This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
C++ PATCH to disable -fdeduce-init-list by default
- From: Jason Merrill <jason at redhat dot com>
- To: gcc-patches List <gcc-patches at gcc dot gnu dot org>
- Date: Tue, 01 Nov 2011 00:02:19 -0400
- Subject: C++ PATCH to disable -fdeduce-init-list by default
In my implementation of the C++11 list-initialization proposal, I also
implemented an extension that allowed for deduction of
std::initializer_list<...> for a template type parameter, so that people
could try it out and see what they thought. This extension didn't make
it into C++11, so I'm switching its flag to be off by default.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit 03e84320fcb7868a31016c7cb80596e38a5183d5
Author: Jason Merrill <jason@redhat.com>
Date: Mon Oct 31 22:02:29 2011 -0400
* c.opt (-fdeduce-init-list): Off by default.
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 336a75a..6d50097 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -752,8 +752,8 @@ C ObjC C++ ObjC++
Emit debug annotations during preprocessing
fdeduce-init-list
-C++ ObjC++ Var(flag_deduce_init_list) Init(1)
--fno-deduce-init-list disable deduction of std::initializer_list for a template type parameter from a brace-enclosed initializer-list
+C++ ObjC++ Var(flag_deduce_init_list) Init(0)
+-fdeduce-init-list enable deduction of std::initializer_list for a template type parameter from a brace-enclosed initializer-list
fdefault-inline
C++ ObjC++ Ignore
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 0c97453..2836b74 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -1907,9 +1907,9 @@ to @var{n}. A limit is needed to detect endless recursion during
constant expression evaluation. The minimum specified by the standard
is 512.
-@item -fno-deduce-init-list
-@opindex fno-deduce-init-list
-Disable deduction of a template type parameter as
+@item -fdeduce-init-list
+@opindex fdeduce-init-list
+Enable deduction of a template type parameter as
std::initializer_list from a brace-enclosed initializer list, i.e.
@smallexample
@@ -1924,9 +1924,10 @@ void f()
@}
@end smallexample
-This option is present because this deduction is an extension to the
-current specification in the C++0x working draft, and there was
-some concern about potential overload resolution problems.
+This deduction was implemented as a possible extension to the
+originally proposed semantics for the C++11 standard, but was not part
+of the final standard, so it is disabled by default. This option is
+deprecated, and may be removed in a future version of G++.
@item -ffriend-injection
@opindex ffriend-injection
diff --git a/gcc/testsuite/g++.dg/cpp0x/initlist-deduce.C b/gcc/testsuite/g++.dg/cpp0x/initlist-deduce.C
index e422132..373044f 100644
--- a/gcc/testsuite/g++.dg/cpp0x/initlist-deduce.C
+++ b/gcc/testsuite/g++.dg/cpp0x/initlist-deduce.C
@@ -2,7 +2,7 @@
// supported by the working draft, but is necessary for perfect forwarding
// of initializer-lists to things that can take a std::initializer_list.
-// { dg-options -std=c++0x }
+// { dg-options "-std=c++0x -fdeduce-init-list" }
// { dg-do run }
#include <initializer_list>