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

[Jason Merrill <jason@redhat.com>]

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

Tested x86_64-pc-linux-gnu, applying to trunk.

	PR c++/87729

gcc/cp/ChangeLog:

	* class.cc (warn_hidden): Remove shortcut.

gcc/testsuite/ChangeLog:

	* g++.dg/warn/Woverloaded-virt4.C: New test.
---
 gcc/cp/class.cc                               | 11 +++++++----
 gcc/testsuite/g++.dg/warn/Woverloaded-virt4.C |  7 +++++++
 2 files changed, 14 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/warn/Woverloaded-virt4.C

diff --git a/gcc/cp/class.cc b/gcc/cp/class.cc
index eb69e7f985c..a12d3673b96 100644
--- 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
index 00000000000..b4d86689cf5
--- /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(); };

base-commit: 718cf8d0bd32689192200d2156722167fd21a647
-- 
2.31.1