Re: [Boost-build] From where do compiler options come ?

Subject: Re: [Boost-build] From where do compiler options come ?
From: Edward Diener (eldiener_at_[hidden])
Date: 2015-10-16 01:42:19

On 9/29/2015 10:33 PM, Rene Rivera wrote:
>
>
> On Tue, Sep 29, 2015 at 9:19 PM, Edward Diener <eldiener_at_[hidden]
> <mailto:eldiener_at_[hidden]>> wrote:
>
>     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 at
>     http://www.boost.org/build/doc/html/bbv2/reference/tools.html#bbv2.reference.tools.compiler.gcc,
>     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 ).
>
>
> I think what you are after is toolset requirements
> <https://github.com/boostorg/build/blob/develop/src/build/toolset.jam#L574>.
> Which you could use by adding in your user-config.jam something like:
>
> ===
> import toolset ;
>
> using clang ;
>
> toolset.add-requirements <toolset>clang-linux:<warnings>off ;

Unfortunately this sometimes works, but not as a general solution. There 
are some libraries for which the above setup works fine, ie 'bind' or 
'preprocessor'. But if I try it for testing another library, ie. 
'function', I get instead:

> E:/Programming/VersionControl/modular-boost/tools/build/src/build\feature.jam:782: in expand-composites from module feature
> error: explicitly-specified values of non-free feature <warnings> conflict
> error: existing values: off on
> error: value from expanding  <warnings>on : on
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\feature.jam:867: in feature.expand from module feature
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:1070: in evaluate-requirements from module targets
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:1112: in common-properties2 from module targets
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:977: in targets.common-properties from module targets
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:1303: in class_at_basic-target.generate from module object(typed-target)@755
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:774: in generate-really from module object(main-target)@3915
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:746: in class_at_main-target.generate from module object(main-target)@3915
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:895: in targets.generate-from-reference from module targets
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:1266: in generate-dependencies from module object(typed-target)@2036
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:1323: in class_at_basic-target.generate from module object(typed-target)@2036
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:774: in generate-really from module object(main-target)@3898
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:746: in class_at_main-target.generate from module object(main-target)@3898
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:895: in targets.generate-from-reference from module targets
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:1266: in generate-dependencies from module object(typed-target)@1981
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:1320: in class_at_basic-target.generate from module object(typed-target)@1981
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:774: in generate-really from module object(main-target)@3359
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:746: in class_at_main-target.generate from module object(main-target)@3359
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:895: in targets.generate-from-reference from module targets
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:1266: in generate-dependencies from module object(typed-target)@2150
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:1323: in class_at_basic-target.generate from module object(typed-target)@2150
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:774: in generate-really from module object(main-target)@2239
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:746: in class_at_main-target.generate from module object(main-target)@2239
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:895: in targets.generate-from-reference from module targets
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:1266: in generate-dependencies from module object(alias-target-class)@2232
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:1323: in class_at_basic-target.generate from module object(alias-target-class)@2232
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:774: in generate-really from module object(main-target)@2260
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:746: in class_at_main-target.generate from module object(main-target)@2260
> E:/Programming/VersionControl/modular-boost/tools/build/src/build\targets.jam:272: in class_at_project-target.generate from module object(project-target)@2136
> E:/Programming/VersionControl/modular-boost/tools/build/src\build-system.jam:707: in load from module build-system
> E:\Programming\VersionControl\modular-boost\tools\build\src/kernel\modules.jam:295: in import from module modules
> E:\Programming\VersionControl\modular-boost\tools\build\src/kernel/bootstrap.jam:139: in boost-build from module
> E:\Programming\VersionControl\modular-boost\boost-build.jam:17: in module scope from module

Another of those vagaries of Boost Build which makes working with it so 
difficult. Evidently if I have <warnings>off in some place and 
<warnings>on in another place, there is a problem, although the 
occasions which trigger this problem are no doubt more of the Boost 
Build voodoo. For instance in the preprocessor test project requirements 
I specify '<warnings>on' but I do not get the errors above running the 
preprocessor tests. But with 'function' tests it does occur.