Auto merge of rust-lang#85810 - bjorn3:further_driver_cleanup, r=varkor

Driver improvements

This PR contains a couple of cleanups for the driver and a few small improvements for the custom codegen backend interface. It also implements `--version` and `-Cpasses=list` support for custom codegen backends.

Author: bors

src/driver/aot.rs

@@ -177,21 +177,6 @@ pub(crate) fn run_aot(
     metadata: EncodedMetadata,
     need_metadata_module: bool,
 ) -> Box<(CodegenResults, FxHashMap<WorkProductId, WorkProduct>)> {
-    use rustc_span::symbol::sym;
-
-    let crate_attrs = tcx.hir().attrs(rustc_hir::CRATE_HIR_ID);
-    let subsystem = tcx.sess.first_attr_value_str_by_name(crate_attrs, sym::windows_subsystem);
-    let windows_subsystem = subsystem.map(|subsystem| {
-        if subsystem != sym::windows && subsystem != sym::console {
-            tcx.sess.fatal(&format!(
-                "invalid windows subsystem `{}`, only \
-                                    `windows` and `console` are allowed",
-                subsystem
-            ));
-        }
-        subsystem.to_string()
-    });
-
     let mut work_products = FxHashMap::default();
 
     let cgus = if tcx.sess.opts.output_types.should_codegen() {
@@ -307,12 +292,10 @@ pub(crate) fn run_aot(
 
     Box::new((
         CodegenResults {
-            crate_name: tcx.crate_name(LOCAL_CRATE),
             modules,
             allocator_module,
             metadata_module,
             metadata,
-            windows_subsystem,
             linker_info: LinkerInfo::new(tcx, crate::target_triple(tcx.sess).to_string()),
             crate_info: CrateInfo::new(tcx),
         },

src/lib.rs

@@ -28,8 +28,7 @@ use rustc_codegen_ssa::traits::CodegenBackend;
 use rustc_codegen_ssa::CodegenResults;
 use rustc_errors::ErrorReported;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
-use rustc_middle::middle::cstore::{EncodedMetadata, MetadataLoader};
-use rustc_middle::ty::query::Providers;
+use rustc_middle::middle::cstore::EncodedMetadata;
 use rustc_session::config::OutputFilenames;
 use rustc_session::Session;
 
@@ -164,17 +163,14 @@ impl CodegenBackend for CraneliftCodegenBackend {
         }
     }
 
-    fn metadata_loader(&self) -> Box<dyn MetadataLoader + Sync> {
-        Box::new(rustc_codegen_ssa::back::metadata::DefaultMetadataLoader)
-    }
-
-    fn provide(&self, _providers: &mut Providers) {}
-    fn provide_extern(&self, _providers: &mut Providers) {}
-
     fn target_features(&self, _sess: &Session) -> Vec<rustc_span::Symbol> {
         vec![]
     }
 
+    fn print_version(&self) {
+        println!("Cranelift version: {}", cranelift_codegen::VERSION);
+    }
+
     fn codegen_crate(
         &self,
         tcx: TyCtxt<'_>,
@@ -222,7 +218,7 @@ impl CodegenBackend for CraneliftCodegenBackend {
             sess,
             &codegen_results,
             outputs,
-            &codegen_results.crate_name.as_str(),
+            &codegen_results.crate_info.local_crate_name.as_str(),
         );
 
         Ok(())