Can't build libz-ng-sys on i686-pc-windows-msvc

Building fails with an error getting the `VCTargetsPath`

On a 32-bit x86 Windows 10 system (build 19041.vb_release.191206-1406), where Rust is using the Visual C++ Build tools (rustup toolchain stable-i686-pc-windows-msvc), attempting commands such as cargo build or cargo test in any projects that use libz-ng-sys fails with the error:

  CMake Error at CMakeLists.txt:35 (project):
    Failed to run MSBuild command:

      C:/Program Files/Microsoft Visual Studio/2022/BuildTools/MSBuild/Current/Bin/amd64/MSBuild.exe

    to get the value of VCTargetsPath:

      unknown error

The amd64 part looks wrong, since this is not cross-compilation and this is a 32-bit system. That directory does exist, but it seems odd that it would be used here and perhaps that is relevant.

Discovery and relationship to gitoxide

I originally had this problem when attempting to build or install gitoxide. It happens both with cargo install gitoxide and with commands like cargo build invoked in the cloned gitoxide repository directory. The problem appears specific to libz-ng-sys, though I am unsure if the problem is in this Rust create or in the underlying native library.

Running cargo install gitoxide --no-default-features --features max-pure allows the build to succeed by not depending on libz-ng-sys.
Running cargo build --release --no-default-features --features max-control,gix-features/zlib-stock,gitoxide-core-blocking-client,http-client-curl, which is documented to have the same effect as the default max feature except to use "the stock zlib library instead of zlib-ng," likewise succeeds.

Why this is not specific to gitoxide

I don't think the bug--assuming this is a bug, rather than a configuration problem that I may not properly understand--is in gitoxide, since this always happens with libz-ng-sys. Here's a simpler example, in a project that doesn't have anything else going on besides its libz-ng-sys dependency:

PS C:\Users\ek\repos> cargo new try-libz-ng-sys
    Creating binary (application) `try-libz-ng-sys` package
note: see more `Cargo.toml` keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
PS C:\Users\ek\repos> cd .\try-libz-ng-sys\
PS C:\Users\ek\repos\try-libz-ng-sys> cargo add libz-ng-sys
    Updating crates.io index
      Adding libz-ng-sys v1.1.15 to dependencies
    Updating crates.io index
     Locking 5 packages to latest compatible versions
PS C:\Users\ek\repos\try-libz-ng-sys> cargo build
  Downloaded cmake v0.1.50
  Downloaded cc v1.0.102
  Downloaded libc v0.2.155
  Downloaded libz-ng-sys v1.1.15
  Downloaded 4 crates (3.2 MB) in 3.16s (largest was `libz-ng-sys` at 2.4 MB)
   Compiling cc v1.0.102
   Compiling libc v0.2.155
   Compiling cmake v0.1.50
   Compiling libz-ng-sys v1.1.15
error: failed to run custom build command for `libz-ng-sys v1.1.15`

Caused by:
  process didn't exit successfully: `C:\Users\ek\repos\try-libz-ng-sys\target\debug\build\libz-ng-sys-80a5fec7b53b81c4\build-script-build_zng` (exit code: 101)
  --- stdout
  CMAKE_TOOLCHAIN_FILE_i686-pc-windows-msvc = None
  CMAKE_TOOLCHAIN_FILE_i686_pc_windows_msvc = None
  HOST_CMAKE_TOOLCHAIN_FILE = None
  CMAKE_TOOLCHAIN_FILE = None
  CMAKE_GENERATOR_i686-pc-windows-msvc = None
  CMAKE_GENERATOR_i686_pc_windows_msvc = None
  HOST_CMAKE_GENERATOR = None
  CMAKE_GENERATOR = None
  CMAKE_PREFIX_PATH_i686-pc-windows-msvc = None
  CMAKE_PREFIX_PATH_i686_pc_windows_msvc = None
  HOST_CMAKE_PREFIX_PATH = None
  CMAKE_PREFIX_PATH = None
  CMAKE_i686-pc-windows-msvc = None
  CMAKE_i686_pc_windows_msvc = None
  HOST_CMAKE = None
  CMAKE = None
  running: "cmake" "C:\\Users\\ek\\.cargo\\registry\\src\\index.crates.io-1cd66030c949c28d\\libz-ng-sys-1.1.15\\src/zlib-ng" "-G" "Visual Studio 17 2022" "-Thost=x86" "-AWin32" "-DBUILD_SHARED_LIBS=OFF" "-DZLIB_COMPAT=OFF" "-DZLIB_ENABLE_TESTS=OFF" "-DWITH_GZFILEOP=ON" "-DCMAKE_GENERATOR_PLATFORM=Win32" "-DCMAKE_INSTALL_PREFIX=C:\\Users\\ek\\repos\\try-libz-ng-sys\\target\\debug\\build\\libz-ng-sys-f444bf96aef349e8\\out" "-DCMAKE_C_FLAGS= -nologo -MD -Brepro" "-DCMAKE_C_FLAGS_DEBUG= -nologo -MD -Brepro" "-DCMAKE_CXX_FLAGS= -nologo -MD -Brepro" "-DCMAKE_CXX_FLAGS_DEBUG= -nologo -MD -Brepro" "-DCMAKE_ASM_FLAGS= -nologo -MD -Brepro" "-DCMAKE_ASM_FLAGS_DEBUG= -nologo -MD -Brepro" "-DCMAKE_BUILD_TYPE=Debug"
  -- Using CMake version 3.29.6
  -- ZLIB_HEADER_VERSION: 1.3.0
  -- ZLIBNG_HEADER_VERSION: 2.1.6
  -- Selecting Windows SDK version 10.0.20348.0 to target Windows 10.0.19045.
  -- Configuring incomplete, errors occurred!

