RE: Is it possible not to use snprintf or any other stdio functionalities to throw std::logic_error in standard library containers?

[unlvsur unlvsur <unlvsur@live.com>]

// I have disabled libstdcxx verbose

#include<fast_io.h>

int main(int argc,char** argv)
{
                std::string_view str(*argv);
                puts(str.substr(4).data());
}

g++ -o b b.cc -Ofast -std=c++20 -s -flto -march=native -I../fast_io/include -static-libstdc++

binary size 86kb


#include<fast_io.h>

int main(int argc,char** argv)
{
                std::string_view str(*argv);
                if(str.size()<4)
                                __builtin_trap();
                puts(std::string_view(str.data()+4,str.size()).data());
}

g++ -o c c.cc -Ofast -std=c++20 -s -flto -march=native -I../fast_io/include -static-libstdc++

binary size 15kb



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From: Jonathan Wakely<mailto:jwakely@redhat.com>
Sent: Thursday, May 20, 2021 15:35
To: unlvsur unlvsur<mailto:unlvsur@live.com>
Cc: unlvsur unlvsur via Libstdc++<mailto:libstdc++@gcc.gnu.org>
Subject: Re: Is it possible not to use snprintf or any other stdio functionalities to throw std::logic_error in standard library containers?

On 20/05/21 19:27 +0000, unlvsur unlvsur wrote:
>Well. It comes from snprintf. You cannot use any stdio functionalities.
>
>For example
>https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fgcc-mirror%2Fgcc%2Fblob%2F4f4a2f199baf46d35492edadc16f30f32920c4df%2Flibstdc%252B%252B-v3%2Finclude%2Fbits%2Fstl_vector.h%23L1070&amp;data=04%7C01%7C%7C5e592cf75b1a4524c05408d91bc66216%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637571361118589300%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=5OZqIYtKRzXDWOcATMsIrBBYjCJOupkxk0of7SagS%2FQ%3D&amp;reserved=0

But that doesn't use snprintf.

>
>https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fgcc-mirror%2Fgcc%2Fblob%2F16e2427f50c208dfe07d07f18009969502c25dc8%2Flibstdc%252B%252B-v3%2Finclude%2Fexperimental%2Fstring_view%23L274&amp;data=04%7C01%7C%7C5e592cf75b1a4524c05408d91bc66216%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637571361118589300%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=iukICKyYF0pB1qJv16vCcZpXrbpBhzK%2FPteRZAEZx3U%3D&amp;reserved=0

And that doesn't use snprintf either.

Have you actually seen a dependency on stdio from these functions, or
are you just assuming?

>We need something which is a silent EH thrown, this format string thrown stuff will always introduce dependencies silently.
>
>This also hurts optimizations
>
>[cid:image002.png@01D74D8C.9AD99570]
>
>
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>
>From: Jonathan Wakely<mailto:jwakely@redhat.com>
>Sent: Thursday, May 20, 2021 15:21
>To: Jonathan Wakely<mailto:jwakely.gcc@gmail.com>
>Cc: unlvsur unlvsur<mailto:unlvsur@live.com>; unlvsur unlvsur via Libstdc++<mailto:libstdc++@gcc.gnu.org>
>Subject: Re: Is it possible not to use snprintf or any other stdio functionalities to throw std::logic_error in standard library containers?
>
>On 15/05/21 09:23 +0100, Jonathan Wakely via Libstdc++ wrote:
>>On Sat, 15 May 2021, 04:12 unlvsur unlvsur via Libstdc++, <
>>libstdc++@gcc.gnu.org> wrote:
>>
>>> The issue is that this will silently introduce dependency to stdio. On
>>> MinGW-w64 for example, any snprintf function call will bloat binary size
>>> for 70kb, that is even we shared linking with both msvcrt and libstdc++.
>>>
>>> I frequently see a random bloat because of that.
>>>
>>> By the way, it also hurts optimizations since compilers cannot merge them
>>> together.
>>>
>>> Better just throw an exception with “vector<T> out of bounds” instead of
>>> formatting subscriptor.
>>>
>>
>>
>>I can make that depend on the _GLIBCXX_VERBOSE macro.
>
>Where is the dependency on stdio coming from though? Formatting the
>exception string doesn't use stdio.
>