Auto merge of #76975 - RalfJung:rollup-s2wiuqr, r=RalfJung

Rollup of 15 pull requests

Successful merges:

 - #76732 (Add docs for `BasicBlock`)
 - #76832 (Let backends define custom targets)
 - #76866 (Remove unused feature gates from library/ crates)
 - #76875 (Move to intra-doc links in library/alloc/src/collections/binary_heap.rs)
 - #76876 (Move to intra-doc links in collections/btree/map.rs and collections/linked_list.rs)
 - #76877 (Move to intra-doc links in collections/vec_deque.rs and collections/vec_deque/drain.rs)
 - #76878 (Move the version number to a plaintext file)
 - #76883 (README.md: Remove prompts from code blocks)
 - #76887 (Add missing examples on HashSet iter types)
 - #76890 (use matches!() macro for simple if let conditions)
 - #76891 (don't take `TyCtxt` by reference)
 - #76910 (transmute: use diagnostic item)
 - #76924 (Add tracking issue for feature(unix_socket_peek))
 - #76926 (BTreeMap: code readability tweaks)
 - #76940 (Don't allow implementing trait directly on type-alias-impl-trait)

Failed merges:

r? `@ghost`

1 files changed, 7 insertions, 0 deletions

diff --git a/compiler/rustc_codegen_ssa/src/traits/backend.rs b/compiler/rustc_codegen_ssa/src/traits/backend.rs
index 3522ea01153..90520f77e3c 100644
--- a/compiler/rustc_codegen_ssa/src/traits/backend.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/backend.rs
@@ -15,6 +15,7 @@ use rustc_session::{
 };
 use rustc_span::symbol::Symbol;
 use rustc_target::abi::LayoutOf;
+use rustc_target::spec::Target;
 
 pub use rustc_data_structures::sync::MetadataRef;
 
@@ -54,6 +55,12 @@ pub trait CodegenBackend {
     fn print_passes(&self) {}
     fn print_version(&self) {}
 
+    /// If this plugin provides additional builtin targets, provide the one enabled by the options here.
+    /// Be careful: this is called *before* init() is called.
+    fn target_override(&self, _opts: &config::Options) -> Option<Target> {
+        None
+    }
+
     fn metadata_loader(&self) -> Box<MetadataLoaderDyn>;
     fn provide(&self, _providers: &mut Providers);
     fn provide_extern(&self, _providers: &mut Providers);