warn the unused associated functions

4 files changed, 76 insertions, 15 deletions

diff --git a/gcc/rust/lint/rust-lint-marklive.cc b/gcc/rust/lint/rust-lint-marklive.cc
index 8339345..87fa3ef 100644
--- a/gcc/rust/lint/rust-lint-marklive.cc
+++ b/gcc/rust/lint/rust-lint-marklive.cc
@@ -106,11 +106,42 @@ MarkLive::go (HIR::Crate &crate)
 void
 MarkLive::visit (HIR::PathInExpression &expr)
 {
-  // We should iterate every path segment in order to mark the function which is
-  // called in the expression
+  // We should iterate every path segment in order to mark the struct which
+  // is used in expression like Foo::bar(), we should mark the Foo alive.
   expr.iterate_path_segments ([&] (HIR::PathExprSegment &seg) -> bool {
     return visit_path_segment (seg);
   });
+
+  // after iterate the path segments, we should mark functions and associated
+  // functions alive.
+  NodeId ast_node_id = expr.get_mappings ().get_nodeid ();
+  NodeId ref_node_id = UNKNOWN_NODEID;
+  find_ref_node_id (ast_node_id, ref_node_id);
+
+  // node back to HIR
+  HirId ref;
+  bool ok = mappings->lookup_node_to_hir (expr.get_mappings ().get_crate_num (),
+					  ref_node_id, &ref);
+  rust_assert (ok);
+
+  // it must resolve to some kind of HIR::Item or HIR::InheritImplItem
+  HIR::Item *resolved_item
+    = mappings->lookup_hir_item (expr.get_mappings ().get_crate_num (), ref);
+  if (resolved_item != nullptr)
+    {
+      mark_hir_id (resolved_item->get_mappings ().get_hirid ());
+    }
+  else
+    {
+      HirId parent_impl_id = UNKNOWN_HIRID;
+      HIR::ImplItem *resolved_item
+	= mappings->lookup_hir_implitem (expr.get_mappings ().get_crate_num (),
+					 ref, &parent_impl_id);
+      if (resolved_item != nullptr)
+	{
+	  mark_hir_id (resolved_item->get_impl_mappings ().get_hirid ());
+	}
+    }
 }
 
 void
@@ -126,8 +157,7 @@ MarkLive::visit (HIR::MethodCallExpr &expr)
   // Trying to find the method definition and mark it alive.
   NodeId ast_node_id = expr.get_mappings ().get_nodeid ();
   NodeId ref_node_id = UNKNOWN_NODEID;
-  find_ref_node_id (ast_node_id, ref_node_id, expr.get_locus (),
-		    expr.as_string ());
+  find_ref_node_id (ast_node_id, ref_node_id);
 
   // node back to HIR
   HirId ref;
@@ -215,8 +245,7 @@ MarkLive::visit (HIR::IdentifierExpr &expr)
 {
   NodeId ast_node_id = expr.get_mappings ().get_nodeid ();
   NodeId ref_node_id = UNKNOWN_NODEID;
-  find_ref_node_id (ast_node_id, ref_node_id, expr.get_locus (),
-		    expr.as_string ());
+  find_ref_node_id (ast_node_id, ref_node_id);
 
   // node back to HIR
   HirId ref;
@@ -251,8 +280,7 @@ MarkLive::mark_hir_id (HirId id)
 }
 
 void
-MarkLive::find_ref_node_id (NodeId ast_node_id, NodeId &ref_node_id,
-			    Location locus, const std::string &node_name)
+MarkLive::find_ref_node_id (NodeId ast_node_id, NodeId &ref_node_id)
 {
   if (resolver->lookup_resolved_name (ast_node_id, &ref_node_id))
     {
diff --git a/gcc/rust/lint/rust-lint-marklive.h b/gcc/rust/lint/rust-lint-marklive.h
index e6ca4ae..780b264 100644
--- a/gcc/rust/lint/rust-lint-marklive.h
+++ b/gcc/rust/lint/rust-lint-marklive.h
@@ -267,8 +267,7 @@ private:
 
   void mark_hir_id (HirId);
   bool visit_path_segment (HIR::PathExprSegment);
-  void find_ref_node_id (NodeId ast_node_id, NodeId &ref_node_id,
-			 Location locus, const std::string &node_name);
+  void find_ref_node_id (NodeId ast_node_id, NodeId &ref_node_id);
 };
 
