PR c++/86485 - simple_empty_class_p
Yet another tweak that would have fixed this bug: we should treat INIT_EXPR
and MODIFY_EXPR differently for determining whether this is a simple empty
class copy, since a TARGET_EXPR on the RHS is direct initialization if
INIT_EXPR but copy if MODIFY_EXPR.
* cp-gimplify.c (simple_empty_class_p): Also true for MODIFY_EXPR.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@271521 138bc75d-0d04-0410-961f-82ee72b054a4
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 970f7e8..6c98696 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2019-05-22 Jason Merrill <jason@redhat.com>
+
+ PR c++/86485 - -Wmaybe-unused with empty class ?:
+ * cp-gimplify.c (simple_empty_class_p): Also true for MODIFY_EXPR.
+
2019-05-21 Paolo Carlini <paolo.carlini@oracle.com>
* parser.c (cp_parser_template_declaration_after_parameters): Use
diff --git a/gcc/cp/cp-gimplify.c b/gcc/cp/cp-gimplify.c
index e8c22c0..30937b1 100644
--- a/gcc/cp/cp-gimplify.c
+++ b/gcc/cp/cp-gimplify.c
@@ -594,19 +594,20 @@
return slot optimization alone because it isn't a copy. */
static bool
-simple_empty_class_p (tree type, tree op)
+simple_empty_class_p (tree type, tree op, tree_code code)
{
+ if (TREE_CODE (op) == COMPOUND_EXPR)
+ return simple_empty_class_p (type, TREE_OPERAND (op, 1), code);
return
- ((TREE_CODE (op) == COMPOUND_EXPR
- && simple_empty_class_p (type, TREE_OPERAND (op, 1)))
- || TREE_CODE (op) == EMPTY_CLASS_EXPR
+ (TREE_CODE (op) == EMPTY_CLASS_EXPR
+ || code == MODIFY_EXPR
|| is_gimple_lvalue (op)
|| INDIRECT_REF_P (op)
|| (TREE_CODE (op) == CONSTRUCTOR
- && CONSTRUCTOR_NELTS (op) == 0
- && !TREE_CLOBBER_P (op))
+ && CONSTRUCTOR_NELTS (op) == 0)
|| (TREE_CODE (op) == CALL_EXPR
&& !CALL_EXPR_RETURN_SLOT_OPT (op)))
+ && !TREE_CLOBBER_P (op)
&& is_really_empty_class (type, /*ignore_vptr*/true);
}
@@ -715,7 +716,7 @@
TREE_OPERAND (*expr_p, 1) = build1 (VIEW_CONVERT_EXPR,
TREE_TYPE (op0), op1);
- else if (simple_empty_class_p (TREE_TYPE (op0), op1))
+ else if (simple_empty_class_p (TREE_TYPE (op0), op1, code))
{
/* Remove any copies of empty classes. Also drop volatile
variables on the RHS to avoid infinite recursion from