Merge branch 'master' into devel/sphinx

3 files changed, 48 insertions, 3 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index ed83b97..f1c96b4 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,15 @@
+2022-08-15  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/106276
+	* typeck.cc (can_do_rvo_p): New.
+	(maybe_warn_pessimizing_move): Warn when moving a temporary object
+	in a return statement prevents copy elision.
+
+2022-08-11  Marek Polacek  <polacek@redhat.com>
+
+	PR middle-end/102633
+	* decl.cc (cp_finish_decl): Call suppress_warning.
+
 2022-08-07  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/88174
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 70ad681..ff56fdd 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -8253,6 +8253,14 @@ cp_finish_decl (tree decl, tree init, bool init_const_expr_p,
 	      && !TYPE_REF_P (type))
 	    TREE_CONSTANT (decl) = 1;
 	}
+      /* This is handled mostly by gimplify.cc, but we have to deal with
+	 not warning about int x = x; as it is a GCC extension to turn off
+	 this warning but only if warn_init_self is zero.  */
+      if (!DECL_EXTERNAL (decl)
+	  && !TREE_STATIC (decl)
+	  && decl == tree_strip_any_location_wrapper (init)
+	  && !warn_init_self)
+	suppress_warning (decl, OPT_Winit_self);
     }
 
   if (flag_openmp
diff --git a/gcc/cp/typeck.cc b/gcc/cp/typeck.cc
index 6e4f23a..15548e5 100644
--- a/gcc/cp/typeck.cc
+++ b/gcc/cp/typeck.cc
@@ -10287,12 +10287,29 @@ can_do_nrvo_p (tree retval, tree functype)
 	  /* The cv-unqualified type of the returned value must be the
 	     same as the cv-unqualified return type of the
 	     function.  */
-	  && same_type_p ((TYPE_MAIN_VARIANT (TREE_TYPE (retval))),
-			  (TYPE_MAIN_VARIANT (functype)))
+	  && same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (retval)),
+			  TYPE_MAIN_VARIANT (functype))
 	  /* And the returned value must be non-volatile.  */
 	  && !TYPE_VOLATILE (TREE_TYPE (retval)));
 }
 
+/* Like can_do_nrvo_p, but we check if we're trying to move a class
+   prvalue.  */
+
+static bool
+can_do_rvo_p (tree retval, tree functype)
+{
+  if (functype == error_mark_node)
+    return false;
+  if (retval)
+    STRIP_ANY_LOCATION_WRAPPER (retval);
+  return (retval != NULL_TREE
+	  && !glvalue_p (retval)
+	  && same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (retval)),
+			  TYPE_MAIN_VARIANT (functype))
+	  && !TYPE_VOLATILE (TREE_TYPE (retval)));
+}
+
 /* If we should treat RETVAL, an expression being returned, as if it were
    designated by an rvalue, returns it adjusted accordingly; otherwise, returns
    NULL_TREE.  See [class.copy.elision].  RETURN_P is true if this is a return
@@ -10401,12 +10418,20 @@ maybe_warn_pessimizing_move (tree retval, tree functype)
 			      "prevents copy elision"))
 		inform (loc, "remove %<std::move%> call");
 	    }
+	  else if (can_do_rvo_p (arg, functype))
+	    {
+	      auto_diagnostic_group d;
+	      if (warning_at (loc, OPT_Wpessimizing_move,
+			      "moving a temporary object in a return statement "
+			      "prevents copy elision"))
+		inform (loc, "remove %<std::move%> call");
+	    }
 	  /* Warn if the move is redundant.  It is redundant when we would
 	     do maybe-rvalue overload resolution even without std::move.  */
 	  else if (warn_redundant_move
 		   && (moved = treat_lvalue_as_rvalue_p (arg, /*return*/true)))
 	    {
-	      /* Make sure that the overload resolution would actually succeed
+	      /* Make sure that overload resolution would actually succeed
 		 if we removed the std::move call.  */
 	      tree t = convert_for_initialization (NULL_TREE, functype,
 						   moved,