feat: spirv-builder takes an optional path to locate rustc_codegen_spirv

Author: schell

crates/spirv-builder/src/lib.rs

@@ -301,6 +301,8 @@ pub struct SpirvBuilder {
  capabilities: Vec<Capability>,
  extensions: Vec<String>,
  extra_args: Vec<String>,
+ // Optional location of a known `rustc_codegen_spirv` dylib
+ rustc_codegen_spirv_location: Option<std::path::PathBuf>,
 
  // `rustc_codegen_spirv::linker` codegen args
  pub shader_panic_strategy: ShaderPanicStrategy,
@@ -330,6 +332,7 @@ impl SpirvBuilder {
  capabilities: Vec::new(),
  extensions: Vec::new(),
  extra_args: Vec::new(),
+ rustc_codegen_spirv_location: None,
 
  shader_panic_strategy: ShaderPanicStrategy::SilentExit,
 
@@ -482,6 +485,21 @@ impl SpirvBuilder {
  self
  }
 
+ #[must_use]
+ pub fn rustc_codegen_spirv_location(
+ mut self,
+ path_to_dylib: impl AsRef<std::path::Path>,
+ ) -> Self {
+ let path_to_dylib = path_to_dylib.as_ref().to_path_buf();
+ assert!(
+ path_to_dylib.is_file(),
+ "Provided path to dylib '{}' is not a file",
+ path_to_dylib.display()
+ );
+ self.rustc_codegen_spirv_location = Some(path_to_dylib);
+ self
+ }
+
  /// Builds the module. If `print_metadata` is [`MetadataPrintout::Full`], you usually don't have to inspect the path
  /// in the result, as the environment variable for the path to the module will already be set.
  pub fn build(mut self) -> Result<CompileResult, SpirvBuilderError> {
@@ -624,7 +642,10 @@ fn invoke_rustc(builder: &SpirvBuilder) -> Result<PathBuf, SpirvBuilderError> {
  // alongside build.rs, and cargo will helpfully add it to LD_LIBRARY_PATH for us! However,
  // rustc expects a full path, instead of a filename looked up via LD_LIBRARY_PATH, so we need
  // to copy cargo's understanding of library lookup and find the library and its full path.
- let rustc_codegen_spirv = find_rustc_codegen_spirv();
+ let rustc_codegen_spirv = builder
+ .rustc_codegen_spirv_location
+ .clone()
+ .unwrap_or_else(find_rustc_codegen_spirv);
 
  let mut rustflags = vec![
  format!("-Zcodegen-backend={}", rustc_codegen_spirv.display()),