[C++ patch] Reject virt-specifiers on friends and member templates

[Ville Voutilainen]

On 12 August 2014 11:47, Ville Voutilainen <ville.voutilainen@gmail.com> wrote:
> We shouldn't allow friend declarations and member templates to
> have virt-specifiers, as neither of those can be virtual. Tested on
> Linux x86-64.
> Note that the standardese can be squinted at in a way that would allow
> virt-specifiers on friends, there's a DR coming for that. I do not expect
> the resolution of that DR to be anything but banning virt-specifiers
> on such declarations. Clang has very recently made a similar fix for
> friend declarations, and it already rejected virt-specifiers on member
> templates.

Minor tweak to the diagnostic for friends, say "friend declaration" instead
of "member declared as a friend". Changelog unchanged, attached for
convenience.
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diff --git a/gcc/cp/friend.c b/gcc/cp/friend.c
index a30918c..9b37d86 100644
--- a/gcc/cp/friend.c
+++ b/gcc/cp/friend.c
@@ -426,6 +426,10 @@ do_friend (tree ctype, tree declarator, tree decl,
 
   /* Every decl that gets here is a friend of something.  */
   DECL_FRIEND_P (decl) = 1;
+  
+  if (DECL_OVERRIDE_P (decl) || DECL_FINAL_P (decl))
+    error ("friend declaration %qD may not have virt-specifiers",
+	   decl);
 
   /* Unfortunately, we have to handle attributes here.  Normally we would
      handle them in start_decl_1, but since this is a friend decl start_decl_1
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 2592172..90b2720 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -4737,6 +4737,11 @@ push_template_decl_real (tree decl, bool is_friend)
 	}
       else if (TREE_CODE (decl) == FUNCTION_DECL)
 	{
+	  if (member_template_p)
+	    {
+	      if (DECL_OVERRIDE_P (decl) || DECL_FINAL_P (decl))
+		error ("member template %qD may not have virt-specifiers", decl);
+	    }
 	  if (DECL_DESTRUCTOR_P (decl))
 	    {
 	      /* [temp.mem]
diff --git a/gcc/testsuite/g++.dg/cpp0x/override1.C b/gcc/testsuite/g++.dg/cpp0x/override1.C
index f5f00ee..05d7290 100644
--- a/gcc/testsuite/g++.dg/cpp0x/override1.C
+++ b/gcc/testsuite/g++.dg/cpp0x/override1.C
@@ -52,6 +52,14 @@ struct D5 : B
 void D5::g() override {} // { dg-error "not allowed outside a class definition" }
 void g() override {} // { dg-error "not allowed outside a class definition" }
 
+struct B5
+{
+  friend void f() final; // { dg-error "may not have virt-specifiers" }
+  friend void g() override; // { dg-error "may not have virt-specifiers" }
+  template <class T> void h() final; // { dg-error "may not have virt-specifiers" }
+  template <class T> void i() override; // { dg-error "may not have virt-specifiers" }
+};
+
 int main()
 {
   D2<B> d;
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