Auto merge of #129691 - matthiaskrgr:rollup-owlcr3m, r=matthiaskrgr

Rollup of 11 pull requests

Successful merges:

 - #129421 (add repr to the allowlist for naked functions)
 - #129480 (docs: correct panic conditions for rem_euclid and similar functions)
 - #129551 (ub_checks intrinsics: fall back to cfg(ub_checks))
 - #129608 (const-eval: do not make UbChecks behavior depend on current crate's flags)
 - #129613 (interpret: do not make const-eval query result depend on tcx.sess)
 - #129641 (rustdoc: fix missing resource suffix on `crates.js`)
 - #129657 (Rename `BikeshedIntrinsicFrom` to `TransmuteFrom`)
 - #129666 (interpret: add missing alignment check in raw_eq)
 - #129667 (Rustc driver cleanup)
 - #129668 (Fix Pin::set bounds regression)
 - #129686 (coverage: Rename `CodeRegion` to `SourceRegion`)

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

4 files changed, 40 insertions, 48 deletions

diff --git a/compiler/rustc_const_eval/src/interpret/call.rs b/compiler/rustc_const_eval/src/interpret/call.rs
index f99283c49f5..61e8007e10e 100644
--- a/compiler/rustc_const_eval/src/interpret/call.rs
+++ b/compiler/rustc_const_eval/src/interpret/call.rs
@@ -311,34 +311,6 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         Ok(())
     }
 
-    fn check_fn_target_features(&self, instance: ty::Instance<'tcx>) -> InterpResult<'tcx, ()> {
-        // Calling functions with `#[target_feature]` is not unsafe on WASM, see #84988
-        let attrs = self.tcx.codegen_fn_attrs(instance.def_id());
-        if !self.tcx.sess.target.is_like_wasm
-            && attrs
-                .target_features
-                .iter()
-                .any(|feature| !self.tcx.sess.target_features.contains(&feature.name))
-        {
-            throw_ub_custom!(
-                fluent::const_eval_unavailable_target_features_for_fn,
-                unavailable_feats = attrs
-                    .target_features
-                    .iter()
-                    .filter(|&feature| !feature.implied
-                        && !self.tcx.sess.target_features.contains(&feature.name))
-                    .fold(String::new(), |mut s, feature| {
-                        if !s.is_empty() {
-                            s.push_str(", ");
-                        }
-                        s.push_str(feature.name.as_str());
-                        s
-                    }),
-            );
-        }
-        Ok(())
-    }
-
     /// The main entry point for creating a new stack frame: performs ABI checks and initializes
     /// arguments.
     #[instrument(skip(self), level = "trace")]
@@ -360,20 +332,18 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             throw_unsup_format!("calling a c-variadic function is not supported");
         }
 
-        if M::enforce_abi(self) {
-            if caller_fn_abi.conv != callee_fn_abi.conv {
-                throw_ub_custom!(
-                    fluent::const_eval_incompatible_calling_conventions,
-                    callee_conv = format!("{:?}", callee_fn_abi.conv),
-                    caller_conv = format!("{:?}", caller_fn_abi.conv),
-                )
-            }
+        if caller_fn_abi.conv != callee_fn_abi.conv {
+            throw_ub_custom!(
+                fluent::const_eval_incompatible_calling_conventions,
+                callee_conv = format!("{:?}", callee_fn_abi.conv),
+                caller_conv = format!("{:?}", caller_fn_abi.conv),
+            )
         }
 
         // Check that all target features required by the callee (i.e., from
         // the attribute `#[target_feature(enable = ...)]`) are enabled at
         // compile time.
-        self.check_fn_target_features(instance)?;
+        M::check_fn_target_features(self, instance)?;
 
         if !callee_fn_abi.can_unwind {
             // The callee cannot unwind, so force the `Unreachable` unwind handling.
diff --git a/compiler/rustc_const_eval/src/interpret/intrinsics.rs b/compiler/rustc_const_eval/src/interpret/intrinsics.rs
index aef39b9af2f..bedc56de0da 100644
--- a/compiler/rustc_const_eval/src/interpret/intrinsics.rs
+++ b/compiler/rustc_const_eval/src/interpret/intrinsics.rs
@@ -684,19 +684,19 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         assert!(layout.is_sized());
 
         let get_bytes = |this: &InterpCx<'tcx, M>,
-                         op: &OpTy<'tcx, <M as Machine<'tcx>>::Provenance>,
-                         size|
+                         op: &OpTy<'tcx, <M as Machine<'tcx>>::Provenance>|
          -> InterpResult<'tcx, &[u8]> {
             let ptr = this.read_pointer(op)?;
-            let Some(alloc_ref) = self.get_ptr_alloc(ptr, size)? else {
+            this.check_ptr_align(ptr, layout.align.abi)?;
+            let Some(alloc_ref) = self.get_ptr_alloc(ptr, layout.size)? else {
                 // zero-sized access
                 return Ok(&[]);
             };
             alloc_ref.get_bytes_strip_provenance()
         };
 
