detect unused struct field.

25 files changed, 207 insertions, 63 deletions

diff --git a/gcc/rust/lint/rust-lint-marklive.cc b/gcc/rust/lint/rust-lint-marklive.cc
index 5cdb5d4..af871a5 100644
--- a/gcc/rust/lint/rust-lint-marklive.cc
+++ b/gcc/rust/lint/rust-lint-marklive.cc
@@ -92,89 +92,156 @@ void
 MarkLive::visit (HIR::PathInExpression &expr)
 {
   expr.iterate_path_segments ([&] (HIR::PathExprSegment &seg) -> bool {
-    NodeId ast_node_id = seg.get_mappings ().get_nodeid ();
-    NodeId ref_node_id = UNKNOWN_NODEID;
-    HirId ref;
-    if (resolver->lookup_resolved_name (ast_node_id, &ref_node_id))
-      {
-	Resolver::Definition def;
-	if (!resolver->lookup_definition (ref_node_id, &def))
-	  {
-	    rust_error_at (seg.get_locus (),
-			   "unknown reference for resolved name");
-	    return false;
-	  }
-	ref_node_id = def.parent;
-      }
-    else if (!resolver->lookup_resolved_type (ast_node_id, &ref_node_id))
-      {
-	return false;
-      }
-
-    if (!mappings->lookup_node_to_hir (seg.get_mappings ().get_crate_num (),
-				       ref_node_id, &ref))
-      {
-	rust_error_at (seg.get_locus (), "reverse lookup failure");
-	return false;
-      }
-    if (scannedSymbols.find (ref) == scannedSymbols.end ())
-      {
-	worklist.push_back (ref);
-      }
-    liveSymbols.emplace (ref);
-    return true;
+    return visit_path_segment (seg);
   });
 }
 
 void
-MarkLive::visit (HIR::IdentifierExpr &expr)
+MarkLive::visit (HIR::MethodCallExpr &expr)
 {
+  expr.get_receiver ()->accept_vis (*this);
+  visit_path_segment (expr.get_method_name ());
+  expr.iterate_params ([&] (HIR::Expr *param) -> bool {
+    param->accept_vis (*this);
+    return true;
+  });
+
   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 ());
 
-  // then lookup the reference_node_id
+  // node back to HIR
+  HirId ref;
+  node_id_to_hir_id (expr.get_mappings ().get_crate_num (), ref_node_id, ref,
+		     expr.get_locus ());
+  mark_hir_id (ref);
+}
+
+bool
+MarkLive::visit_path_segment (HIR::PathExprSegment seg)
+{
+  NodeId ast_node_id = seg.get_mappings ().get_nodeid ();
   NodeId ref_node_id = UNKNOWN_NODEID;
   if (resolver->lookup_resolved_name (ast_node_id, &ref_node_id))
     {
-      // these ref_node_ids will resolve to a pattern declaration but we are
-      // interested in the definition that this refers to get the parent id
       Resolver::Definition def;
       if (!resolver->lookup_definition (ref_node_id, &def))
 	{
-	  rust_error_at (expr.get_locus (),
+	  rust_error_at (seg.get_locus (),
 			 "unknown reference for resolved name");
-	  return;
+	  return false;
 	}
       ref_node_id = def.parent;
     }
   else if (!resolver->lookup_resolved_type (ast_node_id, &ref_node_id))
     {
-      rust_error_at (expr.get_locus (),
-		     "Failed to lookup type reference for node: %s",
-		     expr.as_string ().c_str ());
-      return;
+      return false;
     }
+  HirId ref;
+  node_id_to_hir_id (seg.get_mappings ().get_crate_num (), ref_node_id, ref,
+		     seg.get_locus ());
+  mark_hir_id (ref);
+  return true;
+}
 
