Re: [Boost-users] [format] warning...warning...warning

Subject: Re: [Boost-users] [format] warning...warning...warning
From: Oswin Krause (Oswin.Krause_at_[hidden])
Date: 2017-03-23 19:51:26

On 2017-03-23 16:43, Steven Watanabe via Boost-users wrote:
> AMDG
> 
> On 03/23/2017 02:45 AM, Arnaud RICHARD via Boost-users wrote:
>> Hello,
>> I'm a complete Boost newbie. I've been told very often that boost is 
>> the way to go for serious C++ coding, and I was not surprised to see 
>> such emphasis on the home page:
>> "We aim to establish "existing practice" and provide reference 
>> implementations so that Boost libraries are suitable for eventual 
>> standardization"
>> 
>> So when I used the format library on my existing (non-trivial) project 
>> and first compiled... I was very very surprised to get my neat 
>> compilation console flooded with hundreds of warnings !
>> 
>> I acknowledge I activate many many warnings:
>> CXXFLAGS+=-Wall -Wextra -Wcast-qual -Wctor-dtor-privacy 
>> -Wdisabled-optimization \
>>           -Wformat=2 -Winit-self -Wlogical-op -Wmissing-include-dirs \
>>           -Wnoexcept -Woverloaded-virtual -Wredundant-decls -Wshadow \
>>           -Wsign-conversion -Wsign-promo -Wstrict-null-sentinel 
>> -Wstrict-overflow=5 \
>>           -Wswitch-default -Wundef -Wunused
>> 
>> The warnings were as trivial as (for example):
>> ../ext/boost/boost/type_traits/is_default_constructible.hpp:16:22: 
>> warning: "BOOST_GCC_VERSION_WORKAROUND_GUARD" is not defined [-Wundef]
>> #if BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40700)
>> 
> 
>   If you compile with higher-than-default warning settings,
> it's simplest to include Boost with -isystem instead of -I.
> - At high warning settings, most additional warnings are spurious.
>   Fixing them is a lot of effort for little gain.
> - Every compiler warns about different issues.  Just because
>   the code compiles without warnings on one compiler doesn't
>   mean that other compilers will be equally happy.  There have
>   even been cases in the past where compiler A warned if
>   you did X, while compiler B warned if you /didn't/ do X.
> - Sometimes "fixing" spurious warnings can create new bugs.
> 
> With that being said, I personally try to explicitly suppress
> (with #pragma's) any known warnings that I don't care about.

Hi,

in this specific case the warning is not a false positive, or useless, 
at elast as far as i udnerstand it. BOOST_GCC_VERSION_WORKAROUND_GUARD 
is really not defined anywhere in boost, so this #ifdef block will never 
be used.
> 
>> ../ext/boost/boost/format/parsing.hpp:435:67: warning: conversion to 
>> 'std::vector<boost::io::detail::format_item<char, 
>> std::char_traits<char>, std::allocator<char> >, 
>> std::allocator<boost::io::detail::format_item<char, 
>> std::char_traits<char>, std::allocator<char> > > >::size_type {aka 
>> unsigned int}' from 'int' may change the sign of the result 
>> [-Wsign-conversion]
>>              string_type & piece = (cur_item==0) ? prefix_ : 
>> items_[cur_item-1].appendix_;
>> 
>> I understand they are only warning and the code is functionally 
>> correct and standard-wise correct.
>> Personally when I face such false warnings in my code, I change the 
>> code to remove the warning so that if a warning does make sense, I can 
>> notice it.
>> 
>> I thought a reference implementation would be written with such 
>> policy.
> 
> You really shouldn't expect even those who are pedantic about
> warnings to enable more than -Wall -Wextra.
> 
>> There's no way I'm gonna read each of the hundreds of messages to 
>> understand if it is a mistake in my source code or a "shortcut" in 
>> boost library.
>> 
>> So this is my first user experience. Not impressed at all. Boost will 
>> not be my reference.
>> 
> 
> In Christ,
> Steven Watanabe
> 
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