Revert "c++: Fix overeager Woverloaded-virtual with conversion operators [PR109918]"

This reverts commit 60163c8573.

gcc/cp/class.cc

@@ -3243,15 +3243,10 @@ warn_hidden (tree t)
 	  continue;
 
 	tree name = OVL_NAME (fns);
-	size_t num_fns = 0; /* The number of fndecls in fns.  */
 	auto_vec<tree, 20> base_fndecls;
 	tree base_binfo;
 	tree binfo;
 	unsigned j;
-	hash_set<tree> overriden_base_fndecls;
-	/* base_fndecls that are hidden but not overriden. The "value"
-	   contains the fndecl that hides the "key".  */
-	hash_map<tree, tree> hidden_base_fndecls;
 
 	if (IDENTIFIER_CDTOR_P (name))
 	  continue;
@@ -3269,63 +3264,47 @@ warn_hidden (tree t)
 	if (base_fndecls.is_empty ())
 	  continue;
 
-	/* Find all the base_fndecls that are overridden, as well as those
-	   that are hidden, in T.  */
+	/* Remove any overridden functions.  */
+	bool seen_non_override = false;
 	for (tree fndecl : ovl_range (fns))
 	  {
-	    fndecl = STRIP_TEMPLATE (fndecl);
+	    bool any_override = false;
 	    if (TREE_CODE (fndecl) == FUNCTION_DECL
-		&& fndecl != conv_op_marker)
+		&& DECL_VINDEX (fndecl))
 	      {
-		num_fns++;
-		tree fndecl_vindex = DECL_VINDEX (fndecl);
-		/* If the method from the base class has the same DECL_VINDEX
-		   as the method from the derived, it has been overridden.
-		   Note that we can't move on after finding one match: fndecl
-		   might override multiple base fns.  */
+		/* If the method from the base class has the same
+		   signature as the method from the derived class, it
+		   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] || !DECL_VINDEX (base_fndecls[k]))
-		      continue;
-		    tree base_fndecl_vindex = DECL_VINDEX (base_fndecls[k]);
-		    if (fndecl_vindex
-			&& !tree_int_cst_compare (fndecl_vindex,
-						  base_fndecl_vindex))
-		      overriden_base_fndecls.add (base_fndecls[k]);
-		    else if (IDENTIFIER_CONV_OP_P (name)
-			     && (DECL_NAME (fndecl)
-				 != DECL_NAME (base_fndecls[k])))
-		      /* If base_fndecl[k] and fndecl are conversion operators
-			 to different types, they're unrelated.  */
-		      ;
-		    else
-		      hidden_base_fndecls.put (base_fndecls[k], fndecl);
-		  }
+		  if (base_fndecls[k]
+		      && same_signature_p (fndecl, base_fndecls[k]))
+		    {
+		      base_fndecls[k] = NULL_TREE;
+		      any_override = true;
+		    }
 	      }
+	    if (!any_override)
+	      seen_non_override = true;
 	  }
 
-	if (warn_overloaded_virtual == 1
-	    && overriden_base_fndecls.elements () == num_fns)
-	  /* All the fns override a base virtual.  */
-	  continue;
+	if (!seen_non_override && warn_overloaded_virtual == 1)
+	  /* All the derived fns override base virtuals.  */
+	  return;
 
-	/* Now give a warning for all hidden methods. Note that a method that
-	   is both in hidden_base_fndecls and overriden_base_fndecls is not
-	   hidden.  */
-	for (auto hidden_base_fndecl : hidden_base_fndecls)
-	  {
-	    tree hidden_fndecl = hidden_base_fndecl.first;
-	    tree hider = hidden_base_fndecl.second;
-	    if (!hidden_fndecl
-		|| overriden_base_fndecls.contains (hidden_fndecl))
-	      continue;
-	    gcc_assert (hider);
-	    auto_diagnostic_group d;
-	    if (warning_at (location_of (hidden_fndecl),
-			    OPT_Woverloaded_virtual_,
-			    "%qD was hidden", hidden_fndecl))
-	      inform (location_of (hider), "  by %qD", hider);
-	  }
+	/* Now give a warning for all base functions without overriders,
+	   as they are hidden.  */
+	for (tree base_fndecl : base_fndecls)
+	  if (base_fndecl)
+	    {
+	      auto_diagnostic_group d;
+	      /* Here we know it is a hider, and no overrider exists.  */
+	      if (warning_at (location_of (base_fndecl),
+			      OPT_Woverloaded_virtual_,
+			      "%qD was hidden", base_fndecl))
+		inform (location_of (fns), "  by %qD", fns);
+	    }
       }
 }
 

