[llvm-dev] Can we start using std::to_string?

[Pavel Labath via llvm-dev]

Hello all,

it took a a bit longer than I hoped, but I am nonetheless pleased to
report that our dependency on the version of libstdc++ with broken
std::to_string has been removed. The android bot now builds lldb with
clang and libc++.

I'm not sure if there are any other obstacles preventing us from using
std::to_string, but we are not one of them.

regards,
pavel

On 17 May 2017 at 18:34, Tamas Berghammer <tberghammer at google.com> wrote:
> The Android NDK currently ships with gcc 4.9.2 what should support
> std::to_string but there are some issues regarding the implementation of it.
> The root cause is that complex.h is missing some function from the Android
> libc (bionic) what results in _GLIBCXX_USE_C99 not being defined what will
> disable access to a set of string conversion functions (including
> std::to_string).
>
> 2 relevant bug for the Android NDK:
> https://github.com/android-ndk/ndk/issues/82
> https://issuetracker.google.com/issues/37015480
>
> Tamas
>
> On Wed, May 17, 2017 at 2:52 PM 陳韋任 <chenwj.cs97g at g2.nctu.edu.tw> wrote:
>>
>> Maybe it's time to update the Requirements section on Getting Started with
>> the LLVM System [1]?
>>
>> [1]
>> http://llvm.org/docs/GettingStarted.html#host-c-toolchain-both-compiler-and-standard-library
>>
>> 2017-05-17 21:44 GMT+08:00 Hal Finkel via llvm-dev
>> <llvm-dev at lists.llvm.org>:
>>>
>>> I'm fairly sure the problem is that we still support building with gcc
>>> 4.8.x, and that version of gcc did not have std::to_string. It is not just
>>> an NDK issue.
>>>
>>>  -Hal
>>>
>>>
>>> On 05/17/2017 06:05 AM, Pavel Labath via llvm-dev wrote:
>>>>
>>>> Hi Diana,
>>>>
>>>> I am responsible for that bot, and probably a great number of those
>>>> fixups.
>>>>
>>>> The root of the problem is that android NDK comes with a libstdc++
>>>> which does not have std::to_string. I forgot the exact reason but Dan
>>>> or Tamas (cc'ed) should know it. The NDK also comes with libc++, which
>>>> does have working std::to_string, but this one is not compatible with
>>>> older android devices. This part is being actively worked on though. I
>>>> am going to sync up with Dan to see if I can give you any timeline on
>>>> that.
>>>>
>>>> And yes, the bot does not build the AVR and other backends, that's why
>>>> we get no std::string errors there.
>>>>
>>>>
>>>>
>>>> On 17 May 2017 at 11:12, Diana Picus via llvm-dev
>>>> <llvm-dev at lists.llvm.org> wrote:
>>>>>
>>>>> Hi all,
>>>>>
>>>>> I tried to use std::to_string somewhere and one of the bots yelled at
>>>>> me [1] because it couldn't find it.
>>>>>
>>>>> Searching through the mailing lists reveals a long stream of fixup
>>>>> patches trying to avoid std::to_string, but there are uses of it in
>>>>> tree in the AVR and Hexagon backends, libFuzzer and the Gold plugin. I
>>>>> can only imagine they got away with it because the particular bots
>>>>> that can't find std::to_string are probably not building them.
>>>>>
>>>>> Should we fix the bots and remove llvm::to_string? Or is it still too
>>>>> soon?
>>>>> Alternatively, should we replace all uses of std::to_string with
>>>>> llvm::to_string?
>>>>>
>>>>> Cheers,
>>>>> Diana
>>>>>
>>>>> [1]
>>>>> http://lab.llvm.org:8011/builders/lldb-x86_64-ubuntu-14.04-buildserver/builds/8853/steps/build%20android/logs/stdio
>>>>> _______________________________________________
>>>>> LLVM Developers mailing list
>>>>> llvm-dev at lists.llvm.org
>>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>
>>>> _______________________________________________
>>>> LLVM Developers mailing list
>>>> llvm-dev at lists.llvm.org
>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>
>>>
>>> --
>>> Hal Finkel
>>> Lead, Compiler Technology and Programming Languages
>>> Leadership Computing Facility
>>> Argonne National Laboratory
>>>
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>>
>>
>>
>> --
>> Wei-Ren Chen (陳韋任)
>> Homepage: https://people.cs.nctu.edu.tw/~chenwj