 } // namespace Analysis
diff --git a/gcc/rust/lint/rust-lint-scan-deadcode.h b/gcc/rust/lint/rust-lint-scan-deadcode.h
index 6cf6281..464852a 100644
--- a/gcc/rust/lint/rust-lint-scan-deadcode.h
+++ b/gcc/rust/lint/rust-lint-scan-deadcode.h
@@ -32,7 +32,7 @@ namespace Analysis {
 // Scan item symbols and warn the symbol if it is not in the live_symbols set.
 // There are three kinds of item we should handle in this pass.
 // 1. Function item
-// 2. TODO: The function item in the impl block without trait
+// 2. The function item in the impl block without trait
 // 3. StructStruct, e.g., `Struct Foo{one: 1, two: 2}`. Furthermore, the unused
 //    struct fields will be warned too.
 // 4. TupleStruct, e.g., `Struct Foo(i32, i32)`
@@ -56,9 +56,23 @@ public:
     HirId hirId = function.get_mappings ().get_hirid ();
     if (should_warn (hirId))
       {
-	rust_warning_at (function.get_locus (), 0,
-			 "function is never used: %<%s%>",
-			 function.get_function_name ().c_str ());
+	if (mappings->is_impl_item (hirId))
+	  {
+	    HIR::ImplBlock *implBlock
+	      = mappings->lookup_associated_impl (hirId);
+	    if (!implBlock->has_trait_ref ())
+	      {
+		rust_warning_at (function.get_locus (), 0,
+				 "associated function is never used: %<%s%>",
+				 function.get_function_name ().c_str ());
+	      }
+	  }
+	else
+	  {
+	    rust_warning_at (function.get_locus (), 0,
+			     "function is never used: %<%s%>",
+			     function.get_function_name ().c_str ());
+	  }
       }
   }
 
@@ -99,12 +113,25 @@ public:
       }
   }
 
+  void visit (HIR::ImplBlock &blc) override
+  {
+    if (blc.has_impl_items ())
+      {
+	for (auto &implItem : blc.get_impl_items ())
+	  {
+	    implItem->accept_vis (*this);
+	  }
+      }
+  }
+
 private:
   std::set<HirId> live_symbols;
   Resolver::Resolver *resolver;
+  Analysis::Mappings *mappings;
 
   ScanDeadcode (std::set<HirId> &live_symbols)
-    : live_symbols (live_symbols), resolver (Resolver::Resolver::get ()){};
+    : live_symbols (live_symbols), resolver (Resolver::Resolver::get ()),
+      mappings (Analysis::Mappings::get ()){};
 
   bool should_warn (HirId hirId)
   {
diff --git a/gcc/rust/util/rust-hir-map.h b/gcc/rust/util/rust-hir-map.h
index cb3f12b..9b67928 100644
--- a/gcc/rust/util/rust-hir-map.h
+++ b/gcc/rust/util/rust-hir-map.h
@@ -194,6 +194,13 @@ public:
   void iterate_impl_items (
     std::function<bool (HirId, HIR::ImplItem *, HIR::ImplBlock *)> cb);
 
+  bool is_impl_item (HirId id)
+  {
+    HirId parent_impl_block_id = UNKNOWN_HIRID;
+    return lookup_hir_implitem (get_current_crate (), id, &parent_impl_block_id)
+	   != nullptr;
+  }
+
 private:
   Mappings ();