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Subject: Re: [Boost-build] From where do compiler options come ?
From: Edward Diener (eldiener_at_[hidden])
Date: 2015-09-29 22:19:05

On 9/29/2015 3:05 AM, Vladimir Prus wrote:
> On 29-Sep-15 9:57 AM, Vladimir Prus wrote:
>> On 28-Sep-15 11:25 PM, Vladimir Prus wrote:
>>> The priority order is roughly this:
>>> - default values, here warnings=on
>>> - properties on the command line, none in your case
>>> - requirements on projects and metatargets
>>> I am surprised you still get -Wall, I'll take look tomorrow.
>> Edward,
>> with the patch below, when I run "b2 --debug-building", I see that
>> <warnigns>off is in build properties. With msvc, I also see /W0, which
>> is the expected warning option. Could you try exactly same patch and see
>> whether -Wall is still there?
>> --- test/Jamfile
>> +++ test/Jamfile
>> @@ -15,7 +15,7 @@ project
>> ;
>> test-suite lambda
>> - : [ run algorithm_test.cpp ]
>> + : [ run algorithm_test.cpp : : : <warnings>off ]
>> [ run bind_tests_simple.cpp ]
>> [ run bind_tests_advanced.cpp ]
>> [ run bind_tests_simple_f_refs.cpp ]
> The same patch also eliminates -Wall on Ubuntu with gcc.

What I see is that I can override the -Wall default if I specify
"warnings=off" on the command line. Also if either the jam file has
project requirements with "<warnings>off" or individual target has the
"<warnings>off" the -Wall default is overridden.

However evidently, as specified in the documentation for the gcc toolset
the end-user can not use "<warnings>off" ( or any "<warnings>" option )
at the toolset level. I am trying to use it for clang, not gcc, but
there is no documentation for the clang toolset in the Boost Build docs
so I assume the same restriction goes for clang. Is there a reason why
general requirements could not be part of the 'using' rule aside from
the fact that it was not designed that way ? It would surely be useful
to specify any feature, and not just the limited features which are
direct compiler options, in the 'using' rule. I think the end-user
should be able to specify a general requirement for his toolset which
overrides the default requirement. My particular need is that clang
outputs an awful lot of detail even when warnings occur, so I would like
to limit as an end-user the warnings for that compiler. Doing it on the
command line is possible but it is much easier if I could do it at the
toolset level and treat the command line generically as to the toolset (
which is what I currently do by invoking 'b2' from batch files ).

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