Revert "Auto merge of #127537 - veluca93:struct_tf, r=BoxyUwU"

This reverts commit acb4e8b6251f1d8da36f08e7a70fa23fc581839e, reversing
changes made to 100fde5246bf56f22fb5cc85374dd841296fce0e.

1 files changed, 10 insertions, 115 deletions

diff --git a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
index 209750d6ba6..4ab20c154cc 100644
--- a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
+++ b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
@@ -1,6 +1,5 @@
 use rustc_ast::{ast, attr, MetaItemKind, NestedMetaItem};
 use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr};
-use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::codes::*;
 use rustc_errors::{struct_span_code_err, DiagMessage, SubdiagMessage};
 use rustc_hir as hir;
@@ -9,7 +8,7 @@ use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE};
 use rustc_hir::weak_lang_items::WEAK_LANG_ITEMS;
 use rustc_hir::{lang_items, LangItem};
 use rustc_middle::middle::codegen_fn_attrs::{
-    CodegenFnAttrFlags, CodegenFnAttrs, PatchableFunctionEntry, TargetFeature,
+    CodegenFnAttrFlags, CodegenFnAttrs, PatchableFunctionEntry,
 };
 use rustc_middle::mir::mono::Linkage;
 use rustc_middle::query::Providers;
@@ -18,7 +17,6 @@ use rustc_session::lint;
 use rustc_session::parse::feature_err;
 use rustc_span::symbol::Ident;
 use rustc_span::{sym, Span};
-use rustc_target::abi::VariantIdx;
 use rustc_target::spec::{abi, SanitizerSet};
 
 use crate::errors;
@@ -80,13 +78,6 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
     let mut link_ordinal_span = None;
     let mut no_sanitize_span = None;
 
-    let fn_sig_outer = || {
-        use DefKind::*;
-
-        let def_kind = tcx.def_kind(did);
-        if let Fn | AssocFn | Variant | Ctor(..) = def_kind { Some(tcx.fn_sig(did)) } else { None }
-    };
-
     for attr in attrs.iter() {
         // In some cases, attribute are only valid on functions, but it's the `check_attr`
         // pass that check that they aren't used anywhere else, rather this module.
@@ -94,12 +85,16 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
         // functions (such as calling `fn_sig`, which ICEs if given a non-function). We also
         // report a delayed bug, just in case `check_attr` isn't doing its job.
         let fn_sig = || {
-            let sig = fn_sig_outer();
-            if sig.is_none() {
+            use DefKind::*;
+
+            let def_kind = tcx.def_kind(did);
+            if let Fn | AssocFn | Variant | Ctor(..) = def_kind {
+                Some(tcx.fn_sig(did))
+            } else {
                 tcx.dcx()
                     .span_delayed_bug(attr.span, "this attribute can only be applied to functions");
+                None
             }
-            sig
         };
 
         let Some(Ident { name, .. }) = attr.ident() else {
@@ -618,93 +613,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
         }
     }
 
-    if let Some(sig) = fn_sig_outer() {
-        // Collect target features from types reachable from arguments.
-        // We define a type as "reachable" if:
-        //  - it is a function argument
-        //  - it is a field of a reachable struct
-        //  - there is a reachable reference to it
-        // FIXME(struct_target_features): we may want to cache the result of this computation.
-        let mut visited_types = FxHashSet::default();
-        let mut reachable_types: Vec<_> = sig.skip_binder().inputs().skip_binder().to_owned();
-        let mut additional_tf = vec![];
-
-        while let Some(ty) = reachable_types.pop() {
-            if visited_types.contains(&ty) {
-                continue;
-            }
-            visited_types.insert(ty);
-            match ty.kind() {
-                ty::Alias(..) => {
-                    if let Ok(t) =
-                        tcx.try_normalize_erasing_regions(tcx.param_env(did.to_def_id()), ty)
-                    {
-                        reachable_types.push(t)
-                    }
-                }
-
-                ty::Ref(_, inner, _) => reachable_types.push(*inner),
-                ty::Tuple(tys) => reachable_types.extend(tys.iter()),
-                ty::Adt(adt_def, args) => {
-                    additional_tf.extend_from_slice(tcx.struct_target_features(adt_def.did()));
-                    // This only recurses into structs as i.e. an Option<TargetFeature> is an ADT
-                    // that doesn't actually always contain a TargetFeature.
-                    if adt_def.is_struct() {
-                        reachable_types.extend(
-                            adt_def
-                                .variant(VariantIdx::from_usize(0))
-                                .fields
-                                .iter()
-                                .map(|field| field.ty(tcx, args)),
-                        );
-                    }
-                }
-                ty::Bool
-                | ty::Char
-                | ty::Int(..)
-                | ty::Uint(..)
-                | ty::Float(..)
-                | ty::Foreign(..)
-                | ty::Str
-                | ty::Array(..)
-                | ty::Pat(..)
-                | ty::Slice(..)
-                | ty::RawPtr(..)
-                | ty::FnDef(..)
-                | ty::FnPtr(..)
-                | ty::Dynamic(..)
-                | ty::Closure(..)
-                | ty::CoroutineClosure(..)
-                | ty::Coroutine(..)
-                | ty::CoroutineWitness(..)
-                | ty::Never
-                | ty::Param(..)
-                | ty::Bound(..)
-                | ty::Placeholder(..)
-                | ty::Infer(..)
-                | ty::Error(..) => (),
-            }
-        }
-
-        // FIXME(struct_target_features): is this really necessary?
-        if !additional_tf.is_empty() && sig.skip_binder().abi() != abi::Abi::Rust {
-            tcx.dcx().span_err(
-                tcx.hir().span(tcx.local_def_id_to_hir_id(did)),
-                "cannot use a struct with target features in a function with non-Rust ABI",
-            );
-        }
-        if !additional_tf.is_empty() && codegen_fn_attrs.inline == InlineAttr::Always {
-            tcx.dcx().span_err(
-                tcx.hir().span(tcx.local_def_id_to_hir_id(did)),
-                "cannot use a struct with target features in a #[inline(always)] function",
-            );
-        }
-        codegen_fn_attrs
-            .target_features
-            .extend(additional_tf.iter().map(|tf| TargetFeature { implied: true, ..*tf }));
-    }
-
-    // If a function uses non-default target_features it can't be inlined into general
+    // If a function uses #[target_feature] it can't be inlined into general
     // purpose functions as they wouldn't have the right target features
     // enabled. For that reason we also forbid #[inline(always)] as it can't be
     // respected.
@@ -849,20 +758,6 @@ fn check_link_name_xor_ordinal(
     }
 }
 
-fn struct_target_features(tcx: TyCtxt<'_>, def_id: LocalDefId) -> &[TargetFeature] {
-    let mut features = vec![];
-    let supported_features = tcx.supported_target_features(LOCAL_CRATE);
-    for attr in tcx.get_attrs(def_id, sym::target_feature) {
-        from_target_feature(tcx, attr, supported_features, &mut features);
-    }
-    tcx.arena.alloc_slice(&features)
-}
-
 pub fn provide(providers: &mut Providers) {
-    *providers = Providers {
-        codegen_fn_attrs,
-        should_inherit_track_caller,
-        struct_target_features,
-        ..*providers
-    };
+    *providers = Providers { codegen_fn_attrs, should_inherit_track_caller, ..*providers };
 }