Alter compile_{f,d}xc to take Option<&CStr>

wgpu-hal/src/dx12/device.rs

@@ -262,9 +262,7 @@ impl super::Device {
         let source_name = stage
             .module
             .raw_name
-            .as_ref()
-            .and_then(|cstr| cstr.to_str().ok())
-            .unwrap_or_default();
+            .as_deref();
 
         // Compile with DXC if available, otherwise fall back to FXC
         let (result, log_level) = if let Some(ref dxc_container) = self.dxc_container {

wgpu-hal/src/dx12/shader_compilation.rs

@@ -14,7 +14,7 @@ use crate::auxil::dxgi::result::HResult;
 pub(super) fn compile_fxc(
     device: &super::Device,
     source: &str,
-    source_name: &str,
+    source_name: Option<&CStr>,
     raw_ep: &std::ffi::CString,
     stage_bit: wgt::ShaderStages,
     full_stage: String,
@@ -34,11 +34,7 @@ pub(super) fn compile_fxc(
     }
 
     // If no name has been set, D3DCompile wants the null pointer.
-    let source_name = if source_name.is_empty() {
-        ptr::null()
-    } else {
-        source_name.as_ptr()
-    };
+    let source_name = source_name.map(|cstr| cstr.as_ptr()).unwrap_or(ptr::null());
 
     let mut error = d3d12::Blob::null();
     let hr = unsafe {
@@ -140,7 +136,7 @@ mod dxc {
     pub(crate) fn compile_dxc(
         device: &crate::dx12::Device,
         source: &str,
-        source_name: &str,
+        source_name: Option<&CStr>,
         raw_ep: &str,
         stage_bit: wgt::ShaderStages,
         full_stage: String,
@@ -174,6 +170,8 @@ mod dxc {
             Err(e) => return (Err(e), log::Level::Error),
         };
 
+        let source_name = source_name.map(|cstr| cstr.to_str()).unwrap_or(&"");
+
         let compiled = dxc_container.compiler.compile(
             &blob,
             source_name,