[Bug]: x86 build on windows fails if the crate uses proc-macro

[sevenc-nanashi]

Current Behavior

If the crate uses proc-macro, it becomes impossible to do cross-compile for x86-windows on windows.

Expected Behavior

It should success.

Steps To Reproduce

1. Use some proc-macro crate (Minimum reproduction: https://github.com/sevenc-nanashi/corrosion-x86-min-repro , this uses const_random crate)
2. cmake -S . -B "build" -A Win32 && cmake --build build

Environment

- OS: Windows 10
- CMake: cmake version 3.31.3
- CMake Generator: Visual Studio 17 2022 / Win32

CMake configure log with Debug log-level

-- Selecting Windows SDK version 10.0.22000.0 to target Windows 10.0.19045.
-- Using Corrosion 0.99.99 with CMake 3.31.3 and the `Visual Studio 17 2022` Generator
-- Rust Toolchain: stable-x86_64-pc-windows-msvc
-- Rust toolchain stable-x86_64-pc-windows-msvc
-- Rust toolchain path C:\Users\katama\.rustup\toolchains\stable-x86_64-pc-windows-msvc
-- Rust Target: i686-pc-windows-msvc
-- Cargo target  is an official target-triple
-- Installed targets: i686-pc-windows-msvc;x86_64-pc-windows-msvc
-- Parsed Target triple: arch: i686, vendor: pc, OS: windows, env: msvc
-- Parsed Target triple: arch: x86_64, vendor: pc, OS: windows, env: msvc
-- Found 1 targets in package rust-lib
-- TARGET rust_lib produces byproducts rust_lib.lib
-- Corrosion created the following CMake targets: rust_lib
-- Output directory property (target rust_lib): ARCHIVE_OUTPUT_DIRECTORY dir: output_directory-NOTFOUND
-- Setting IMPORTED_LOCATION_DEBUG for target rust_lib-static to `E:/corrosion-x86-min-repro/build/rust_lib.lib`.
-- Setting IMPORTED_LOCATION_RELEASE for target rust_lib-static to `E:/corrosion-x86-min-repro/build/rust_lib.lib`.
-- Setting IMPORTED_LOCATION_MINSIZEREL for target rust_lib-static to `E:/corrosion-x86-min-repro/build/rust_lib.lib`.
-- Setting IMPORTED_LOCATION_RELWITHDEBINFO for target rust_lib-static to `E:/corrosion-x86-min-repro/build/rust_lib.lib`.
-- Setting IMPORTED_LOCATION for target rust_lib-static to `E:/corrosion-x86-min-repro/build/rust_lib.lib`.
-- Adding command to copy byproducts `rust_lib.lib` to $<$<CONFIG:Debug>:E:/corrosion-x86-min-repro/build>$<$<CONFIG:Release>:E:/corrosion-x86-min-repro/build>$<$<CONFIG:MinSizeRel>:E:/corrosion-x86-min-repro/build>$<$<CONFIG:RelWithDebInfo>:E:/corrosion-x86-min-repro/build>/rust_lib.lib
-- Configuring done (0.6s)
-- Generating done (0.2s)
-- Build files have been written to: E:/corrosion-x86-min-repro/build

CMake Build step log

__gi_build.log

[sevenc-nanashi]

I found that this is caused by environment variable named VSTEL_MSBuildProjectFullPath, and adding --unset=VSTEL_MSBuildProjectFullPath on

corrosion/cmake/Corrosion.cmake

Line 815 in 999f93b

"${build_env_variable_genex}"

solves the issue.
But I don't know if it's okay to unset this variable...

[jschwe]

Which rust version are you using? Does it only occur with Rust 1.83 or can you also reproduce with Rust 1.82?

[sevenc-nanashi]

I used 1.83.0 to reproduce the issue.
I did rustup override set 1.82.0, and the error was gone.

[jschwe]

Could you also check if the issue is still present in the latest nightly or the beta toolchain?
It looks like rust-lang/rust#134505 fixes rust-lang/rust#133794, which looks similar to this issue.
If the issue is fixed in Rust 1.84 already, then I would prefer to not add any workarounds to corrosion just for one specific Rust version.

[sevenc-nanashi]

Looks like it's not fixed yet in nightly.

cmake -S . -B "build" -A Win32 -D Rust_RUSTUP_INSTALL_MISSING_TARGET=ON && cmake --build build | tee __gi_build_nightly.log
__gi_build_nightly.log

Oops, I haven't updated my nightly...

[sevenc-nanashi]

It was fixed on nightly! I'm closing the PR.