Hi,
the below resolves the bug report and its duplicates by implementing -
in a rather straightforward way, I believe - the resolution of DR 136,
which also made into C++17. Note that in the patch I used permerror
instead of a plain error for consistency with the other check
(check_redeclaration_no_default_args) which I added (rather) recently,
and I'm exploiting that to allow two existing testcases to compile as
they are. Tested x86_64-linux.
Thanks, Paolo.
/////////////////
/cp
2019-07-12 Paolo Carlini <paolo.carl...@oracle.com>
PR c++/59480, DR 136
* decl.c (check_no_redeclaration_friend_default_args): New.
(duplicate_decls): Use the latter; also check that a friend
declaration specifying default arguments is a definition.
/testsuite
2019-07-12 Paolo Carlini <paolo.carl...@oracle.com>
PR c++/59480, DR 136
* g++.dg/other/friend8.C: New.
* g++.dg/other/friend9.C: Likewise.
* g++.dg/other/friend10.C: Likewise.
* g++.dg/other/friend11.C: Likewise.
* g++.dg/other/friend12.C: Likewise.
* g++.dg/parse/defarg4.C: Compile with -fpermissive -w.
* g++.dg/parse/defarg8.C: Likewise.
Index: cp/decl.c
===================================================================
--- cp/decl.c (revision 262577)
+++ cp/decl.c (working copy)
@@ -1280,6 +1280,39 @@ check_redeclaration_no_default_args (tree decl)
}
}
+/* NEWDECL is a redeclaration of a function or function template OLDDECL.
+ If either the declaration or the redeclaration is a friend declaration
+ and specifies default arguments issue a diagnostic. Note: this is to
+ enforce C++17 11.3.6/4: "If a friend declaration specifies a default
+ argument expression, that declaration... shall be the only declaration
+ of the function or function template in the translation unit." */
+
+static void
+check_no_redeclaration_friend_default_args (tree olddecl, tree newdecl)
+{
+ bool olddecl_friend_p = DECL_FRIEND_P (STRIP_TEMPLATE (olddecl));
+ bool newdecl_friend_p = DECL_FRIEND_P (STRIP_TEMPLATE (newdecl));
+
+ if (!olddecl_friend_p && !newdecl_friend_p)
+ return;
+
+ tree t1 = FUNCTION_FIRST_USER_PARMTYPE (olddecl);
+ tree t2 = FUNCTION_FIRST_USER_PARMTYPE (newdecl);
+
+ for (; t1 && t1 != void_list_node;
+ t1 = TREE_CHAIN (t1), t2 = TREE_CHAIN (t2))
+ if ((olddecl_friend_p && TREE_PURPOSE (t1))
+ || (newdecl_friend_p && TREE_PURPOSE (t2)))
+ {
+ if (permerror (DECL_SOURCE_LOCATION (newdecl),
+ "friend declaration of %q#D specifies default "
+ "arguments and isn't the only declaration", newdecl))
+ inform (DECL_SOURCE_LOCATION (olddecl),
+ "previous declaration of %q#D", olddecl);
+ return;
+ }
+}
+
/* Merge tree bits that correspond to attributes noreturn, nothrow,
const, malloc, and pure from NEWDECL with those of OLDDECL. */
@@ -1876,6 +1909,12 @@ next_arg:;
olddecl);
}
}
+
+ /* C++17 11.3.6/4: "If a friend declaration specifies a default
+ argument expression, that declaration... shall be the only
+ declaration of the function or function template in the
+ translation unit." */
+ check_no_redeclaration_friend_default_args (olddecl, newdecl);
}
}
}
@@ -2008,11 +2047,18 @@ next_arg:;
if (DECL_FUNCTION_TEMPLATE_P (newdecl))
{
- /* Per C++11 8.3.6/4, default arguments cannot be added in later
- declarations of a function template. */
if (DECL_SOURCE_LOCATION (newdecl)
!= DECL_SOURCE_LOCATION (olddecl))
- check_redeclaration_no_default_args (newdecl);
+ {
+ /* Per C++11 8.3.6/4, default arguments cannot be added in
+ later declarations of a function template. */
+ check_redeclaration_no_default_args (newdecl);
+ /* C++17 11.3.6/4: "If a friend declaration specifies a default
+ argument expression, that declaration... shall be the only
+ declaration of the function or function template in the
+ translation unit." */
+ check_no_redeclaration_friend_default_args (olddecl, newdecl);
+ }
check_default_args (newdecl);
@@ -8742,6 +8788,18 @@ grokfndecl (tree ctype,
}
}
+ /* C++17 11.3.6/4: "If a friend declaration specifies a default argument
