Auto merge of #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.

13 files changed, 103 insertions, 135 deletions

diff --git a/compiler/rustc_codegen_cranelift/src/driver/aot.rs b/compiler/rustc_codegen_cranelift/src/driver/aot.rs
index 9cf51d15c8c..6676d88602c 100644
--- a/compiler/rustc_codegen_cranelift/src/driver/aot.rs
+++ b/compiler/rustc_codegen_cranelift/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),
         },
diff --git a/compiler/rustc_codegen_cranelift/src/lib.rs b/compiler/rustc_codegen_cranelift/src/lib.rs
index 4ee887cd5af..904efed5bd9 100644
--- a/compiler/rustc_codegen_cranelift/src/lib.rs
+++ b/compiler/rustc_codegen_cranelift/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(())
diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
index 728f1224dd8..776cb2ee99b 100644
--- a/compiler/rustc_codegen_llvm/src/lib.rs
+++ b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -29,8 +29,8 @@ use rustc_codegen_ssa::{CodegenResults, CompiledModule};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::{ErrorReported, FatalError, Handler};
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
-use rustc_middle::middle::cstore::{EncodedMetadata, MetadataLoaderDyn};
-use rustc_middle::ty::{self, TyCtxt};
+use rustc_middle::middle::cstore::EncodedMetadata;
+use rustc_middle::ty::TyCtxt;
 use rustc_session::config::{OptLevel, OutputFilenames, PrintRequest};
 use rustc_session::Session;
 use rustc_span::symbol::Symbol;
@@ -248,13 +248,6 @@ impl CodegenBackend for LlvmCodegenBackend {
         target_features(sess)
     }
 
-    fn metadata_loader(&self) -> Box<MetadataLoaderDyn> {
-        Box::new(rustc_codegen_ssa::back::metadata::DefaultMetadataLoader)
-    }
-
-    fn provide(&self, _providers: &mut ty::query::Providers) {}
-    fn provide_extern(&self, _providers: &mut ty::query::Providers) {}
-
     fn codegen_crate<'tcx>(
         &self,
         tcx: TyCtxt<'tcx>,
@@ -304,7 +297,7 @@ impl CodegenBackend for LlvmCodegenBackend {
             sess,
             &codegen_results,
             outputs,
-            &codegen_results.crate_name.as_str(),
+            &codegen_results.crate_info.local_crate_name.as_str(),
         );
 
         Ok(())
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index f9f59be1e8b..05df7ab5388 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -1957,7 +1957,7 @@ fn add_order_independent_options(
     cmd.output_filename(out_filename);
 
     if crate_type == CrateType::Executable && sess.target.is_like_windows {
-        if let Some(ref s) = codegen_results.windows_subsystem {
+        if let Some(ref s) = codegen_results.crate_info.windows_subsystem {
             cmd.subsystem(s);
         }
     }
diff --git a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
index 14d6f0ba147..b2ecc3b0f32 100644
--- a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
+++ b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
@@ -370,7 +370,6 @@ pub fn provide(providers: &mut Providers) {
 pub fn provide_extern(providers: &mut Providers) {
     providers.is_reachable_non_generic = is_reachable_non_generic_provider_extern;
     providers.upstream_monomorphizations_for = upstream_monomorphizations_for_provider;
-    providers.wasm_import_module_map = wasm_import_module_map;
 }
 
 fn symbol_export_level(tcx: TyCtxt<'_>, sym_def_id: DefId) -> SymbolExportLevel {
diff --git a/compiler/rustc_codegen_ssa/src/back/write.rs b/compiler/rustc_codegen_ssa/src/back/write.rs
index 49774dc6d5c..ff4e6409571 100644
--- a/compiler/rustc_codegen_ssa/src/back/write.rs
+++ b/compiler/rustc_codegen_ssa/src/back/write.rs
@@ -31,7 +31,7 @@ use rustc_session::config::{self, CrateType, Lto, OutputFilenames, OutputType};
 use rustc_session::config::{Passes, SwitchWithOptPath};
 use rustc_session::Session;
 use rustc_span::source_map::SourceMap;
-use rustc_span::symbol::{sym, Symbol};
+use rustc_span::symbol::sym;
 use rustc_span::{BytePos, FileName, InnerSpan, Pos, Span};
 use rustc_target::spec::{MergeFunctions, PanicStrategy, SanitizerSet};
 
@@ -426,21 +426,9 @@ pub fn start_async_codegen<B: ExtraBackendMethods>(
     let (coordinator_send, coordinator_receive) = channel();
     let sess = tcx.sess;
 
