llvm dev - Aug 2014 - [LLVMdev] [RFC] Raising minimum required Visual Studio version to 2013 for trunk

On Fri, Aug 22, 2014 at 8:58 AM, Renato Golin <renato.golin at linaro.org>
wrote:
> On 22 August 2014 13:43, Aaron Ballman <aaron at aaronballman.com>
wrote:
>> My opposition to this switch was the timing. When we researched
"what
>> minimum can we live with for C++11" nine months ago, we determined
>> what versions would make sense, which included MSVC 2012, and told
>> people what the plan was. My concern was pulling the rug out from
>> under people who were relying on that determination without putting in
>> the proper research and giving them enough time to react.
>
> The fact that you spoke, and others echoed your views, is proof that
> what you fear will not happen.
>
> Chandler's plan is simply showing the failures before we switch, which
> is exactly what we've done last time, what you're asking now, and
what
> we'll do next.
>
> Progress is made by breaking small things, one at a time. :)
We're in violent agreement. :-)

~Aaron

Hi,
Sorry for the delay in responding, we have been discussing this internally
and have not had time to do a proper investigation.
> We absolutely have to ship a set of DLLs that run hosted in VS2012. Is 
> there any sort of runtime incompatibility that would happen if we 
> built with 2013, needed the 2013 CRT, but tried to run inside the 
> VS2012 process? That would be a complete show stopper for us since we 
> have a committed schedule for support of versions of VS that we host in.
> Has any size/performance testing been done to compare LLVM built with 
> the two versions of MSVC? Perf regressions are bad, m'kay?
I do not know the answer to either of Alex's questions, so I am a bit
concerned. Two weeks is not going to be enough to test the updates; two
months might be more realistic...

What is the impact on the static libraries (such as LLVMCore.lib or
ClangLex.lib)? Can libraries built with Visual Studio 2013 link with other
objects built with Visual Studio 2012 or earlier?

- Gao


-----Original Message-----
From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On
Behalf Of Aaron Ballman
Sent: Friday, August 22, 2014 6:01 AM
To: Renato Golin
Cc: LLVM Developers Mailing List
Subject: Re: [LLVMdev] [RFC] Raising minimum required Visual Studio version to
2013 for trunk

On Fri, Aug 22, 2014 at 8:58 AM, Renato Golin <renato.golin at linaro.org>
wrote:
> On 22 August 2014 13:43, Aaron Ballman <aaron at aaronballman.com>
wrote:
>> My opposition to this switch was the timing. When we researched
"what
>> minimum can we live with for C++11" nine months ago, we determined
>> what versions would make sense, which included MSVC 2012, and told 
>> people what the plan was. My concern was pulling the rug out from 
>> under people who were relying on that determination without putting 
>> in the proper research and giving them enough time to react.
>
> The fact that you spoke, and others echoed your views, is proof that 
> what you fear will not happen.
>
> Chandler's plan is simply showing the failures before we switch, which 
> is exactly what we've done last time, what you're asking now, and
what
> we'll do next.
>
> Progress is made by breaking small things, one at a time. :)
We're in violent agreement. :-)

~Aaron
_______________________________________________
LLVM Developers mailing list
LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

On Mon, Aug 25, 2014 at 12:04 PM, Gao, Yunzhong
<yunzhong_gao at playstation.sony.com> wrote:
> Hi,
> Sorry for the delay in responding, we have been discussing this internally
> and have not had time to do a proper investigation.
>
>> We absolutely have to ship a set of DLLs that run hosted in VS2012. Is
>> there any sort of runtime incompatibility that would happen if we
>> built with 2013, needed the 2013 CRT, but tried to run inside the
>> VS2012 process? That would be a complete show stopper for us since we
>> have a committed schedule for support of versions of VS that we host
in.
>
>> Has any size/performance testing been done to compare LLVM built with
>> the two versions of MSVC? Perf regressions are bad, m'kay?
>
> I do not know the answer to either of Alex's questions, so I am a bit
> concerned. Two weeks is not going to be enough to test the updates; two
> months might be more realistic...
>
> What is the impact on the static libraries (such as LLVMCore.lib or
> ClangLex.lib)? Can libraries built with Visual Studio 2013 link with other
> objects built with Visual Studio 2012 or earlier?
>
> - Gao
No, you cannot link C++ code compiled with one version of VS to C++
code compiled with a different version of VS. The C++ ABI and standard
library change between versions.

- Michael Spencer
>
>
> -----Original Message-----
> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at
cs.uiuc.edu] On Behalf Of Aaron Ballman
> Sent: Friday, August 22, 2014 6:01 AM
> To: Renato Golin
> Cc: LLVM Developers Mailing List
> Subject: Re: [LLVMdev] [RFC] Raising minimum required Visual Studio version
to 2013 for trunk
>
> On Fri, Aug 22, 2014 at 8:58 AM, Renato Golin <renato.golin at
linaro.org> wrote:
>> On 22 August 2014 13:43, Aaron Ballman <aaron at
aaronballman.com> wrote:
>>> My opposition to this switch was the timing. When we researched
"what
>>> minimum can we live with for C++11" nine months ago, we
determined
>>> what versions would make sense, which included MSVC 2012, and told
>>> people what the plan was. My concern was pulling the rug out from
>>> under people who were relying on that determination without putting
>>> in the proper research and giving them enough time to react.
>>
>> The fact that you spoke, and others echoed your views, is proof that
>> what you fear will not happen.
>>
>> Chandler's plan is simply showing the failures before we switch,
which
>> is exactly what we've done last time, what you're asking now,
and what
>> we'll do next.
>>
>> Progress is made by breaking small things, one at a time. :)
>
> We're in violent agreement. :-)
>
> ~Aaron
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

On 25 August 2014 20:04, Gao, Yunzhong
<yunzhong_gao at playstation.sony.com> wrote:
> I do not know the answer to either of Alex's questions, so I am a bit
> concerned. Two weeks is not going to be enough to test the updates; two
> months might be more realistic...
Two months look very reasonable to me.

This is not a critical move, so we should do it one step at a time.
But it is an important move, so we should actually do it, preferably a
few months before 3.6 branches out.

cheers,
--renato