Building for target on Windows causes compiler_builtins to fail: cannot find path for directory.

[XAMPPRocky]

Caught by CI, it seems that when building for a specific target on Windows compiler_builtins fails with the below error. This only happens on Windows, macOS and Linux compile successfully.

Steps to reproduce

• Be on Windows, and the Android SDK installed.
• Clone rust-gpu
• cargo install cargo-apk
• rustup target add aarch64-linux-android
• cargo apk build --manifest-path examples/runners/wgpu/Cargo.toml

      Finished dev [unoptimized + debuginfo] target(s) in 0.14s
      Updating crates.io index
     Compiling compiler_builtins v0.1.36
     Compiling core v0.0.0 (C:\Rust\.rustup\toolchains\nightly-2020-11-15-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core)
  error: failed to remove D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\release\build\compiler_builtins-62b8451d4c2cb3da\build_script_build-62b8451d4c2cb3da.build_script_build.48a9juya-cgu.0.rcgu.o: The system cannot find the path specified. (os error 3)

  error: failed to remove D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\release\build\compiler_builtins-62b8451d4c2cb3da\build_script_build-62b8451d4c2cb3da.build_script_build.48a9juya-cgu.1.rcgu.o: The system cannot find the path specified. (os error 3)

  error: failed to remove D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\release\build\compiler_builtins-62b8451d4c2cb3da\build_script_build-62b8451d4c2cb3da.build_script_build.48a9juya-cgu.10.rcgu.o: The system cannot find the path specified. (os error 3)

  error: failed to remove D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\release\build\compiler_builtins-62b8451d4c2cb3da\build_script_build-62b8451d4c2cb3da.build_script_build.48a9juya-cgu.11.rcgu.o: The system cannot find the path specified. (os error 3)

  error: failed to remove D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\release\build\compiler_builtins-62b8451d4c2cb3da\build_script_build-62b8451d4c2cb3da.build_script_build.48a9juya-cgu.12.rcgu.o: The system cannot find the path specified. (os error 3)

  error: failed to remove D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\release\build\compiler_builtins-62b8451d4c2cb3da\build_script_build-62b8451d4c2cb3da.build_script_build.48a9juya-cgu.13.rcgu.o: The system cannot find the path specified. (os error 3)

  error: failed to remove D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\release\build\compiler_builtins-62b8451d4c2cb3da\build_script_build-62b8451d4c2cb3da.build_script_build.48a9juya-cgu.14.rcgu.o: The system cannot find the path specified. (os error 3)

  error: failed to remove D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\release\build\compiler_builtins-62b8451d4c2cb3da\build_script_build-62b8451d4c2cb3da.build_script_build.48a9juya-cgu.15.rcgu.o: The system cannot find the path specified. (os error 3)

  error: failed to remove D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\release\build\compiler_builtins-62b8451d4c2cb3da\build_script_build-62b8451d4c2cb3da.build_script_build.48a9juya-cgu.2.rcgu.o: The system cannot find the path specified. (os error 3)

  error: failed to remove D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\release\build\compiler_builtins-62b8451d4c2cb3da\build_script_build-62b8451d4c2cb3da.build_script_build.48a9juya-cgu.3.rcgu.o: The system cannot find the path specified. (os error 3)

  error: failed to remove D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\release\build\compiler_builtins-62b8451d4c2cb3da\build_script_build-62b8451d4c2cb3da.build_script_build.48a9juya-cgu.4.rcgu.o: The system cannot find the path specified. (os error 3)

  error: failed to remove D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\release\build\compiler_builtins-62b8451d4c2cb3da\build_script_build-62b8451d4c2cb3da.build_script_build.48a9juya-cgu.5.rcgu.o: The system cannot find the path specified. (os error 3)

  error: failed to remove D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\release\build\compiler_builtins-62b8451d4c2cb3da\build_script_build-62b8451d4c2cb3da.build_script_build.48a9juya-cgu.6.rcgu.o: The system cannot find the path specified. (os error 3)

  error: failed to remove D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\release\build\compiler_builtins-62b8451d4c2cb3da\build_script_build-62b8451d4c2cb3da.build_script_build.48a9juya-cgu.7.rcgu.o: The system cannot find the path specified. (os error 3)

  error: failed to remove D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\release\build\compiler_builtins-62b8451d4c2cb3da\build_script_build-62b8451d4c2cb3da.build_script_build.48a9juya-cgu.8.rcgu.o: The system cannot find the path specified. (os error 3)

  error: failed to remove D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\release\build\compiler_builtins-62b8451d4c2cb3da\build_script_build-62b8451d4c2cb3da.build_script_build.48a9juya-cgu.9.rcgu.o: The system cannot find the path specified. (os error 3)

  error: aborting due to 16 previous errors

  error: failed to write `D:\a\rust-gpu\rust-gpu\examples\runners\wgpu\target\aarch64-linux-android\debug\build\example-runner-wgpu-8d75f3772af0d1f4\out\sysroot\target\spirv-unknown-unknown\release\.fingerprint\compiler_builtins-bbe7f7415176f8bb\run-build-script-build-script-build.json`

  Caused by:
    The system cannot find the path specified. (os error 3)
  warning: build failed, waiting for other jobs to finish...
  error: build failed

https://github.com/EmbarkStudios/rust-gpu/pull/239/checks?check_run_id=1453705992#step:12:222

[DianaNites]

I don't use windows so will be unable to reproduce, but i'll look into it right now. Could be related to rust-lang/rust#29497

[XAMPPRocky]

Closing, as I've traced the issue down to cargo not supporting long paths on Windows, os it's not a problem with cargo-sysroot. There's a PR to fix it rust-lang/cargo#8874