-    let crate_name = tcx.crate_name(LOCAL_CRATE);
     let crate_attrs = tcx.hir().attrs(rustc_hir::CRATE_HIR_ID);
     let no_builtins = tcx.sess.contains_name(crate_attrs, sym::no_builtins);
     let is_compiler_builtins = tcx.sess.contains_name(crate_attrs, sym::compiler_builtins);
-    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 linker_info = LinkerInfo::new(tcx, target_cpu);
     let crate_info = CrateInfo::new(tcx);
@@ -472,9 +460,7 @@ pub fn start_async_codegen<B: ExtraBackendMethods>(
 
     OngoingCodegen {
         backend,
-        crate_name,
         metadata,
-        windows_subsystem,
         linker_info,
         crate_info,
 
@@ -1812,9 +1798,7 @@ impl SharedEmitterMain {
 
 pub struct OngoingCodegen<B: ExtraBackendMethods> {
     pub backend: B,
-    pub crate_name: Symbol,
     pub metadata: EncodedMetadata,
-    pub windows_subsystem: Option<String>,
     pub linker_info: LinkerInfo,
     pub crate_info: CrateInfo,
     pub coordinator_send: Sender<Box<dyn Any + Send>>,
@@ -1857,9 +1841,7 @@ impl<B: ExtraBackendMethods> OngoingCodegen<B> {
 
         (
             CodegenResults {
-                crate_name: self.crate_name,
                 metadata: self.metadata,
-                windows_subsystem: self.windows_subsystem,
                 linker_info: self.linker_info,
                 crate_info: self.crate_info,
 
diff --git a/compiler/rustc_codegen_ssa/src/base.rs b/compiler/rustc_codegen_ssa/src/base.rs
index b44e74d5ae8..38ab39febe0 100644
--- a/compiler/rustc_codegen_ssa/src/base.rs
+++ b/compiler/rustc_codegen_ssa/src/base.rs
@@ -30,6 +30,7 @@ use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
 use rustc_session::cgu_reuse_tracker::CguReuse;
 use rustc_session::config::{self, EntryFnType};
 use rustc_session::Session;
+use rustc_span::symbol::sym;
 use rustc_target::abi::{Align, LayoutOf, VariantIdx};
 
 use std::ops::{Deref, DerefMut};
@@ -755,7 +756,22 @@ impl<B: ExtraBackendMethods> Drop for AbortCodegenOnDrop<B> {
 
 impl CrateInfo {
     pub fn new(tcx: TyCtxt<'_>) -> CrateInfo {
+        let local_crate_name = tcx.crate_name(LOCAL_CRATE);
+        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 info = CrateInfo {
+            local_crate_name,
             panic_runtime: None,
             compiler_builtins: None,
             profiler_runtime: None,
@@ -769,6 +785,7 @@ impl CrateInfo {
             lang_item_to_crate: Default::default(),
             missing_lang_items: Default::default(),
             dependency_formats: tcx.dependency_formats(()),
+            windows_subsystem,
         };
         let lang_items = tcx.lang_items();
 
diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs
index 48171ccd2fd..b6de12fa35e 100644
--- a/compiler/rustc_codegen_ssa/src/lib.rs
+++ b/compiler/rustc_codegen_ssa/src/lib.rs
@@ -135,6 +135,7 @@ impl From<&cstore::NativeLib> for NativeLib {
 /// and the corresponding properties without referencing information outside of a `CrateInfo`.
 #[derive(Debug, Encodable, Decodable)]
 pub struct CrateInfo {
+    pub local_crate_name: Symbol,
     pub panic_runtime: Option<CrateNum>,
     pub compiler_builtins: Option<CrateNum>,
     pub profiler_runtime: Option<CrateNum>,
@@ -148,16 +149,15 @@ pub struct CrateInfo {
     pub lang_item_to_crate: FxHashMap<LangItem, CrateNum>,
     pub missing_lang_items: FxHashMap<CrateNum, Vec<LangItem>>,
     pub dependency_formats: Lrc<Dependencies>,
+    pub windows_subsystem: Option<String>,
 }
 
