MSVC: Regression cross compiling from x86_64 to x86

[alexcrichton]

On nightly (and beta I believe) the compiler will currently fail when cross compiling from x86_64 to x86 (after ensuring the standard library is in the right location) with the message:

note: "C:\\Program Files (x86)\\Microsoft Visual Studio 12.0\\VC\\bin\\amd64_x86\\link.exe" "/LIBPATH:C:\\Program Files (x86)\\Microsoft Visual Studio 12.0\\VC\\lib\\" "/LIBPATH:C:\\Program Files (x86)\\Windows Kits\\8.1\\lib\\winv6.3\\um\\x86" "/NOLOGO" "/NXCOMPAT" "/LIBPATH:C:\\bot\\slave\\cargo-win-msvc-64\\build\\rustc\\lib\\rustlib\\i686-pc-windows-msvc\\lib" "C:\\bot\\slave\\cargo-win-msvc-64\\build\\target\\cit\\t288\\foo\\target\\i686-pc-windows-msvc\\debug\\foo.0.o" "/OUT:C:\\bot\\slave\\cargo-win-msvc-64\\build\\target\\cit\\t288\\foo\\target\\i686-pc-windows-msvc\\debug\\foo.exe" "/OPT:REF,ICF" "/DEBUG" "/LIBPATH:C:\\bot\\slave\\cargo-win-msvc-64\\build\\target\\cit\\t288\\foo\\target\\i686-pc-windows-msvc\\debug" "/LIBPATH:C:\\bot\\slave\\cargo-win-msvc-64\\build\\target\\cit\\t288\\foo\\target\\i686-pc-windows-msvc\\debug\\deps" "/LIBPATH:C:\\bot\\slave\\cargo-win-msvc-64\\build\\rustc\\lib\\rustlib\\i686-pc-windows-msvc\\lib" "C:\\bot\\slave\\cargo-win-msvc-64\\build\\target\\cit\\t288\\foo\\target\\i686-pc-windows-msvc\\debug\\deps\\libbaz-5766ea894e3b2228.rlib" "C:\\bot\\slave\\cargo-win-msvc-64\\build\\rustc\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\libstd-17a8ccbd.rlib" "C:\\bot\\slave\\cargo-win-msvc-64\\build\\rustc\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\libcollections-17a8ccbd.rlib" "C:\\bot\\slave\\cargo-win-msvc-64\\build\\rustc\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\librustc_unicode-17a8ccbd.rlib" "C:\\bot\\slave\\cargo-win-msvc-64\\build\\rustc\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\librand-17a8ccbd.rlib" "C:\\bot\\slave\\cargo-win-msvc-64\\build\\rustc\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\liballoc-17a8ccbd.rlib" "C:\\bot\\slave\\cargo-win-msvc-64\\build\\rustc\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\liballoc_system-17a8ccbd.rlib" "C:\\bot\\slave\\cargo-win-msvc-64\\build\\rustc\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\liblibc-17a8ccbd.rlib" "C:\\bot\\slave\\cargo-win-msvc-64\\build\\rustc\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\libcore-17a8ccbd.rlib" "ws2_32.lib" "userenv.lib" "shell32.lib" "advapi32.lib" "msvcrt.lib" "compiler-rt.lib"
note: LINK : fatal error LNK1171: unable to load mspdbst.dll (error code: 126)

I believe this is a regression from #30233 and #30516, which were backported, so I believe this is a stable regression. That being said I doubt anyone other than Cargo CI is doing this, so it may not be that big.

I also believe that @retep998 is working on a patch, but this should help track this issue.

[briansmith]

That being said I doubt anyone other than Cargo CI is doing this, so it may not be that big.

I have been doing this with ring and ring-based projects for many months.