  --- stderr
  CMake Error at CMakeLists.txt:35 (project):
    Failed to run MSBuild command:

      C:/Program Files/Microsoft Visual Studio/2022/BuildTools/MSBuild/Current/Bin/amd64/MSBuild.exe

    to get the value of VCTargetsPath:

      unknown error

  thread 'main' panicked at C:\Users\ek\.cargo\registry\src\index.crates.io-1cd66030c949c28d\cmake-0.1.50\src\lib.rs:1098:5:

  command did not execute successfully, got: exit code: 1

  build script failed, must exit now
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Why this is probably not related to the `cmake` crate code

I don't believe the problem is in cmake-rs. Setting environment variables to get a readable backtrace and repeating the build gives:

PS C:\Users\ek\repos\try-libz-ng-sys> $env:RUST_BACKTRACE = '1'
PS C:\Users\ek\repos\try-libz-ng-sys> $env:CARGO_PROFILE_DEV_BUILD_OVERRIDE_DEBUG = 'true'
PS C:\Users\ek\repos\try-libz-ng-sys> cargo build
   Compiling cc v1.0.102
   Compiling libc v0.2.155
   Compiling cmake v0.1.50
   Compiling libz-ng-sys v1.1.15
error: failed to run custom build command for `libz-ng-sys v1.1.15`

Caused by:
  process didn't exit successfully: `C:\Users\ek\repos\try-libz-ng-sys\target\debug\build\libz-ng-sys-c8c2e254c3f755b6\build-script-build_zng` (exit code: 101)
  --- stdout
  CMAKE_TOOLCHAIN_FILE_i686-pc-windows-msvc = None
  CMAKE_TOOLCHAIN_FILE_i686_pc_windows_msvc = None
  HOST_CMAKE_TOOLCHAIN_FILE = None
  CMAKE_TOOLCHAIN_FILE = None
  CMAKE_GENERATOR_i686-pc-windows-msvc = None
  CMAKE_GENERATOR_i686_pc_windows_msvc = None
  HOST_CMAKE_GENERATOR = None
  CMAKE_GENERATOR = None
  CMAKE_PREFIX_PATH_i686-pc-windows-msvc = None
  CMAKE_PREFIX_PATH_i686_pc_windows_msvc = None
  HOST_CMAKE_PREFIX_PATH = None
  CMAKE_PREFIX_PATH = None
  CMAKE_i686-pc-windows-msvc = None
  CMAKE_i686_pc_windows_msvc = None
  HOST_CMAKE = None
  CMAKE = None
  running: "cmake" "C:\\Users\\ek\\.cargo\\registry\\src\\index.crates.io-1cd66030c949c28d\\libz-ng-sys-1.1.15\\src/zlib-ng" "-G" "Visual Studio 17 2022" "-Thost=x86" "-AWin32" "-DBUILD_SHARED_LIBS=OFF" "-DZLIB_COMPAT=OFF" "-DZLIB_ENABLE_TESTS=OFF" "-DWITH_GZFILEOP=ON" "-DCMAKE_GENERATOR_PLATFORM=Win32" "-DCMAKE_INSTALL_PREFIX=C:\\Users\\ek\\repos\\try-libz-ng-sys\\target\\debug\\build\\libz-ng-sys-4f8f5509e9e4f77a\\out" "-DCMAKE_C_FLAGS= -nologo -MD -Brepro" "-DCMAKE_C_FLAGS_DEBUG= -nologo -MD -Brepro" "-DCMAKE_CXX_FLAGS= -nologo -MD -Brepro" "-DCMAKE_CXX_FLAGS_DEBUG= -nologo -MD -Brepro" "-DCMAKE_ASM_FLAGS= -nologo -MD -Brepro" "-DCMAKE_ASM_FLAGS_DEBUG= -nologo -MD -Brepro" "-DCMAKE_BUILD_TYPE=Debug"
  -- Using CMake version 3.29.6
  -- ZLIB_HEADER_VERSION: 1.3.0
  -- ZLIBNG_HEADER_VERSION: 2.1.6
  -- Selecting Windows SDK version 10.0.20348.0 to target Windows 10.0.19045.
  -- Configuring incomplete, errors occurred!