 #[derive(Encodable, Decodable)]
 pub struct CodegenResults {
-    pub crate_name: Symbol,
     pub modules: Vec<CompiledModule>,
     pub allocator_module: Option<CompiledModule>,
     pub metadata_module: Option<CompiledModule>,
     pub metadata: rustc_middle::middle::cstore::EncodedMetadata,
-    pub windows_subsystem: Option<String>,
     pub linker_info: back::linker::LinkerInfo,
     pub crate_info: CrateInfo,
 }
diff --git a/compiler/rustc_codegen_ssa/src/traits/backend.rs b/compiler/rustc_codegen_ssa/src/traits/backend.rs
index f28db2fe84b..dc4146ec7b5 100644
--- a/compiler/rustc_codegen_ssa/src/traits/backend.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/backend.rs
@@ -63,9 +63,16 @@ pub trait CodegenBackend {
         None
     }
 
-    fn metadata_loader(&self) -> Box<MetadataLoaderDyn>;
-    fn provide(&self, _providers: &mut Providers);
-    fn provide_extern(&self, _providers: &mut Providers);
+    /// The metadata loader used to load rlib and dylib metadata.
+    ///
+    /// Alternative codegen backends may want to use different rlib or dylib formats than the
+    /// default native static archives and dynamic libraries.
+    fn metadata_loader(&self) -> Box<MetadataLoaderDyn> {
+        Box::new(crate::back::metadata::DefaultMetadataLoader)
+    }
+
+    fn provide(&self, _providers: &mut Providers) {}
+    fn provide_extern(&self, _providers: &mut Providers) {}
     fn codegen_crate<'tcx>(
         &self,
         tcx: TyCtxt<'tcx>,
diff --git a/compiler/rustc_driver/src/lib.rs b/compiler/rustc_driver/src/lib.rs
index c9b36dd0c24..b943977e4c2 100644
--- a/compiler/rustc_driver/src/lib.rs
+++ b/compiler/rustc_driver/src/lib.rs
@@ -21,7 +21,7 @@ use rustc_data_structures::sync::SeqCst;
 use rustc_errors::registry::{InvalidErrorCode, Registry};
 use rustc_errors::{ErrorReported, PResult};
 use rustc_feature::find_gated_cfg;
-use rustc_interface::util::{self, collect_crate_types, get_builtin_codegen_backend};
+use rustc_interface::util::{self, collect_crate_types, get_codegen_backend};
 use rustc_interface::{interface, Queries};
 use rustc_lint::LintStore;
 use rustc_metadata::locator;
@@ -499,7 +499,7 @@ fn make_input(
     }
 }
 
-// Whether to stop or continue compilation.
+/// Whether to stop or continue compilation.
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum Compilation {
     Stop,
@@ -765,9 +765,16 @@ pub fn version(binary: &str, matches: &getopts::Matches) {
         println!("commit-date: {}", unw(util::commit_date_str()));
         println!("host: {}", config::host_triple());
         println!("release: {}", unw(util::release_str()));
-        if cfg!(feature = "llvm") {
-            get_builtin_codegen_backend(&None, "llvm")().print_version();
-        }
+
+        let debug_flags = matches.opt_strs("Z");
+        let backend_name = debug_flags.iter().find_map(|x| {
+            if x.starts_with("codegen-backend=") {
+                Some(&x["codegen-backends=".len()..])
+            } else {
+                None
+            }
+        });
+        get_codegen_backend(&None, backend_name).print_version();
     }
 }
 
@@ -1039,8 +1046,8 @@ pub fn handle_options(args: &[String]) -> Option<getopts::Matches> {
     }
 
     // Don't handle -W help here, because we might first load plugins.
-    let r = matches.opt_strs("Z");
-    if r.iter().any(|x| *x == "help") {
+    let debug_flags = matches.opt_strs("Z");
+    if debug_flags.iter().any(|x| *x == "help") {
         describe_debug_flags();
         return None;
     }
@@ -1060,9 +1067,14 @@ pub fn handle_options(args: &[String]) -> Option<getopts::Matches> {
     }
 
     if cg_flags.iter().any(|x| *x == "passes=list") {
-        if cfg!(feature = "llvm") {
-            get_builtin_codegen_backend(&None, "llvm")().print_passes();
-        }
+        let backend_name = debug_flags.iter().find_map(|x| {
+            if x.starts_with("codegen-backend=") {
+                Some(&x["codegen-backends=".len()..])
+            } else {
+                None
+            }
+        });
+        get_codegen_backend(&None, backend_name).print_passes();
         return None;
     }
 