gcc/cp/error.cc

@@ -3397,8 +3397,7 @@ location_of (tree t)
 	return input_location;
     }
   else if (TREE_CODE (t) == OVERLOAD)
-    t = OVL_FIRST (t) != conv_op_marker ? OVL_FIRST (t)
-      : OVL_FIRST (OVL_CHAIN (t));
+    t = OVL_FIRST (t);
 
   if (DECL_P (t))
     return DECL_SOURCE_LOCATION (t);

gcc/testsuite/g++.dg/warn/Woverloaded-virt1.C

@@ -5,12 +5,10 @@ class Foo
 {
 public:
     virtual void f(int);	// { dg-warning "hidden" }
-    void g(int);		// Not virtual, so no warning
 };
 
 class Bar : public Foo
 {
 public:
     virtual void f(short);	// { dg-message "by" }
-    virtual void g(short);
 };

gcc/testsuite/g++.dg/warn/Woverloaded-virt5.C

@@ -1,12 +0,0 @@
-// PR c++/109918 - Exact PR testcase
-// { dg-do compile }
-// { dg-additional-options -Wall }
-
-struct A {
-  virtual operator int() { return 42; }
-  virtual operator char() = 0;
-};
-
-struct B : public A {
-  operator char() { return 'A'; }
-};

gcc/testsuite/g++.dg/warn/Woverloaded-virt6.C

@@ -1,12 +0,0 @@
-// PR c++/109918 - PR testcase with -Woverloaded-virtual=2
-// { dg-do compile }
-// { dg-additional-options -Woverloaded-virtual=2 }
-
-struct A {
-  virtual operator int() { return 42; }
-  virtual operator char() = 0;
-};
-
-struct B : public A {
-  operator char() { return 'A'; }
-};

gcc/testsuite/g++.dg/warn/Woverloaded-virt7.C

@@ -1,25 +0,0 @@
-// PR c++/109918 - Test different CV-quals
-// { dg-do compile }
-// { dg-additional-options -Woverloaded-virtual }
-
-struct A {
-  virtual operator char() { return 'a'; }
-  virtual operator char() const { return 'b'; } // { dg-warning "was hidden" }
-  virtual operator int() { return 42; }
-};
-
-struct B : public A {
-  operator char() { return 'A'; } // { dg-note "by" }
-  operator int() { return 43; }
-};
-
-struct AA {
-  virtual char func(char) { return 'a'; }
-  virtual char func(char) const { return 'b'; } // { dg-warning "was hidden" }
-  virtual int func(int) { return 42; }
-};
-
-struct BB : public AA {
-  char func(char) { return 'A'; } // { dg-note "by" }
-  int func(int) { return 43; }
-};

gcc/testsuite/g++.dg/warn/Woverloaded-virt8.C

@@ -1,15 +0,0 @@
-// Identified when investigating PR c++/109918: no warning was emitted due to
-// an incorrect early return in warn_hidden.
-// { dg-additional-options -Wall }
-
-struct Foo
-{
-  virtual void f(int); // { dg-warning "hidden" }
-  virtual void g() {}
-};
-
-struct Bar : Foo
-{
-  virtual void f(short); // { dg-message "by" }
-  virtual void g() {}
-};

gcc/testsuite/g++.dg/warn/Woverloaded-virt9.C

@@ -1,14 +0,0 @@
-// PR c++/109918: Non virtual overloads in derived classes that don't override
-// anything shouldn't cause warnings, even at -Woverloaded-virtual=2
-// { dg-additional-options -Woverloaded-virtual=2 }
-
-struct Foo
-{
-  virtual void g() {}
-};
-
-struct Bar : Foo
-{
-  virtual void g() {}
-  void g(int) {}
-};