c++: -Woverloaded-virtual false positive [PR87729]

My attempt to shortcut unnecessary checking after finding a match was
also wrong for multiple inheritance, so let's give up on it.

	PR c++/87729

gcc/cp/ChangeLog:

	* class.cc (warn_hidden): Remove shortcut.

gcc/testsuite/ChangeLog:

	* g++.dg/warn/Woverloaded-virt4.C: New test.

diff --git a/gcc/cp/class.cc b/gcc/cp/class.cc
index eb69e7f985cc84c834dd4bbb302cf2782b97ca25..a12d3673b961dba2a8bc56df6eb3efded0862404 100644 (file)
--- a/gcc/cp/class.cc
+++ b/gcc/cp/class.cc
@@ -3040,22 +3040,25 @@ warn_hidden (tree t)
        bool seen_non_override = false;
        for (tree fndecl : ovl_range (fns))
          {
+           bool any_override = false;
            if (TREE_CODE (fndecl) == FUNCTION_DECL
                && DECL_VINDEX (fndecl))
              {
                /* If the method from the base class has the same
                   signature as the method from the derived class, it
-                  has been overridden.  */
+                  has been overridden.  Note that we can't move on
+                  after finding one match: fndecl might override
+                  multiple base fns.  */
                for (size_t k = 0; k < base_fndecls.length (); k++)
                  if (base_fndecls[k]
                      && same_signature_p (fndecl, base_fndecls[k]))
                    {
                      base_fndecls[k] = NULL_TREE;
-                     goto next;
+                     any_override = true;
                    }
              }
-           seen_non_override = true;
-         next:;
+           if (!any_override)
+             seen_non_override = true;
          }
 
        if (!seen_non_override && warn_overloaded_virtual == 1)

diff --git a/gcc/testsuite/g++.dg/warn/Woverloaded-virt4.C b/gcc/testsuite/g++.dg/warn/Woverloaded-virt4.C
new file mode 100644 (file)
index 0000000..b4d8668
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Woverloaded-virt4.C
@@ -0,0 +1,7 @@
+// PR c++/87729
+// { dg-additional-options -Woverloaded-virtual }
+
+struct S1 { virtual void f(); };
+struct S2: S1 {};
+struct S3: S1 {};
+struct S4: S2, S3 { void f(); };