Revert PR #93718 (use of #[used(linker)]) due to breakage on multiple platforms.

compiler/rustc_codegen_llvm/src/consts.rs

@@ -537,20 +537,10 @@ impl<'ll> StaticMethods for CodegenCx<'ll, '_> {
 
  // The semantics of #[used] in Rust only require the symbol to make it into the
  // object file. It is explicitly allowed for the linker to strip the symbol if it
- // is dead, which means we are allowed use `llvm.compiler.used` instead of
- // `llvm.used` here.
- //
+ // is dead. As such, use llvm.compiler.used instead of llvm.used.
  // Additionally, https://reviews.llvm.org/D97448 in LLVM 13 started emitting unique
  // sections with SHF_GNU_RETAIN flag for llvm.used symbols, which may trigger bugs
- // in the handling of `.init_array` (the static constructor list) in versions of
- // the gold linker (prior to the one released with binutils 2.36).
- //
- // That said, we only ever emit these when compiling for ELF targets, unless
- // `#[used(compiler)]` is explicitly requested. This is to avoid similar breakage
- // on other targets, in particular MachO targets have *their* static constructor
- // lists broken if `llvm.compiler.used` is emitted rather than llvm.used. However,
- // that check happens when assigning the `CodegenFnAttrFlags` in `rustc_typeck`,
- // so we don't need to take care of it here.
+ // in some versions of the gold linker.
  self.add_compiler_used_global(g);
  }
  if attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER) {

compiler/rustc_codegen_ssa/src/traits/statics.rs

@@ -13,9 +13,7 @@ pub trait StaticMethods: BackendTypes {
  /// Same as add_used_global(), but only prevent the compiler from potentially removing an
  /// otherwise unused symbol. The linker is still permitted to drop it.
  ///
- /// This corresponds to the documented semantics of the `#[used]` attribute, although
- /// on some targets (non-ELF), we may use `add_used_global` for `#[used]` statics
- /// instead.
+ /// This corresponds to the semantics of the `#[used]` attribute.
  fn add_compiler_used_global(&self, global: Self::Value);
 }
 

compiler/rustc_typeck/src/collect.rs

@@ -2818,37 +2818,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: DefId) -> CodegenFnAttrs {
  )
  .emit();
  }
- None => {
- // Unfortunately, unconditionally using `llvm.used` causes
- // issues in handling `.init_array` with the gold linker,
- // but using `llvm.compiler.used` caused a nontrival amount
- // of unintentional ecosystem breakage -- particularly on
- // Mach-O targets.
- //
- // As a result, we emit `llvm.compiler.used` only on ELF
- // targets. This is somewhat ad-hoc, but actually follows
- // our pre-LLVM 13 behavior (prior to the ecosystem
- // breakage), and seems to match `clang`'s behavior as well
- // (both before and after LLVM 13), possibly because they
- // have similar compatibility concerns to us. See
- // https:/rust-lang/rust/issues/47384#issuecomment-1019080146
- // and following comments for some discussion of this, as
- // well as the comments in `rustc_codegen_llvm` where these
- // flags are handled.
- //
- // Anyway, to be clear: this is still up in the air
- // somewhat, and is subject to change in the future (which
- // is a good thing, because this would ideally be a bit
- // more firmed up).
- let is_like_elf = !(tcx.sess.target.is_like_osx
- || tcx.sess.target.is_like_windows
- || tcx.sess.target.is_like_wasm);
- codegen_fn_attrs.flags = if is_like_elf {
- CodegenFnAttrFlags::USED
- } else {
- CodegenFnAttrFlags::USED_LINKER
- };
- }
+ None => codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED,
  }
  } else if attr.has_name(sym::cmse_nonsecure_entry) {
  if !matches!(tcx.fn_sig(did).abi(), abi::Abi::C { .. }) {