+ expression, that declaration shall be a definition..." */
+ if (friendp && !funcdef_flag)
+ {
+ for (tree t = FUNCTION_FIRST_USER_PARMTYPE (decl);
+ t && t != void_list_node; t = TREE_CHAIN (t))
+ if (TREE_PURPOSE (t))
+ permerror (DECL_SOURCE_LOCATION (decl),
+ "friend declaration of %qD specifies default "
+ "arguments and isn't a definition", decl);
+ }
+
/* If this decl has namespace scope, set that up. */
if (in_namespace)
set_decl_namespace (decl, in_namespace, friendp);
Index: testsuite/g++.dg/other/friend10.C
===================================================================
--- testsuite/g++.dg/other/friend10.C (nonexistent)
+++ testsuite/g++.dg/other/friend10.C (working copy)
@@ -0,0 +1,9 @@
+// PR c++/59480
+
+class test {
+ friend int foo(bool = true) { return 1; } // { dg-message "14:previous" }
+ template<typename> friend int bar(bool = true) { return 1; } // {
dg-message "33:previous" }
+};
+
+int foo(bool); // { dg-error "5:friend declaration" }
+template<typename> int bar(bool); // { dg-error "24:friend declaration" }
Index: testsuite/g++.dg/other/friend11.C
===================================================================
--- testsuite/g++.dg/other/friend11.C (nonexistent)
+++ testsuite/g++.dg/other/friend11.C (working copy)
@@ -0,0 +1,8 @@
+// PR c++/59480
+
+class test {
+ friend int foo(bool = true) { return 1; } // { dg-message "14:previous" }
+ friend int foo(bool); // { dg-error "14:friend declaration" }
+ template<typename> friend int bar(bool = true) { return 1; } // {
dg-message "33:previous" }
+ template<typename> friend int bar(bool); // { dg-error "33:friend
declaration" }
+};
Index: testsuite/g++.dg/other/friend12.C
===================================================================
--- testsuite/g++.dg/other/friend12.C (nonexistent)
+++ testsuite/g++.dg/other/friend12.C (working copy)
@@ -0,0 +1,11 @@
+// PR c++/59480
+
+template<typename>
+class test {
+ friend int foo(bool = true) { return 1; } // { dg-message "14:previous" }
+ friend int foo(bool); // { dg-error "14:friend declaration" }
+ template<typename> friend int bar(bool = true) { return 1; } // {
dg-message "33:previous" }
+ template<typename> friend int bar(bool); // { dg-error "33:friend
declaration" }
+};
+
+template class test<bool>;
Index: testsuite/g++.dg/other/friend8.C
===================================================================
--- testsuite/g++.dg/other/friend8.C (nonexistent)
+++ testsuite/g++.dg/other/friend8.C (working copy)
@@ -0,0 +1,6 @@
+// PR c++/59480
+
+class test {
+ friend int foo(bool = true); // { dg-error "14:friend declaration" }
+ template<typename> friend int bar(bool = true); // { dg-error "33:friend
declaration" }
+};
Index: testsuite/g++.dg/other/friend9.C
===================================================================
--- testsuite/g++.dg/other/friend9.C (nonexistent)
+++ testsuite/g++.dg/other/friend9.C (working copy)
@@ -0,0 +1,9 @@
+// PR c++/59480
+
+template<typename>
+class test {
+ friend int foo(bool = true); // { dg-error "14:friend declaration" }
+ template<typename> friend int bar(bool = true); // { dg-error "33:friend
declaration" }
+};
+
+template class test<bool>;
Index: testsuite/g++.dg/parse/defarg4.C
===================================================================
--- testsuite/g++.dg/parse/defarg4.C (revision 262577)
+++ testsuite/g++.dg/parse/defarg4.C (working copy)
@@ -1,4 +1,4 @@
-// { dg-do compile }
+// { dg-options "-fpermissive -w" }
// Copyright (C) 2003 Free Software Foundation, Inc.
// Contributed by Nathan Sidwell 3 Jul 2003 <nat...@codesourcery.com>
Index: testsuite/g++.dg/parse/defarg8.C
===================================================================
--- testsuite/g++.dg/parse/defarg8.C (revision 262577)
+++ testsuite/g++.dg/parse/defarg8.C (working copy)
@@ -1,3 +1,5 @@
+// { dg-options "-fpermissive -w" }
+
struct A {
static void g(int);
};