-  if (ref_node_id == UNKNOWN_NODEID)
+void
+MarkLive::visit (HIR::FieldAccessExpr &expr)
+{
+  // visit receiver at first
+  expr.get_receiver_expr ()->accept_vis (*this);
+
+  // resolve the receiver back to ADT type
+  TyTy::BaseType *receiver = nullptr;
+  if (!tyctx->lookup_type (
+	expr.get_receiver_expr ()->get_mappings ().get_hirid (), &receiver))
+    {
+      rust_error_at (expr.get_receiver_expr ()->get_locus_slow (),
+		     "unresolved type for receiver");
+    }
+  rust_assert (receiver->get_kind () == TyTy::TypeKind::ADT);
+  TyTy::ADTType *adt = static_cast<TyTy::ADTType *> (receiver);
+
+  // get the field index
+  size_t index = 0;
+  adt->get_field (expr.get_field_name (), &index);
+  if (index >= adt->num_fields ())
     {
-      rust_error_at (expr.get_locus (), "unresolved node: %s",
-		     expr.as_string ().c_str ());
+      rust_error_at (expr.get_receiver_expr ()->get_locus_slow (),
+		     "cannot access struct %s by index: %ld",
+		     adt->get_name ().c_str (), index);
       return;
     }
+  // get the field hir id
+  HirId field_id = adt->get_field (index)->get_ref ();
+  mark_hir_id (field_id);
+}
+
+void
+MarkLive::visit (HIR::TupleIndexExpr &expr)
+{
+  // TODO: unused tuple field detection
+  expr.get_tuple_expr ()->accept_vis (*this);
+}
+
+void
+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 ());
 
   // node back to HIR
   HirId ref;
-  if (!mappings->lookup_node_to_hir (expr.get_mappings ().get_crate_num (),
-				     ref_node_id, &ref))
+  node_id_to_hir_id (expr.get_mappings ().get_crate_num (), ref_node_id, ref,
+		     expr.get_locus ());
+  mark_hir_id (ref);
+}
+
+void
+MarkLive::mark_hir_id (HirId id)
+{
+  if (scannedSymbols.find (id) == scannedSymbols.end ())
+    {
+      worklist.push_back (id);
+    }
+  liveSymbols.emplace (id);
+}
+
+void
+MarkLive::find_ref_node_id (NodeId ast_node_id, NodeId &ref_node_id,
+			    Location locus, const std::string &node_name)
+{
+  if (resolver->lookup_resolved_name (ast_node_id, &ref_node_id))
     {
-      rust_error_at (expr.get_locus (), "reverse lookup failure");
+      // these ref_node_ids will resolve to a pattern declaration but we are
+      // interested in the definition that this refers to get the parent id
+      Resolver::Definition def;
+      if (!resolver->lookup_definition (ref_node_id, &def))
+	{
+	  rust_error_at (locus, "unknown reference for resolved name");
+	  return;
+	}
+      ref_node_id = def.parent;
+    }
+  else if (!resolver->lookup_resolved_type (ast_node_id, &ref_node_id))
+    {
+      rust_error_at (locus, "Failed to lookup type reference for node: %s",
+		     node_name.c_str ());
       return;
     }
+}
 
-  if (scannedSymbols.find (ref) == scannedSymbols.end ())
+void
+MarkLive::node_id_to_hir_id (CrateNum crateNum, NodeId ref_node_id, HirId &ref,
+			     Location locus)
+{
+  if (!mappings->lookup_node_to_hir (crateNum, ref_node_id, &ref))
     {
-      worklist.push_back (ref);
+      rust_error_at (locus, "reverse lookup failure");
+      return;
     }
-  liveSymbols.emplace (ref);
 }
 
 } // namespace Analysis
diff --git a/gcc/rust/lint/rust-lint-marklive.h b/gcc/rust/lint/rust-lint-marklive.h
index 2db5294..72274d0 100644
--- a/gcc/rust/lint/rust-lint-marklive.h
+++ b/gcc/rust/lint/rust-lint-marklive.h
@@ -38,6 +38,9 @@ public:
 
   void visit (HIR::PathInExpression &expr) override;
   void visit (HIR::IdentifierExpr &expr) override;
+  void visit (HIR::FieldAccessExpr &expr) override;
+  void visit (HIR::TupleIndexExpr &expr) override;
+  void visit (HIR::MethodCallExpr &expr) override;
 
   void visit (HIR::BorrowExpr &expr) override
   {
@@ -156,6 +159,10 @@ public:
   void visit (HIR::CallExpr &expr) override
   {
     expr.get_fnexpr ()->accept_vis (*this);
+    expr.iterate_params ([&] (HIR::Expr *expr) -> bool {
+      expr->accept_vis (*this);
+      return true;
+    });
   }
 
   void visit (HIR::ArithmeticOrLogicalExpr &expr) override
@@ -226,9 +233,17 @@ private:
   std::set<HirId> scannedSymbols;
   Analysis::Mappings *mappings;
   Resolver::Resolver *resolver;
+  Resolver::TypeCheckContext *tyctx;
   MarkLive (std::vector<HirId> worklist)
     : worklist (worklist), mappings (Analysis::Mappings::get ()),
-      resolver (Resolver::Resolver::get ()){};
+      resolver (Resolver::Resolver::get ()),
+      tyctx (Resolver::TypeCheckContext::get ()){};
+
+  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 node_id_to_hir_id (CrateNum, NodeId, HirId &, Location);
 };
 
