Make CodegenBackend::join_codegen infallible.

Because they all are, in practice.

Author: nnethercote

compiler/rustc_codegen_cranelift/src/lib.rs

@@ -233,11 +233,11 @@ impl CodegenBackend for CraneliftCodegenBackend {
  ongoing_codegen: Box<dyn Any>,
  sess: &Session,
  _outputs: &OutputFilenames,
- ) -> Result<(CodegenResults, FxIndexMap<WorkProductId, WorkProduct>), ErrorGuaranteed> {
- Ok(ongoing_codegen
+ ) -> (CodegenResults, FxIndexMap<WorkProductId, WorkProduct>) {
+ ongoing_codegen
  .downcast::<driver::aot::OngoingCodegen>()
  .unwrap()
- .join(sess, self.config.borrow().as_ref().unwrap()))
+ .join(sess, self.config.borrow().as_ref().unwrap())
  }
 
  fn link(

compiler/rustc_codegen_gcc/src/lib.rs

@@ -217,13 +217,11 @@ impl CodegenBackend for GccCodegenBackend {
  Box::new(res)
  }
 
- fn join_codegen(&self, ongoing_codegen: Box<dyn Any>, sess: &Session, _outputs: &OutputFilenames) -> Result<(CodegenResults, FxIndexMap<WorkProductId, WorkProduct>), ErrorGuaranteed> {
- let (codegen_results, work_products) = ongoing_codegen
+ fn join_codegen(&self, ongoing_codegen: Box<dyn Any>, sess: &Session, _outputs: &OutputFilenames) -> (CodegenResults, FxIndexMap<WorkProductId, WorkProduct>) {
+ ongoing_codegen
  .downcast::<rustc_codegen_ssa::back::write::OngoingCodegen<GccCodegenBackend>>()
  .expect("Expected GccCodegenBackend's OngoingCodegen, found Box<Any>")
- .join(sess);
-
- Ok((codegen_results, work_products))
+ .join(sess)
  }
 
  fn link(&self, sess: &Session, codegen_results: CodegenResults, outputs: &OutputFilenames) -> Result<(), ErrorGuaranteed> {

compiler/rustc_codegen_llvm/src/lib.rs

@@ -369,7 +369,7 @@ impl CodegenBackend for LlvmCodegenBackend {
  ongoing_codegen: Box<dyn Any>,
  sess: &Session,
  outputs: &OutputFilenames,
- ) -> Result<(CodegenResults, FxIndexMap<WorkProductId, WorkProduct>), ErrorGuaranteed> {
+ ) -> (CodegenResults, FxIndexMap<WorkProductId, WorkProduct>) {
  let (codegen_results, work_products) = ongoing_codegen
  .downcast::<rustc_codegen_ssa::back::write::OngoingCodegen<LlvmCodegenBackend>>()
  .expect("Expected LlvmCodegenBackend's OngoingCodegen, found Box<Any>")
@@ -382,7 +382,7 @@ impl CodegenBackend for LlvmCodegenBackend {
  });
  }
 
- Ok((codegen_results, work_products))
+ (codegen_results, work_products)
  }
 
  fn link(

compiler/rustc_codegen_ssa/src/traits/backend.rs

@@ -102,7 +102,7 @@ pub trait CodegenBackend {
  ongoing_codegen: Box<dyn Any>,
  sess: &Session,
  outputs: &OutputFilenames,
- ) -> Result<(CodegenResults, FxIndexMap<WorkProductId, WorkProduct>), ErrorGuaranteed>;
+ ) -> (CodegenResults, FxIndexMap<WorkProductId, WorkProduct>);
 
  /// This is called on the returned `CodegenResults` from `join_codegen`
  fn link(

compiler/rustc_interface/src/queries.rs

@@ -259,7 +259,7 @@ pub struct Linker {
 impl Linker {
  pub fn link(self, sess: &Session, codegen_backend: &dyn CodegenBackend) -> Result<()> {
  let (codegen_results, work_products) =
- codegen_backend.join_codegen(self.ongoing_codegen, sess, &self.output_filenames)?;
+ codegen_backend.join_codegen(self.ongoing_codegen, sess, &self.output_filenames);
 
  sess.compile_status()?;
 

tests/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs

@@ -49,11 +49,11 @@ impl CodegenBackend for TheBackend {
  ongoing_codegen: Box<dyn Any>,
  _sess: &Session,
  _outputs: &OutputFilenames,
- ) -> Result<(CodegenResults, FxIndexMap<WorkProductId, WorkProduct>), ErrorGuaranteed> {
+ ) -> (CodegenResults, FxIndexMap<WorkProductId, WorkProduct>) {
  let codegen_results = ongoing_codegen
  .downcast::<CodegenResults>()
  .expect("in join_codegen: ongoing_codegen is not a CodegenResults");
- Ok((*codegen_results, FxIndexMap::default()))
+ (*codegen_results, FxIndexMap::default())
  }
 
  fn link(