From 3072125a40ccfc139a92d44fb3911a8a7186b025 Mon Sep 17 00:00:00 2001
From: Martin Sebor <msebor@redhat.com>
Date: Mon, 16 Nov 2020 20:01:10 -0700
Subject: [PATCH] PR middle-end/97840 - Bogus -Wmaybe-uninitialized passing an
 empty object to a function

gcc/ChangeLog:
	* tree-ssa-uninit.c (maybe_warn_operand): Call is_empty_type.
	* tree.c (default_is_empty_type): Rename...
	(is_empty_type): ...to this.
	* tree.h (is_empty_type): Declare.
---
 gcc/tree-ssa-uninit.c |  5 +----
 gcc/tree.c            | 10 +++++-----
 gcc/tree.h            |  1 +
 3 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/gcc/tree-ssa-uninit.c b/gcc/tree-ssa-uninit.c
index c94831bfb75..516a7bd2c99 100644
--- a/gcc/tree-ssa-uninit.c
+++ b/gcc/tree-ssa-uninit.c
@@ -404,10 +404,7 @@ maybe_warn_operand (ao_ref &ref, gimple *stmt, tree lhs, tree rhs,
   tree rhstype = TREE_TYPE (rhs);
   if (POINTER_TYPE_P (rhstype))
     rhstype = TREE_TYPE (rhstype);
-  if (TYPE_EMPTY_P (rhstype)
-      || (RECORD_OR_UNION_TYPE_P (rhstype)
-	  && (!first_field (rhstype)
-	      || default_is_empty_record (rhstype))))
+  if (is_empty_type (rhstype))
     return NULL_TREE;
 
   bool warned = false;
diff --git a/gcc/tree.c b/gcc/tree.c
index 1ad4ad5a5f7..0fe9097bbbc 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -15136,22 +15136,22 @@ get_nonnull_args (const_tree fntype)
 /* Returns true if TYPE is a type where it and all of its subobjects
    (recursively) are of structure, union, or array type.  */
 
-static bool
-default_is_empty_type (tree type)
+bool
+is_empty_type (const_tree type)
 {
   if (RECORD_OR_UNION_TYPE_P (type))
     {
       for (tree field = TYPE_FIELDS (type); field; field = DECL_CHAIN (field))
 	if (TREE_CODE (field) == FIELD_DECL
 	    && !DECL_PADDING_P (field)
-	    && !default_is_empty_type (TREE_TYPE (field)))
+	    && !is_empty_type (TREE_TYPE (field)))
 	  return false;
       return true;
     }
   else if (TREE_CODE (type) == ARRAY_TYPE)
     return (integer_minus_onep (array_type_nelts (type))
 	    || TYPE_DOMAIN (type) == NULL_TREE
-	    || default_is_empty_type (TREE_TYPE (type)));
+	    || is_empty_type (TREE_TYPE (type)));
   return false;
 }
 
@@ -15170,7 +15170,7 @@ default_is_empty_record (const_tree type)
   if (TREE_ADDRESSABLE (type))
     return false;
 
-  return default_is_empty_type (TYPE_MAIN_VARIANT (type));
+  return is_empty_type (TYPE_MAIN_VARIANT (type));
 }
 
 /* Determine whether TYPE is a structure with a flexible array member,
diff --git a/gcc/tree.h b/gcc/tree.h
index 9a713cdb0c7..5c0e3cc2e5a 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -6233,6 +6233,7 @@ extern void gt_pch_nx (tree &);
 extern void gt_pch_nx (tree &, gt_pointer_operator, void *);
 
 extern bool nonnull_arg_p (const_tree);
+extern bool is_empty_type (const_tree);
 extern bool default_is_empty_record (const_tree);
 extern bool flexible_array_type_p (const_tree);
 extern HOST_WIDE_INT arg_int_size_in_bytes (const_tree);
-- 
2.30.2