Function dx12_compiler 

pub fn dx12_compiler(env: Option<&str>) -> Dx12Compiler

The DX12 shader compiler: FXC (d3dcompiler_47.dll, part of Windows) unless WGPU_DX12_COMPILER (wgpu, wgpu’s own variable: fxc, dxc, auto…) names another.

Issue #471: wgpu’s default (Auto) loads whichever dxcompiler.dll the DLL search path finds first. An app ships none, so it is some other program’s (an SDK’s, a folder on PATH). A copy without its dxil.dll beside it warns that the DXIL is unsigned; wgpu takes the warning for a compile error, its own validation pipelines fail, the device is lost and the window never opens. FXC is always there and compiles what the apps’ shaders need.