diff --git a/compiler/rustc_interface/src/queries.rs b/compiler/rustc_interface/src/queries.rs
index 969b526235b..2320f0b47d2 100644
--- a/compiler/rustc_interface/src/queries.rs
+++ b/compiler/rustc_interface/src/queries.rs
@@ -245,8 +245,7 @@ impl<'tcx> Queries<'tcx> {
         self.prepare_outputs.compute(|| {
             let expansion_result = self.expansion()?;
             let (krate, boxed_resolver, _) = &*expansion_result.peek();
-            let crate_name = self.crate_name()?;
-            let crate_name = crate_name.peek();
+            let crate_name = self.crate_name()?.peek();
             passes::prepare_outputs(
                 self.session(),
                 self.compiler,
@@ -343,32 +342,36 @@ impl<'tcx> Queries<'tcx> {
     }
 
     pub fn linker(&'tcx self) -> Result<Linker> {
-        let dep_graph = self.dep_graph()?;
-        let prepare_outputs = self.prepare_outputs()?;
-        let crate_hash = self.global_ctxt()?.peek_mut().enter(|tcx| tcx.crate_hash(LOCAL_CRATE));
-        let ongoing_codegen = self.ongoing_codegen()?;
-
         let sess = self.session().clone();
         let codegen_backend = self.codegen_backend().clone();
 
+        let dep_graph = self.dep_graph()?.peek().clone();
+        let prepare_outputs = self.prepare_outputs()?.take();
+        let crate_hash = self.global_ctxt()?.peek_mut().enter(|tcx| tcx.crate_hash(LOCAL_CRATE));
+        let ongoing_codegen = self.ongoing_codegen()?.take();
+
         Ok(Linker {
             sess,
-            dep_graph: dep_graph.peek().clone(),
-            prepare_outputs: prepare_outputs.take(),
-            crate_hash,
-            ongoing_codegen: ongoing_codegen.take(),
             codegen_backend,
+
+            dep_graph,
+            prepare_outputs,
+            crate_hash,
+            ongoing_codegen,
         })
     }
 }
 
 pub struct Linker {
+    // compilation inputs
     sess: Lrc<Session>,
+    codegen_backend: Lrc<Box<dyn CodegenBackend>>,
+
+    // compilation outputs
     dep_graph: DepGraph,
     prepare_outputs: OutputFilenames,
     crate_hash: Svh,
     ongoing_codegen: Box<dyn Any>,
-    codegen_backend: Lrc<Box<dyn CodegenBackend>>,
 }
 
 impl Linker {
diff --git a/compiler/rustc_interface/src/util.rs b/compiler/rustc_interface/src/util.rs
index 15cda299208..d1d0eee365d 100644
--- a/compiler/rustc_interface/src/util.rs
+++ b/compiler/rustc_interface/src/util.rs
@@ -32,7 +32,7 @@ use std::ops::DerefMut;
 use std::panic;
 use std::path::{Path, PathBuf};
 use std::sync::atomic::{AtomicBool, Ordering};
-use std::sync::{Arc, Mutex, Once};
+use std::sync::{Arc, Mutex};
 use std::thread;
 use tracing::info;
 
@@ -73,7 +73,10 @@ pub fn create_session(
     let codegen_backend = if let Some(make_codegen_backend) = make_codegen_backend {
         make_codegen_backend(&sopts)
     } else {
-        get_codegen_backend(&sopts)
+        get_codegen_backend(
+            &sopts.maybe_sysroot,
+            sopts.debugging_opts.codegen_backend.as_ref().map(|name| &name[..]),
+        )
     };
 
     // target_override is documented to be called before init(), so this is okay
@@ -241,35 +244,34 @@ fn load_backend_from_dylib(path: &Path) -> fn() -> Box<dyn CodegenBackend> {
     }
 }
 
-pub fn get_codegen_backend(sopts: &config::Options) -> Box<dyn CodegenBackend> {
-    static INIT: Once = Once::new();
-
-    static mut LOAD: fn() -> Box<dyn CodegenBackend> = || unreachable!();
+/// Get the codegen backend based on the name and specified sysroot.
+///
+/// A name of `None` indicates that the default backend should be used.
+pub fn get_codegen_backend(
+    maybe_sysroot: &Option<PathBuf>,
+    backend_name: Option<&str>,
+) -> Box<dyn CodegenBackend> {
+    static LOAD: SyncOnceCell<unsafe fn() -> Box<dyn CodegenBackend>> = SyncOnceCell::new();
 
-    INIT.call_once(|| {
+    let load = LOAD.get_or_init(|| {
         #[cfg(feature = "llvm")]
         const DEFAULT_CODEGEN_BACKEND: &str = "llvm";
 
         #[cfg(not(feature = "llvm"))]
         const DEFAULT_CODEGEN_BACKEND: &str = "cranelift";
 
