Resolve (HIR::TypePath &path)
 {
   TraitResolver resolver;
-  return resolver.go (path);
+  return resolver.resolve_path (path);
+}
+
+TraitReference *
+TraitResolver::Resolve (HIR::Trait &trait)
+{
+  TraitResolver resolver;
+  return resolver.resolve_trait (&trait);
 }
 
 TraitReference *
@@ -84,10 +91,12 @@ TraitResolver::Lookup (HIR::TypePath &path)
   return resolver.lookup_path (path);
 }
 
-TraitResolver::TraitResolver () : TypeCheckBase () {}
+TraitResolver::TraitResolver ()
+  : TypeCheckBase (), resolved_trait_reference (nullptr)
+{}
 
 TraitReference *
-TraitResolver::go (HIR::TypePath &path)
+TraitResolver::resolve_path (HIR::TypePath &path)
 {
   NodeId ref;
   if (!resolver->lookup_resolved_type (path.get_mappings ().get_nodeid (),
@@ -110,8 +119,14 @@ TraitResolver::go (HIR::TypePath &path)
 
   rust_assert (resolved_item != nullptr);
   resolved_item->accept_vis (*this);
-  rust_assert (trait_reference != nullptr);
+  rust_assert (resolved_trait_reference != nullptr);
 
+  return resolve_trait (resolved_trait_reference);
+}
+
+TraitReference *
+TraitResolver::resolve_trait (HIR::Trait *trait_reference)
+{
   TraitReference *tref = &TraitReference::error_node ();
   if (context->lookup_trait_reference (
 	trait_reference->get_mappings ().get_defid (), &tref))
@@ -243,11 +258,11 @@ TraitResolver::lookup_path (HIR::TypePath &path)
 
   rust_assert (resolved_item != nullptr);
   resolved_item->accept_vis (*this);
-  rust_assert (trait_reference != nullptr);
+  rust_assert (resolved_trait_reference != nullptr);
 
   TraitReference *tref = &TraitReference::error_node ();
   if (context->lookup_trait_reference (
-	trait_reference->get_mappings ().get_defid (), &tref))
+	resolved_trait_reference->get_mappings ().get_defid (), &tref))
     {
       return tref;
     }

gcc/rust/typecheck/rust-hir-trait-resolve.h

@@ -66,19 +66,23 @@ class TraitResolver : public TypeCheckBase
 public:
   static TraitReference *Resolve (HIR::TypePath &path);
 
+  static TraitReference *Resolve (HIR::Trait &trait);
+
   static TraitReference *Lookup (HIR::TypePath &path);
 
 private:
   TraitResolver ();
 
-  TraitReference *go (HIR::TypePath &path);
+  TraitReference *resolve_path (HIR::TypePath &path);
+
+  TraitReference *resolve_trait (HIR::Trait *trait_reference);
 
   TraitReference *lookup_path (HIR::TypePath &path);
 
-  HIR::Trait *trait_reference;
+  HIR::Trait *resolved_trait_reference;
 
 public:
-  void visit (HIR::Trait &trait) override { trait_reference = &trait; }
+  void visit (HIR::Trait &trait) override { resolved_trait_reference = &trait; }
 };
 
 } // namespace Resolver

gcc/rust/typecheck/rust-hir-type-check-item.h

@@ -224,6 +224,8 @@ class TypeCheckItem : public TypeCheckBase
       TypeCheckItem::Resolve (item.get ());
   }
 
+  void visit (HIR::Trait &trait) override { TraitResolver::Resolve (trait); }
+
 private:
   TypeCheckItem () : TypeCheckBase () {}
 };

gcc/testsuite/rust/compile/issue-1128.rs

@@ -0,0 +1,6 @@
+pub trait Hasher {
+    fn write(&mut self, bytes: &[u8]);
+    fn write_u8(&mut self, i: u8) {
+        self.write(&[i])
+    }
+}