Upstream neersighted's patch for cross-compiling Rust for Windows

neersighted's Rust patch for cross-compiling Rust for Windows which we ship (https://gitweb.torproject.org/builders/tor-browser-build.git/tree/projects/rust/unwind.patch?h=maint-8.0) is working for us and we should upstream it.

added GeorgKoppen201810 component::applications/tor browser owner::tbb-team priority::medium resolution::wontfix severity::normal status::closed type::task labels

Posted at https://github.com/rust-lang/rust/pull/55444

Trac:
Username: manish.earth

As an update here, I've been commenting (https://github.com/rust-lang/rust/pull/55444#issuecomment-434015059) on that PR, but unfortunately this patch I don't think we can land upstream because it doesn't really produce a workable target (panics don't run destructors).

For Tor though how much of this actually matters? I was under the impression that Firefox compiles with -C panic=abort which would bypass the exception runtime anyway. Does tor also do that or intentionally not do that? (or accidentally forget to pass a flag that does that?) Or does -C panic=abort still have linking issues?

Trac:
Username: alexcrichton

Oh it looks like there's a project in the Rust community which has a script - https://github.com/rust-embedded/cross/blob/master/docker/mingw.sh - which compiles a mingw with dwarf exception support? That may also be useful here!

Trac:
Username: alexcrichton

Replying to alexcrichton:

As an update here, I've been commenting (https://github.com/rust-lang/rust/pull/55444#issuecomment-434015059) on that PR, but unfortunately this patch I don't think we can land upstream because it doesn't really produce a workable target (panics don't run destructors).

For Tor though how much of this actually matters? I was under the impression that Firefox compiles with -C panic=abort which would bypass the exception runtime anyway. Does tor also do that or intentionally not do that? (or accidentally forget to pass a flag that does that?) Or does -C panic=abort still have linking issues?

Firefox is fine. The problem is that we don't get a properly functioning rust compiler compiled for the i686 mingw target due to the exception handling issue (compiling with panic=abort does not work and panic=unwind is broken as well). See: #26329 (moved) and #25894 (moved) for more context. And we build the compiler from source partly because we expected that we needed to deal with issues like #26475 (moved). :)

Replying to alexcrichton:

Oh it looks like there's a project in the Rust community which has a script - https://github.com/rust-embedded/cross/blob/master/docker/mingw.sh - which compiles a mingw with dwarf exception support? That may also be useful here!

I agree and I agree with the reasoning for not upstreaming the patch. I opened #28240 (moved) for thinking about compiling with dwarf exception support.

However, we plan to switch to a new mingw-w64/clang-based toolchain soon (see: #28238 (moved)), to be able to compile Stylo for Windows. That in turn might influence what we need to do in #28240 (moved), so we'll wait with work on the latter until the former landed. Thanks! Closing this ticket as WONTFIX then.

Trac:
Resolution: N/A to wontfix
Status: new to closed

closed

moved to tpo/applications/tor-browser#28157 (closed)