From: Jonathan Wakely <jwakely.gcc@gmail.com>
To: Stephan Bergmann <sbergman@redhat.com>
Cc: "gcc@gcc.gnu.org" <gcc@gcc.gnu.org>
Subject: Re: gdb 8.x - g++ 7.x compatibility
Date: Mon, 05 Feb 2018 10:59:00 -0000 [thread overview]
Message-ID: <CAH6eHdSoGdEiNk1qn0m+vSDQxavVrKY6fBVTtGmr4e6hYkzVbg@mail.gmail.com> (raw)
In-Reply-To: <32005e43-38f6-dc03-b1ac-25bf93a4b4f5@redhat.com>
On 5 February 2018 at 09:16, Stephan Bergmann wrote:
> On 05.02.2018 06:06, Simon Marchi wrote:
>>
>> On 2018-02-04 02:17 PM, Martin Sebor wrote:
>>>
>>> Printing the suffix is unhelpful because it leads to unnecessary
>>> differences in diagnostics (even in non-template contexts). For
>>> templates with non-type template parameters there is no difference
>>> between, say A<1>, A<1U>, A<(unsigned) 1>, or even A<Green> when
>>> Green is an enumerator that evaluates to 1, so including the suffix
>>> serves no useful purpose.
>>
>>
>> This is the part I don't understand. In Roman's example, spelling
>> foo<10> and foo<10u> resulted in two different instantiations of the
>> template, with different code. So that means it can make a difference,
>> can't it?
>
>
> Yes, for non-type template parameters whose type contains a placeholder type
> (i.e., "auto IVAL" in the earlier example), which is a new feature of C++17.
Right, for C++14 saying foo<2> is entirely unambiguous because the
type of the template parameter is fixed. For C++17 a template declared
as "template<auto> class foo" can be instantiated with different
types, so foo<2> and foo<2u> don't refer to the same specialiation.
> My understanding is that printing the suffix would be essential in such
> cases.
Not sufficient, it doesn't help distinguish foo<(short)2>, foo<(int)2>
or foo<(signed char)2> because there is no suffix for signed/unsigned
short or signed/unsigned char.
next prev parent reply other threads:[~2018-02-05 10:59 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-03 3:17 Roman Popov
2018-02-03 3:57 ` carl hansen
2018-02-03 4:54 ` Simon Marchi
2018-02-03 5:02 ` Roman Popov
2018-02-03 6:43 ` Roman Popov
2018-02-03 14:20 ` Paul Smith
2018-02-03 17:18 ` Roman Popov
2018-02-03 18:36 ` Manfred
2018-02-04 5:01 ` Simon Marchi
2018-02-04 17:09 ` Manfred
2018-02-04 19:17 ` Martin Sebor
2018-02-05 5:07 ` Simon Marchi
2018-02-05 9:16 ` Stephan Bergmann
2018-02-05 10:59 ` Jonathan Wakely [this message]
2018-02-05 16:45 ` Martin Sebor
2018-02-05 16:59 ` Simon Marchi
2018-02-05 17:44 ` Roman Popov
2018-02-05 20:08 ` Jonathan Wakely
2018-02-05 20:10 ` Roman Popov
2018-02-05 20:12 ` Jonathan Wakely
2018-02-05 20:17 ` Roman Popov
2018-02-06 3:52 ` Martin Sebor
2018-02-07 7:21 ` Daniel Berlin
2018-02-07 13:44 ` Simon Marchi
2018-02-07 15:07 ` Manfred
2018-02-07 15:16 ` Jonathan Wakely
2018-02-07 16:19 ` Manfred
2018-02-07 16:26 ` Michael Matz
2018-02-07 16:36 ` Simon Marchi
2018-02-07 16:51 ` Jonathan Wakely
2018-02-07 17:13 ` Simon Marchi
2018-02-07 17:08 ` Jonathan Wakely
2018-02-07 17:20 ` Simon Marchi
2018-02-07 17:30 ` Jonathan Wakely
2018-02-07 18:28 ` Simon Marchi
2018-02-08 11:26 ` Michael Matz
2018-02-08 14:05 ` Paul Smith
2018-02-08 14:07 ` Jonathan Wakely
2018-02-07 17:31 ` Marc Glisse
2018-02-07 17:04 ` Daniel Berlin
2018-02-07 17:11 ` Daniel Berlin
2018-02-07 22:00 ` Nathan Sidwell
2018-02-07 20:29 ` Tom Tromey
2018-02-08 15:05 ` Richard Biener
2018-03-01 20:18 ` Roman Popov
2018-03-01 20:26 ` Andrew Pinski
2018-03-01 21:03 ` Jason Merrill
2018-03-02 23:06 ` Roman Popov
2018-03-03 4:01 ` Roman Popov
2018-03-04 4:28 ` Daniel Berlin
2018-02-05 11:05 ` Jonathan Wakely
2018-02-07 15:19 ` Jonathan Wakely
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