CFI: Fix (3) of core and std have explict CFI violations

Fixes (3) of #115199 by transforming function items, closures, and Fn
trait objects into function pointers.

compiler/rustc_middle/src/ty/sty.rs

@@ -744,6 +744,52 @@ impl<'tcx> PolyExistentialPredicate<'tcx> {
 }
 
 impl<'tcx> List<ty::PolyExistentialPredicate<'tcx>> {
+    /// Returns the list of arguments if principal is an Fn trait.
+    pub fn fn_trait_args(&self, tcx: TyCtxt<'tcx>) -> Option<&List<Ty<'tcx>>> {
+        if self.is_fn_trait(tcx) {
+            if let Some(args) = self.principal_args() && !args.is_empty() && args[0].expect_ty().is_tuple() {
+                Some(args[0].expect_ty().tuple_fields())
+            } else {
+                Some(List::empty())
+            }
+        } else {
+            None
+        }
+    }
+
+    /// Returns the output if principal is an Fn trait.
+    pub fn fn_trait_output(&self, tcx: TyCtxt<'tcx>) -> Option<Ty<'tcx>> {
+        if self.is_fn_trait(tcx) {
+            if let Some(projection) = self.projection_bounds().next() && let Some(ty) = projection.skip_binder().term.ty() {
+                Some(ty)
+            } else {
+                Some(Ty::new_unit(tcx))
+            }
+        } else {
+            None
+        }
+    }
+
+    /// Returns the signature if principal is an Fn trait.
+    pub fn fn_trait_sig(&self, tcx: TyCtxt<'tcx>) -> Option<FnSig<'tcx>> {
+        if self.is_fn_trait(tcx) {
+            Some(tcx.mk_fn_sig(
+                self.fn_trait_args(tcx).unwrap(),
+                self.fn_trait_output(tcx).unwrap(),
+                false,
+                hir::Unsafety::Normal,
+                Abi::Rust,
+            ))
+        } else {
+            None
+        }
+    }
+
+    /// Returns true if principal is an Fn trait.
+    pub fn is_fn_trait(&self, tcx: TyCtxt<'tcx>) -> bool {
+        if let Some(principal) = self.principal() && tcx.is_fn_trait(principal.skip_binder().def_id) { true } else { false }
+    }
+
     /// Returns the "principal `DefId`" of this set of existential predicates.
     ///
     /// A Rust trait object type consists (in addition to a lifetime bound)
@@ -778,6 +824,12 @@ impl<'tcx> List<ty::PolyExistentialPredicate<'tcx>> {
             .transpose()
     }
 
+    /// Returns the principal list of arguments.
+    pub fn principal_args(&self) -> Option<&List<GenericArg<'tcx>>> {
+        self.principal().map(|trait_ref| trait_ref.skip_binder().args)
+    }
+
+    /// Returns the principal DefId.
     pub fn principal_def_id(&self) -> Option<DefId> {
         self.principal().map(|trait_ref| trait_ref.skip_binder().def_id)
     }
@@ -2246,6 +2298,11 @@ impl<'tcx> Ty<'tcx> {
         self.0.0.flags
     }
 
+    #[inline]
+    pub fn is_tuple(self) -> bool {
+        matches!(self.kind(), Tuple(..))
+    }
+
     #[inline]
     pub fn is_unit(self) -> bool {
         match self.kind() {
@@ -2599,6 +2656,11 @@ impl<'tcx> Ty<'tcx> {
         matches!(self.kind(), FnDef(..) | FnPtr(_))
     }
 
+    #[inline]
+    pub fn is_fn_def(self) -> bool {
+        matches!(self.kind(), FnDef(..))
+    }
+
     #[inline]
     pub fn is_fn_ptr(self) -> bool {
         matches!(self.kind(), FnPtr(_))

compiler/rustc_symbol_mangling/src/lib.rs

@@ -88,6 +88,8 @@
 //! DefPaths which are much more robust in the face of changes to the code base.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
+#![feature(iter_order_by)]
+#![feature(let_chains)]
 #![feature(never_type)]
 #![recursion_limit = "256"]
 #![allow(rustc::potential_query_instability)]

