llvm dev - Nov 2013 - [LLVMdev] [cfe-dev] RFC: A proposal to move toward using C++11 features in LLVM & Clang / bounding support for old host compilers

On 11/ 7/13 12:27 AM, Tim Northover wrote:
>>> If the new feature requires out-of-tree LLVM users to upgrade their
>>> toolchains then we may only be giving them a month or less warning,
>>> even if we are giving downstream packagers 6 months.
>> Correct.  That's not enough warning.
> If we decide to delay this yet again (it's been on the cards since
> January, so I'm personally opposed, but still...) we should at least
> start counting the "acceptable notice" from the start of this
thread
> rather than when the dust settles.
because a discussion starts - and the Tea party wants their way.. it 
doesn't mean it's final. I'd love to ignore this thread until
something
is actually announced... with "proper" notice..

// I still don't get the fire everyone is trying to put out...

On Wed, Nov 6, 2013 at 5:38 PM, "C. Bergström" <cbergstrom at
pathscale.com>wrote:
> On 11/ 7/13 12:27 AM, Tim Northover wrote:
>
>> If the new feature requires out-of-tree LLVM users to upgrade their
>>>> toolchains then we may only be giving them a month or less
warning,
>>>> even if we are giving downstream packagers 6 months.
>>>>
>>> Correct.  That's not enough warning.
>>>
>> If we decide to delay this yet again (it's been on the cards since
>> January, so I'm personally opposed, but still...) we should at
least
>> start counting the "acceptable notice" from the start of this
thread
>> rather than when the dust settles.
>>
> because a discussion starts - and the Tea party wants their way.. it
> doesn't mean it's final. I'd love to ignore this thread until
something is
> actually announced... with "proper" notice..
>
A personal question: is there any way we could modify some part of the
build to do some of the "non-fatal but difficult to ignore"
announcement if
the building compiler can't handle the upcoming constructs? Eg, just
thinking off the top of my head here, could we abuse the make check/lit
mechanism to get a file with C++11 features that are going to be used in X
months compiled with the building compiler, so that people running projects
following ToT and who run "make check" regularly will get a new
failure if
they'll be facing problems ahead? I suspect actually using the tests would
be more trouble than it's worth in terms of public buildbots, but something
that showed that there was an upcoming issue that happened each time you
rebuilt LLVM as you follow ToT might help keep the mandatory warning period
from becoming really high.

-- 
cheers, dave tweed__________________________
high-performance computing and machine vision expert: david.tweed at gmail.com
"while having code so boring anyone can maintain it, use Python." --
attempted insult seen on slashdot
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David Tweed <david.tweed at gmail.com> writes:
> A personal question: is there any way we could modify some part of the
> build to do some of the "non-fatal but difficult to ignore"
> announcement if the building compiler can't handle the upcoming
> constructs? Eg, just thinking off the top of my head here, could we
> abuse the make check/lit mechanism to get a file with C++11 features
> that are going to be used in X months compiled with the building
> compiler, so that people running projects following ToT and who run
> "make check" regularly will get a new failure if they'll be
facing
> problems ahead?
This wouldn't address the main issue as I see it.  I am not worried at
all about LLVM and whether I'll be able to build it with a new toolchain
on our machines.  I'm worried about everything *else* we have integrated
with LLVM that will also need to be built with the new toolchain.  It's
all that other stuff that we need to be able to test before LLVM forces
us to use a new toolchain.

When the LLVM 3.4 release is cut, I'm simply asking that we don't start
using stuff that requires a new toolchain right away.  If we could wait
3-4 months that would allow time for testing.  We can still require a
new toolchain for the 3.5 release, allow C++-11, etc..  We just
shouldn't require it on ToT right away.

                            -David