re PR c++/38908 (Unexplained "'<anonymous>' is used uninitialized in this function...

        PR c++/38908
        * class.c (is_really_empty_class): New fn.
        * cp-tree.h: Declare it.
        * cp-objcp-common.c (cp_expr_size): Use it.

From-SVN: r144643

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 187ade4067815a22b2223d309c98b53644fe99e6..31a626bc1ade710344b879261415e2f3675e348a 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,10 @@
 2009-03-04  Jason Merrill  <jason@redhat.com>
 
+       PR c++/38908
+       * class.c (is_really_empty_class): New fn.
+       * cp-tree.h: Declare it.
+       * cp-objcp-common.c (cp_expr_size): Use it.
+
        PR c++/13549
        * semantics.c (perform_koenig_lookup): Handle TEMPLATE_ID_EXPR.
        * parser.c (cp_parser_postfix_expression): Call it for 

diff --git a/gcc/cp/class.c b/gcc/cp/class.c
index ae89218a700d0a5001c9de2a2f0df3bace65241a..b8553effc03a4900a8c8d8c2e97089ecafd79f17 100644 (file)
--- a/gcc/cp/class.c
+++ b/gcc/cp/class.c
@@ -6461,7 +6461,7 @@ is_empty_class (tree type)
   if (type == error_mark_node)
     return 0;
 
-  if (! MAYBE_CLASS_TYPE_P (type))
+  if (! CLASS_TYPE_P (type))
     return 0;
 
   /* In G++ 3.2, whether or not a class was empty was determined by
@@ -6501,6 +6501,37 @@ contains_empty_class_p (tree type)
   return false;
 }
 
+/* Returns true if TYPE contains no actual data, just various
+   possible combinations of empty classes.  */
+
+bool
+is_really_empty_class (tree type)
+{
+  if (is_empty_class (type))
+    return true;
+  if (CLASS_TYPE_P (type))
+    {
+      tree field;
+      tree binfo;
+      tree base_binfo;
+      int i;
+
+      for (binfo = TYPE_BINFO (type), i = 0;
+          BINFO_BASE_ITERATE (binfo, i, base_binfo); ++i)
+       if (!is_really_empty_class (BINFO_TYPE (base_binfo)))
+         return false;
+      for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
+       if (TREE_CODE (field) == FIELD_DECL
+           && !DECL_ARTIFICIAL (field)
+           && !is_really_empty_class (TREE_TYPE (field)))
+         return false;
+      return true;
+    }
+  else if (TREE_CODE (type) == ARRAY_TYPE)
+    return is_really_empty_class (TREE_TYPE (type));
+  return false;
+}
+
 /* Note that NAME was looked up while the current class was being
    defined and that the result of that lookup was DECL.  */
 

diff --git a/gcc/cp/cp-objcp-common.c b/gcc/cp/cp-objcp-common.c
index 7d2e870bc80c4ca96d0e9f4923bcc5ef1678e320..fefafb1ac7ea9390a6092edd0e63ef0d38526e75 100644 (file)
--- a/gcc/cp/cp-objcp-common.c
+++ b/gcc/cp/cp-objcp-common.c
@@ -101,7 +101,7 @@ cp_expr_size (const_tree exp)
             constructed, this is a valid transformation.  */
          || CP_AGGREGATE_TYPE_P (type))
        /* This would be wrong for a type with virtual bases.  */
-       return (is_empty_class (type)
+       return (is_really_empty_class (type)
                ? size_zero_node
                : CLASSTYPE_SIZE_UNIT (type));
       else

diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index b6bf7d40da0939c5ff87ddc4b4afdd0d4fe5ed37..aedf5b96749b44388b3dec2728a09f7c6c2e96c2 100644 (file)
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -4240,6 +4240,7 @@ extern void finish_struct_1                       (tree);
 extern int resolves_to_fixed_type_p            (tree, int *);
 extern void init_class_processing              (void);
 extern int is_empty_class                      (tree);
+extern bool is_really_empty_class              (tree);
 extern void pushclass                          (tree);
 extern void popclass                           (void);
 extern void push_nested_class                  (tree);

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f71de1c30e9b7ad46166c611efc091642ed89407..37c4074dc87374238cbb4cb57cd284135e3da852 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2009-03-05  Jason Merrill  <jason@redhat.com>
+
+       PR c++/38908
+       * g++.dg/warn/Wuninitialized-3.C: New test.
+
 2009-03-05  Jakub Jelinek  <jakub@redhat.com>
 
        PR debug/39379

diff --git a/gcc/testsuite/g++.dg/warn/Wuninitialized-3.C b/gcc/testsuite/g++.dg/warn/Wuninitialized-3.C
new file mode 100644 (file)
index 0000000..dc3be3f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wuninitialized-3.C
@@ -0,0 +1,17 @@
+// PR C++/38908
+// { dg-options "-Wuninitialized -O" }
+
+struct empty {};
+
+struct dfs_visitor {
+    dfs_visitor() { }
+    empty m_vis;
+};
+
+void bar(const dfs_visitor&);
+void foo(void)
+{
+  dfs_visitor vis;
+  dfs_visitor vis2 = vis;
+  bar (vis2);
+}