It seems fairly self-evident that tor hasn't been build for 64-bit windows and questionable whether it's ever been built in an environment that doesn't utilize mingw. [...]
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AFAIK, Tor has only been compiled as a Win32 app, never as a Win64 app.
I realize that many/most/all of the developers here are going to see no problem with using mingw, but if you spend some time looking underneath the hood and reviewing the code generated by mingw v. msvc both in terms of security features and general performance, [...]
In the past, most of the time, Tor only builds on Windows with GCC/MinGW. But recently,
Tor works primarily on Windows via MinGW toolchain, AFAIK still MinGW32. It has worked a few times in the past, in the last few weeks, another update was made for MSVC (Win32), and hopefully that still works with trunk.
Re: security, Tor has most of the modern exe image flags properly tweaked with GCC toolchain. But not with MSVC toolchain. IMO, that'd be a nice patch, for MSVC build. But not too serious since Tor doesn't ship any MSVC-based distros, only GCC-based ones, as public binaries.
I think the issue is not MSVC -vs- GCC, but Win32 -vs- Win64, if they're willing to take all those kinds of patches.
And the additional burden for them to distribute 2* the Windows packages, both Win32 and Win64.
It *might* be an issue that Thandy is also probably only Win32, and might also need to be ported, when updating the WIX/NSIS installer scripts (Thandy gets called from within some of those scripts).
On the positive side, it seems like many Win32 projects get about 15% faster (when run on NT64 systems, removing the overhead of the Win32 subsystem) ..at least looking at use of MSVC toolchain, unclear about MinGW64 toolchain. So there's a chance that these patches would mean Windows Tor perf could get 15% better on modern (NT64-based: all servers, most desktops, and some mobile devices) Windows boxen. :-)