Auto merge of #135592 - matthiaskrgr:rollup-4t69l7i, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #134754 (Implement `use` associated items of traits)
 - #135481 (coverage: Completely overhaul counter assignment, using node-flow graphs)
 - #135504 (Allow coercing safe-to-call target_feature functions to safe fn pointers)
 - #135561 (Update docs for `-Clink-dead-code` to discourage its use)
 - #135574 (ci: mirror ubuntu:22.04 to ghcr.io)
 - #135585 (resolve symlinks of LLVM tool binaries before copying them)
 - #135588 (Add license-metadata.json to rustc-src tarball.)

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 32 insertions, 1 deletions

diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index fab0047babf..7035e641f39 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -60,7 +60,7 @@ use crate::dep_graph::{DepGraph, DepKindStruct};
 use crate::infer::canonical::{CanonicalParamEnvCache, CanonicalVarInfo, CanonicalVarInfos};
 use crate::lint::lint_level;
 use crate::metadata::ModChild;
-use crate::middle::codegen_fn_attrs::CodegenFnAttrs;
+use crate::middle::codegen_fn_attrs::{CodegenFnAttrs, TargetFeature};
 use crate::middle::{resolve_bound_vars, stability};
 use crate::mir::interpret::{self, Allocation, ConstAllocation};
 use crate::mir::{Body, Local, Place, PlaceElem, ProjectionKind, Promoted};
@@ -1776,6 +1776,37 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn dcx(self) -> DiagCtxtHandle<'tcx> {
         self.sess.dcx()
     }
+
+    pub fn is_target_feature_call_safe(
+        self,
+        callee_features: &[TargetFeature],
+        body_features: &[TargetFeature],
+    ) -> bool {
+        // If the called function has target features the calling function hasn't,
+        // the call requires `unsafe`. Don't check this on wasm
+        // targets, though. For more information on wasm see the
+        // is_like_wasm check in hir_analysis/src/collect.rs
+        self.sess.target.options.is_like_wasm
+            || callee_features
+                .iter()
+                .all(|feature| body_features.iter().any(|f| f.name == feature.name))
+    }
+
+    /// Returns the safe version of the signature of the given function, if calling it
+    /// would be safe in the context of the given caller.
+    pub fn adjust_target_feature_sig(
+        self,
+        fun_def: DefId,
+        fun_sig: ty::Binder<'tcx, ty::FnSig<'tcx>>,
+        caller: DefId,
+    ) -> Option<ty::Binder<'tcx, ty::FnSig<'tcx>>> {
+        let fun_features = &self.codegen_fn_attrs(fun_def).target_features;
+        let callee_features = &self.codegen_fn_attrs(caller).target_features;
+        if self.is_target_feature_call_safe(&fun_features, &callee_features) {
+            return Some(fun_sig.map_bound(|sig| ty::FnSig { safety: hir::Safety::Safe, ..sig }));
+        }
+        None
+    }
 }
 
 impl<'tcx> TyCtxtAt<'tcx> {