 } // namespace Analysis
diff --git a/gcc/rust/lint/rust-lint-scan-deadcode.h b/gcc/rust/lint/rust-lint-scan-deadcode.h
index 1dee18a..ad48a47 100644
--- a/gcc/rust/lint/rust-lint-scan-deadcode.h
+++ b/gcc/rust/lint/rust-lint-scan-deadcode.h
@@ -46,15 +46,37 @@ public:
   void visit (HIR::Function &function) override
   {
     HirId hirId = function.get_mappings ().get_hirid ();
-    warning (hirId, function.get_locus (), "function",
-	     function.get_function_name (), "used");
+    if (should_warn (hirId))
+      {
+	rust_warning_at (function.get_locus (), 0, "%s is never %s: %<%s%>",
+			 "function", "used",
+			 function.get_function_name ().c_str ());
+      }
   }
 
   void visit (HIR::StructStruct &stct) override
   {
     HirId hirId = stct.get_mappings ().get_hirid ();
-    warning (hirId, stct.get_locus (), "struct", stct.get_identifier (),
-	     "constructed");
+    if (should_warn (hirId))
+      {
+	rust_warning_at (stct.get_locus (), 0, "%s is never %s: %<%s%>",
+			 "struct", "constructed",
+			 stct.get_identifier ().c_str ());
+      }
+    else
+      {
+	// only warn the unused fields when in unwarned struct.
+	stct.iterate ([&] (HIR::StructField &field) -> bool {
+	  HirId field_hir_id = field.get_mappings ().get_hirid ();
+	  if (should_warn (field_hir_id))
+	    {
+	      rust_warning_at (field.get_locus (), 0, "%s is never %s: %<%s%>",
+			       "field", "read",
+			       field.get_field_name ().c_str ());
+	    }
+	  return true;
+	});
+      }
   }
 
 private:
@@ -64,15 +86,11 @@ private:
   ScanDeadcode (std::set<HirId> &live_symbols)
     : live_symbols (live_symbols), resolver (Resolver::Resolver::get ()){};
 
-  void warning (HirId hirId, Location loc, const std::string &span,
-		const std::string &name, const std::string &participle) const
+  bool should_warn (HirId hirId)
   {
-    if (live_symbols.find (hirId) == live_symbols.end ())
-      {
-	rust_warning_at (loc, 0, "%s is never %s: %<%s%>", span.c_str (),
-			 participle.c_str (), name.c_str ());
-	return;
-      }
+    // TODO: There are more condition to check if should warn, i.e visibility,
+    // attributes.
+    return live_symbols.find (hirId) == live_symbols.end ();
   }
 };
 
diff --git a/gcc/testsuite/rust/compile/torture/forward_decl_3.rs b/gcc/testsuite/rust/compile/torture/forward_decl_3.rs
index 0028ca5..9256df5 100644
--- a/gcc/testsuite/rust/compile/torture/forward_decl_3.rs
+++ b/gcc/testsuite/rust/compile/torture/forward_decl_3.rs
@@ -5,5 +5,7 @@ fn main() {
 