compiler/rustc_symbol_mangling/src/typeid.rs

@@ -4,7 +4,7 @@
 /// For more information about LLVM CFI and cross-language LLVM CFI support for the Rust compiler,
 /// see design document in the tracking issue #89653.
 use bitflags::bitflags;
-use rustc_middle::ty::{FnSig, Instance, Ty, TyCtxt};
+use rustc_middle::ty::{Instance, List, Ty, TyCtxt};
 use rustc_target::abi::call::FnAbi;
 use std::hash::Hasher;
 use twox_hash::XxHash64;
@@ -26,16 +26,11 @@ pub fn typeid_for_fnabi<'tcx>(
     fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
     options: TypeIdOptions,
 ) -> String {
-    typeid_itanium_cxx_abi::typeid_for_fnabi(tcx, fn_abi, options)
-}
-
-/// Returns a type metadata identifier for the specified FnSig.
-pub fn typeid_for_fnsig<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    fn_sig: &FnSig<'tcx>,
-    options: TypeIdOptions,
-) -> String {
-    typeid_itanium_cxx_abi::typeid_for_fnsig(tcx, fn_sig, options)
+    typeid_itanium_cxx_abi::typeid_for_fnabi(
+        tcx,
+        &typeid_itanium_cxx_abi::transform_fnabi(tcx, &fn_abi, options, None),
+        options,
+    )
 }
 
 /// Returns a type metadata identifier for the specified Instance.
@@ -44,7 +39,16 @@ pub fn typeid_for_instance<'tcx>(
     instance: &Instance<'tcx>,
     options: TypeIdOptions,
 ) -> String {
-    typeid_itanium_cxx_abi::typeid_for_instance(tcx, instance, options)
+    let fn_abi = tcx
+        .fn_abi_of_instance(tcx.param_env(instance.def_id()).and((*instance, List::empty())))
+        .unwrap_or_else(|instance| {
+            bug!("typeid_for_instance: couldn't get fn_abi of instance {:?}", instance)
+        });
+    typeid_itanium_cxx_abi::typeid_for_fnabi(
+        tcx,
+        &typeid_itanium_cxx_abi::transform_fnabi(tcx, &fn_abi, options, Some(instance)),
+        options,
+    )
 }
 
 /// Returns a KCFI type metadata identifier for the specified FnAbi.
@@ -56,20 +60,14 @@ pub fn kcfi_typeid_for_fnabi<'tcx>(
     // A KCFI type metadata identifier is a 32-bit constant produced by taking the lower half of the
     // xxHash64 of the type metadata identifier. (See llvm/llvm-project@cff5bef.)
     let mut hash: XxHash64 = Default::default();
-    hash.write(typeid_itanium_cxx_abi::typeid_for_fnabi(tcx, fn_abi, options).as_bytes());
-    hash.finish() as u32
-}
-
-/// Returns a KCFI type metadata identifier for the specified FnSig.
-pub fn kcfi_typeid_for_fnsig<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    fn_sig: &FnSig<'tcx>,
-    options: TypeIdOptions,
-) -> u32 {
-    // A KCFI type metadata identifier is a 32-bit constant produced by taking the lower half of the
-    // xxHash64 of the type metadata identifier. (See llvm/llvm-project@cff5bef.)
-    let mut hash: XxHash64 = Default::default();
-    hash.write(typeid_itanium_cxx_abi::typeid_for_fnsig(tcx, fn_sig, options).as_bytes());
+    hash.write(
+        typeid_itanium_cxx_abi::typeid_for_fnabi(
+            tcx,
+            &typeid_itanium_cxx_abi::transform_fnabi(tcx, &fn_abi, options, None),
+            options,
+        )
+        .as_bytes(),
+    );
     hash.finish() as u32
 }
 
@@ -79,9 +77,21 @@ pub fn kcfi_typeid_for_instance<'tcx>(
     instance: &Instance<'tcx>,
     options: TypeIdOptions,
 ) -> u32 {
+    let fn_abi = tcx
+        .fn_abi_of_instance(tcx.param_env(instance.def_id()).and((*instance, List::empty())))
+        .unwrap_or_else(|instance| {
+            bug!("typeid_for_instance: couldn't get fn_abi of instance {:?}", instance)
+        });
     // A KCFI type metadata identifier is a 32-bit constant produced by taking the lower half of the
     // xxHash64 of the type metadata identifier. (See llvm/llvm-project@cff5bef.)
     let mut hash: XxHash64 = Default::default();
-    hash.write(typeid_itanium_cxx_abi::typeid_for_instance(tcx, instance, options).as_bytes());
+    hash.write(
+        typeid_itanium_cxx_abi::typeid_for_fnabi(
+            tcx,
+            &typeid_itanium_cxx_abi::transform_fnabi(tcx, &fn_abi, options, Some(instance)),
+            options,
+        )
+        .as_bytes(),
+    );
     hash.finish() as u32
 }