  --- stderr
  CMake Error at CMakeLists.txt:35 (project):
    Failed to run MSBuild command:

      C:/Program Files/Microsoft Visual Studio/2022/BuildTools/MSBuild/Current/Bin/amd64/MSBuild.exe

    to get the value of VCTargetsPath:

      unknown error

  thread 'main' panicked at C:\Users\ek\.cargo\registry\src\index.crates.io-1cd66030c949c28d\cmake-0.1.50\src\lib.rs:1098:5:

  command did not execute successfully, got: exit code: 1

  build script failed, must exit now
  stack backtrace:
     0: std::panicking::begin_panic_handler
               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library\std\src\panicking.rs:652
     1: core::panicking::panic_fmt
               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library\core\src\panicking.rs:72
     2: cmake::fail
               at C:\Users\ek\.cargo\registry\src\index.crates.io-1cd66030c949c28d\cmake-0.1.50\src\lib.rs:1098
     3: alloc::alloc::realloc
               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library\alloc\src\alloc.rs:138
     4: alloc::alloc::Global::grow_impl
               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library\alloc\src\alloc.rs:215
     5: alloc::alloc::impl$1::grow
               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library\alloc\src\alloc.rs:268
     6: alloc::raw_vec::finish_grow<alloc::alloc::Global>
               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library\alloc\src\raw_vec.rs:570
     7: cmake::Config::build
               at C:\Users\ek\.cargo\registry\src\index.crates.io-1cd66030c949c28d\cmake-0.1.50\src\lib.rs:813
     8: build_script_build_zng::build_zlib_ng
               at .\build_zng.rs:21
     9: build_script_build_zng::main
               at .\build_zng.rs:59
    10: core::ops::function::FnOnce::call_once<void (*)(),tuple$<> >
               at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081\library\core\src\ops\function.rs:250
  note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

The reference to cmake-rs code, other than its fail function, is to this invocation of the cmake command:

run(cmd.env("CMAKE_PREFIX_PATH", cmake_prefix_path), "cmake");

So that's just the cmake external command failing.

The system has a working `cmake` command

I don't think the problem is with cmake itself. It is installed and otherwise working:

PS C:\Users\ek\repos\try-libz-ng-sys> cmake --version
cmake version 3.29.6

CMake suite maintained and supported by Kitware (kitware.com/cmake).

Toolchain and environment variations tested

Because Visual Studio 2022 does not support 32-bit systems, I obtained the needed MSVC toolchain by installing the Visual Studio C++ build tools, which is also an approach listed in the Getting started instructions for Rust on Windows. Specifically, I installed the Visual Studio Build Tools 2022, version 17.10.3, selecting "Desktop development with C++."

Originally I went with the default selections, which included "Windows 11 SDK (10.0.22621.0)" and no other Windows SDKs. The build attempted to use this SDK. But it is a Windows 11 SDK, on a Windows 10 system. Just in case that was the problem, I uninstalled all Rust tools with rustup, verified that my .cargo directory was deleted, uninstalled that Windows 11 SDK, and installed all four of the Windows 10 SDKs instead (10.0.20348.0, 10.0.19041.0, and 10.0.18362.0) in the Visual Studio Installer, and then bootstrapped rustup again and started over. The above output is all from after doing that.
Although I would not expect cargo commands to require binaries provided by those build tools to be in the PATH (and other builds, including e.g. those that use curl-sys, are working), I have repeated the above from the Developer PowerShell for VS 2022, which has them. This gave the same result. I did this both times, with the default build tools installation that had a Windows 11 SDK, and after modifying that installation to have no Windows 11 SDKs and all available Windows 10 SDKs.

rust-lang / libz-sys