 struct Foo {
     one: i32,
+    // { dg-warning "field is never read" "" { target *-*-* } .-1 }
     two: i32,
+    // { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
diff --git a/gcc/testsuite/rust/compile/torture/generics10.rs b/gcc/testsuite/rust/compile/torture/generics10.rs
index 9526149..8473d49 100644
--- a/gcc/testsuite/rust/compile/torture/generics10.rs
+++ b/gcc/testsuite/rust/compile/torture/generics10.rs
@@ -3,6 +3,7 @@ struct Foo<T>(T);
 struct Bar<T> {
     a: Foo<T>,
     b: bool,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 fn test<T>(a: Bar<T>) -> Foo<T> {
diff --git a/gcc/testsuite/rust/compile/torture/generics13.rs b/gcc/testsuite/rust/compile/torture/generics13.rs
index 5c8795d..e924ab4 100644
--- a/gcc/testsuite/rust/compile/torture/generics13.rs
+++ b/gcc/testsuite/rust/compile/torture/generics13.rs
@@ -1,5 +1,6 @@
 struct Foo<A> {
     a: A,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 struct GenericStruct<T> {
diff --git a/gcc/testsuite/rust/compile/torture/generics14.rs b/gcc/testsuite/rust/compile/torture/generics14.rs
index aa8fbf2..0d2e390 100644
--- a/gcc/testsuite/rust/compile/torture/generics14.rs
+++ b/gcc/testsuite/rust/compile/torture/generics14.rs
@@ -1,5 +1,6 @@
 struct Foo<A> {
     a: A,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 impl Foo<isize> {
diff --git a/gcc/testsuite/rust/compile/torture/generics4.rs b/gcc/testsuite/rust/compile/torture/generics4.rs
index 3ae3861..915cc49 100644
--- a/gcc/testsuite/rust/compile/torture/generics4.rs
+++ b/gcc/testsuite/rust/compile/torture/generics4.rs
@@ -1,6 +1,8 @@
 struct Foo<T> {
     a: T,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
     b: bool,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 fn test<T>(a: T) -> Foo<T> {
diff --git a/gcc/testsuite/rust/compile/torture/generics6.rs b/gcc/testsuite/rust/compile/torture/generics6.rs
index 283a118..5456b6d 100644
--- a/gcc/testsuite/rust/compile/torture/generics6.rs
+++ b/gcc/testsuite/rust/compile/torture/generics6.rs
@@ -3,6 +3,7 @@ struct Foo<T>(T);
 struct Bar<T> {
     a: Foo<T>,
     b: bool,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 fn main() {
diff --git a/gcc/testsuite/rust/compile/torture/generics7.rs b/gcc/testsuite/rust/compile/torture/generics7.rs
index 2e89ce1..e8e5ca6 100644
--- a/gcc/testsuite/rust/compile/torture/generics7.rs
+++ b/gcc/testsuite/rust/compile/torture/generics7.rs
@@ -3,6 +3,7 @@ struct Foo<T>(T);
 struct Bar {
     a: Foo<i32>,
     b: bool,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 fn main() {
diff --git a/gcc/testsuite/rust/compile/torture/impl_block3.rs b/gcc/testsuite/rust/compile/torture/impl_block3.rs
index 78ec459..22ce19f 100644
--- a/gcc/testsuite/rust/compile/torture/impl_block3.rs
+++ b/gcc/testsuite/rust/compile/torture/impl_block3.rs
@@ -1,6 +1,8 @@
 struct Point {
     x: f64,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
     y: f64,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 impl Point {
@@ -15,7 +17,9 @@ impl Point {
 
