Re: Bad comments in msvc.jam?

From: David Abrahams (dave_at_[hidden])
Date: 2005-05-24 11:36:32

Vladimir Prus <ghost_at_[hidden]> writes:

> On Tuesday 24 May 2005 18:04, David Abrahams wrote:
>> This comment appears to be extremely misleading.
>>
>> # The following options work only for 7* versions. It means
>> # that if the user has not specified a version he gets 6.0 compatible
>> # behavious (i.e. a bit buggy)
>> if [ MATCH ^(7\..*) : $(version) ]
>> {
>> flags msvc.compile CFLAGS $(condition) : /Zc:forScope /Zc:wchar_t ;
>> }
>>
>>
>> AFAICT, this means that an vc7* gives vc6 compatible for loop and
>> wchar_t behaviors by default and that we're overriding that.
>>
>> The comment appears to state that if the user only has version 7 or
>> 7.1 installed, but doesn't specify a version, he'll get vc6-compatible
>> behavior from Boost.Build. AFAICT that is a lie unless we're also
>> unable to detect which version he has installed.
>
> The exact meaning of the above comment is this:
>
> 1. vc7 does have /Zc:forScope and /Zc:wchar_t by default

You need to be clearer. When you say vc7 you mean msvc-7.x as
presented by the build system, or do you mean the command-line
compiler given by microsoft? And when you say "does have" do you mean
that the options are available by default, or that they're enabled by
default?

If they're enabled by default, why would we bother adding them
explicitly? That doesn't make any sense, so you must mean that
they're available by default. But then what does "by default" mean?
In vc7 they're either available or they're unavailable. I happen to
know that they're available in vc7, but that doesn't help me
understand anything you're trying to say.

> 2. vc6 does not have those options at all.
> 3. Unless we're sure that we are dealing with vc7, we don't add those
> options.
> 4. We can be sure it's vc7 either if user specified 7.* as version, or
> we have found 7.* in install path.
>
>
> Hope this clarifies the matter,
> Volodya

Not yet. And the comment in the toolset file is still just as
hard to understand as it was before.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com