[Boost-build] Building with VC++ using address-model=64

Subject: [Boost-build] Building with VC++ using address-model=64
From: Edward Diener (eldiener_at_[hidden])
Date: 2013-05-17 20:45:00

I am on a 64-bit system running Windows 7 Ultimate 64-bit. I invoke:

"bjam address-model=64 toolset=msvc-9.0"

Boost build does invoke the VC++ 9 to build a 64 bit executable. But it 
uses the 'x86_amd64' option to vcvarsall.bat, invoking the 32-bit 
compiler to build the 64-bit executable rather than the 'amd64' option 
to invoke the 64-bit compiler to build the 64-bit executable. The 
documentation for the VC++ toolset says:

"The (AMD64 host, AMD64 target) compiler will be used automatically when 
you are generating AMD64 code and are running 64-bit Windows on AMD64."

But this is not happening in my case and I am most certainly running 
64-bit Windows 7.

Is this a bug in Boost Build ?
Is there a way I can force Boost Build to use the 64-bit compiler to 
generate the 64-bit executable ?