 struct Rectangle {
     p1: Point,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
     p2: Point,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 impl Rectangle {
diff --git a/gcc/testsuite/rust/compile/torture/methods1.rs b/gcc/testsuite/rust/compile/torture/methods1.rs
index df3663f..a8e384d 100644
--- a/gcc/testsuite/rust/compile/torture/methods1.rs
+++ b/gcc/testsuite/rust/compile/torture/methods1.rs
@@ -1,6 +1,7 @@
 struct Point {
     x: f64,
     y: f64,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 impl Point {
diff --git a/gcc/testsuite/rust/compile/torture/methods2.rs b/gcc/testsuite/rust/compile/torture/methods2.rs
index 72ba29c..d63211b 100644
--- a/gcc/testsuite/rust/compile/torture/methods2.rs
+++ b/gcc/testsuite/rust/compile/torture/methods2.rs
@@ -1,6 +1,7 @@
 struct Point {
     x: f64,
     y: f64,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 impl Point {
diff --git a/gcc/testsuite/rust/compile/torture/methods3.rs b/gcc/testsuite/rust/compile/torture/methods3.rs
index b0cb78f..55426f4 100644
--- a/gcc/testsuite/rust/compile/torture/methods3.rs
+++ b/gcc/testsuite/rust/compile/torture/methods3.rs
@@ -1,6 +1,7 @@
 struct Point {
     x: f64,
     y: f64,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 impl Point {
diff --git a/gcc/testsuite/rust/compile/torture/nested_struct1.rs b/gcc/testsuite/rust/compile/torture/nested_struct1.rs
index 56ce053..2bd5ead 100644
--- a/gcc/testsuite/rust/compile/torture/nested_struct1.rs
+++ b/gcc/testsuite/rust/compile/torture/nested_struct1.rs
@@ -1,11 +1,13 @@
 struct Point {
     x: f64,
     y: f64,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 struct Rectangle {
     p1: Point,
     p2: Point,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 fn main() {
diff --git a/gcc/testsuite/rust/compile/torture/struct_base_init_1.rs b/gcc/testsuite/rust/compile/torture/struct_base_init_1.rs
index 3c0b24a..39dc61a 100644
--- a/gcc/testsuite/rust/compile/torture/struct_base_init_1.rs
+++ b/gcc/testsuite/rust/compile/torture/struct_base_init_1.rs
@@ -1,6 +1,8 @@
 struct Foo {
     a: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
     b: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 fn foo() -> Foo {
diff --git a/gcc/testsuite/rust/compile/torture/struct_init.rs b/gcc/testsuite/rust/compile/torture/struct_init.rs
index be0b963..1926f73 100644
--- a/gcc/testsuite/rust/compile/torture/struct_init.rs
+++ b/gcc/testsuite/rust/compile/torture/struct_init.rs
@@ -1,6 +1,8 @@
 struct Foo {
     one: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
     two: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 fn main() {
diff --git a/gcc/testsuite/rust/compile/torture/struct_init_3.rs b/gcc/testsuite/rust/compile/torture/struct_init_3.rs
index 5e52d09..1398f8e 100644
--- a/gcc/testsuite/rust/compile/torture/struct_init_3.rs
+++ b/gcc/testsuite/rust/compile/torture/struct_init_3.rs
@@ -1,6 +1,8 @@
 struct Foo {
     a: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
     b: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 fn main() {
diff --git a/gcc/testsuite/rust/compile/torture/struct_init_4.rs b/gcc/testsuite/rust/compile/torture/struct_init_4.rs
index 57b6bd4..d4b2de8 100644
--- a/gcc/testsuite/rust/compile/torture/struct_init_4.rs
+++ b/gcc/testsuite/rust/compile/torture/struct_init_4.rs
@@ -1,6 +1,8 @@
 struct Foo {
     a: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
     b: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 fn main() {
diff --git a/gcc/testsuite/rust/compile/torture/struct_init_5.rs b/gcc/testsuite/rust/compile/torture/struct_init_5.rs
index 891f645..e7f9d16 100644
--- a/gcc/testsuite/rust/compile/torture/struct_init_5.rs
+++ b/gcc/testsuite/rust/compile/torture/struct_init_5.rs
@@ -1,6 +1,8 @@
 struct Foo {
     a: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
     b: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 fn main() {
diff --git a/gcc/testsuite/rust/compile/torture/struct_init_6.rs b/gcc/testsuite/rust/compile/torture/struct_init_6.rs
index e7f8a12..9a6241a 100644
--- a/gcc/testsuite/rust/compile/torture/struct_init_6.rs
+++ b/gcc/testsuite/rust/compile/torture/struct_init_6.rs
@@ -1,6 +1,8 @@
 struct Foo {
     a: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
     b: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 fn main() {
diff --git a/gcc/testsuite/rust/compile/torture/struct_init_7.rs b/gcc/testsuite/rust/compile/torture/struct_init_7.rs
index a8c8050..a73d642 100644
--- a/gcc/testsuite/rust/compile/torture/struct_init_7.rs
+++ b/gcc/testsuite/rust/compile/torture/struct_init_7.rs
@@ -1,6 +1,8 @@
 struct Foo {
     a: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
     b: f32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 fn main() {
diff --git a/gcc/testsuite/rust/compile/torture/type_infer1.rs b/gcc/testsuite/rust/compile/torture/type_infer1.rs
index b6502b5..3fee728 100644
--- a/gcc/testsuite/rust/compile/torture/type_infer1.rs
+++ b/gcc/testsuite/rust/compile/torture/type_infer1.rs
@@ -1,6 +1,8 @@
 struct Foo {
     one: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
     two: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 fn test(x: i32) -> i32 {
diff --git a/gcc/testsuite/rust/compile/torture/type_infer5.rs b/gcc/testsuite/rust/compile/torture/type_infer5.rs
index 1bccb4c..2c2602a 100644
--- a/gcc/testsuite/rust/compile/torture/type_infer5.rs
+++ b/gcc/testsuite/rust/compile/torture/type_infer5.rs
@@ -1,6 +1,7 @@
 struct Foo {
     a: i32,
     b: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
 }
 
 fn main() {
diff --git a/gcc/testsuite/rust/compile/torture/unused_struct_field.rs b/gcc/testsuite/rust/compile/torture/unused_struct_field.rs
new file mode 100644
index 0000000..429b303
--- /dev/null
+++ b/gcc/testsuite/rust/compile/torture/unused_struct_field.rs
@@ -0,0 +1,9 @@
+struct Foo {
+    one: i32,
+// { dg-warning "field is never read" "" { target *-*-* } .-1 }
+    two: i32
+}
+fn main() {
+    let _a = Foo {one: 1, two: 2};
+    let _b = _a.two;
+}
\ No newline at end of file