-        let codegen_name = sopts
-            .debugging_opts
-            .codegen_backend
-            .as_ref()
-            .map(|name| &name[..])
-            .unwrap_or(DEFAULT_CODEGEN_BACKEND);
-
-        let backend = match codegen_name {
+        match backend_name.unwrap_or(DEFAULT_CODEGEN_BACKEND) {
             filename if filename.contains('.') => load_backend_from_dylib(filename.as_ref()),
-            codegen_name => get_builtin_codegen_backend(&sopts.maybe_sysroot, codegen_name),
-        };
-
-        unsafe {
-            LOAD = backend;
+            #[cfg(feature = "llvm")]
+            "llvm" => rustc_codegen_llvm::LlvmCodegenBackend::new,
+            backend_name => get_codegen_sysroot(maybe_sysroot, backend_name),
         }
     });
-    unsafe { LOAD() }
+
+    // SAFETY: In case of a builtin codegen backend this is safe. In case of an external codegen
+    // backend we hope that the backend links against the same rustc_driver version. If this is not
+    // the case, we get UB.
+    unsafe { load() }
 }
 
 // This is used for rustdoc, but it uses similar machinery to codegen backend
@@ -387,17 +389,6 @@ fn sysroot_candidates() -> Vec<PathBuf> {
     }
 }
 
-pub fn get_builtin_codegen_backend(
-    maybe_sysroot: &Option<PathBuf>,
-    backend_name: &str,
-) -> fn() -> Box<dyn CodegenBackend> {
-    match backend_name {
-        #[cfg(feature = "llvm")]
-        "llvm" => rustc_codegen_llvm::LlvmCodegenBackend::new,
-        _ => get_codegen_sysroot(maybe_sysroot, backend_name),
-    }
-}
-
 pub fn get_codegen_sysroot(
     maybe_sysroot: &Option<PathBuf>,
     backend_name: &str,
diff --git a/src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs b/src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs
index a9e99d3c10e..443e2df357f 100644
--- a/src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs
+++ b/src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs
@@ -1,4 +1,5 @@
 #![feature(rustc_private)]
+#![deny(warnings)]
 
 extern crate rustc_codegen_ssa;
 extern crate rustc_errors;
@@ -15,44 +16,28 @@ use rustc_codegen_ssa::back::linker::LinkerInfo;
 use rustc_codegen_ssa::traits::CodegenBackend;
 use rustc_codegen_ssa::{CodegenResults, CrateInfo};
 use rustc_data_structures::fx::FxHashMap;
-use rustc_data_structures::sync::MetadataRef;
 use rustc_errors::ErrorReported;
-use rustc_middle::dep_graph::DepGraph;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
-use rustc_middle::middle::cstore::{EncodedMetadata, MetadataLoader, MetadataLoaderDyn};
-use rustc_middle::ty::query::Providers;
+use rustc_middle::middle::cstore::EncodedMetadata;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::OutputFilenames;
 use rustc_session::Session;
-use rustc_target::spec::Target;
 use std::any::Any;
-use std::path::Path;
 
 struct TheBackend;
 
 impl CodegenBackend for TheBackend {
-    fn metadata_loader(&self) -> Box<MetadataLoaderDyn> {
-        Box::new(rustc_codegen_ssa::back::metadata::DefaultMetadataLoader)
-    }
-
-    fn provide(&self, providers: &mut Providers) {}
-    fn provide_extern(&self, providers: &mut Providers) {}
-
     fn codegen_crate<'a, 'tcx>(
         &self,
         tcx: TyCtxt<'tcx>,
         metadata: EncodedMetadata,
         _need_metadata_module: bool,
     ) -> Box<dyn Any> {
-        use rustc_hir::def_id::LOCAL_CRATE;
-
         Box::new(CodegenResults {
-            crate_name: tcx.crate_name(LOCAL_CRATE),
             modules: vec![],
             allocator_module: None,
             metadata_module: None,
             metadata,
-            windows_subsystem: None,
             linker_info: LinkerInfo::new(tcx, "fake_target_cpu".to_string()),
             crate_info: CrateInfo::new(tcx),
         })
@@ -77,7 +62,7 @@ impl CodegenBackend for TheBackend {
     ) -> Result<(), ErrorReported> {
         use rustc_session::{config::CrateType, output::out_filename};
         use std::io::Write;
-        let crate_name = codegen_results.crate_name;
+        let crate_name = codegen_results.crate_info.local_crate_name;
         for &crate_type in sess.opts.crate_types.iter() {
             if crate_type != CrateType::Rlib {
                 sess.fatal(&format!("Crate type is {:?}", crate_type));