-        let lhs_bytes = get_bytes(self, lhs, layout.size)?;
-        let rhs_bytes = get_bytes(self, rhs, layout.size)?;
+        let lhs_bytes = get_bytes(self, lhs)?;
+        let rhs_bytes = get_bytes(self, rhs)?;
         Ok(Scalar::from_bool(lhs_bytes == rhs_bytes))
     }
 }
diff --git a/compiler/rustc_const_eval/src/interpret/machine.rs b/compiler/rustc_const_eval/src/interpret/machine.rs
index 761ab81e228..88453245b84 100644
--- a/compiler/rustc_const_eval/src/interpret/machine.rs
+++ b/compiler/rustc_const_eval/src/interpret/machine.rs
@@ -173,11 +173,6 @@ pub trait Machine<'tcx>: Sized {
         false
     }
 
-    /// Whether function calls should be [ABI](CallAbi)-checked.
-    fn enforce_abi(_ecx: &InterpCx<'tcx, Self>) -> bool {
-        true
-    }
-
     /// Whether Assert(OverflowNeg) and Assert(Overflow) MIR terminators should actually
     /// check for overflow.
     fn ignore_optional_overflow_checks(_ecx: &InterpCx<'tcx, Self>) -> bool;
@@ -238,6 +233,13 @@ pub trait Machine<'tcx>: Sized {
         unwind: mir::UnwindAction,
     ) -> InterpResult<'tcx, Option<ty::Instance<'tcx>>>;
 
+    /// Check whether the given function may be executed on the current machine, in terms of the
+    /// target features is requires.
+    fn check_fn_target_features(
+        _ecx: &InterpCx<'tcx, Self>,
+        _instance: ty::Instance<'tcx>,
+    ) -> InterpResult<'tcx>;
+
     /// Called to evaluate `Assert` MIR terminators that trigger a panic.
     fn assert_panic(
         ecx: &mut InterpCx<'tcx, Self>,
@@ -280,6 +282,9 @@ pub trait Machine<'tcx>: Sized {
         Ok(())
     }
 
+    /// Determines the result of a `NullaryOp::UbChecks` invocation.
+    fn ub_checks(_ecx: &InterpCx<'tcx, Self>) -> InterpResult<'tcx, bool>;
+
     /// Called when the interpreter encounters a `StatementKind::ConstEvalCounter` instruction.
     /// You can use this to detect long or endlessly running programs.
     #[inline]
@@ -615,6 +620,16 @@ pub macro compile_time_machine(<$tcx: lifetime>) {
     }
 
     #[inline(always)]
+    fn check_fn_target_features(
+        _ecx: &InterpCx<$tcx, Self>,
+        _instance: ty::Instance<$tcx>,
+    ) -> InterpResult<$tcx> {
+        // For now we don't do any checking here. We can't use `tcx.sess` because that can differ
+        // between crates, and we need to ensure that const-eval always behaves the same.
+        Ok(())
+    }
+
+    #[inline(always)]
     fn call_extra_fn(
         _ecx: &mut InterpCx<$tcx, Self>,
         fn_val: !,
@@ -628,6 +643,13 @@ pub macro compile_time_machine(<$tcx: lifetime>) {
     }
 
     #[inline(always)]
+    fn ub_checks(_ecx: &InterpCx<$tcx, Self>) -> InterpResult<$tcx, bool> {
+        // We can't look at `tcx.sess` here as that can differ across crates, which can lead to
+        // unsound differences in evaluating the same constant at different instantiation sites.
+        Ok(true)
+    }
+
+    #[inline(always)]
     fn adjust_global_allocation<'b>(
         _ecx: &InterpCx<$tcx, Self>,
         _id: AllocId,
diff --git a/compiler/rustc_const_eval/src/interpret/operator.rs b/compiler/rustc_const_eval/src/interpret/operator.rs
index 2f860f9f942..e9ba12dbcc4 100644
--- a/compiler/rustc_const_eval/src/interpret/operator.rs
+++ b/compiler/rustc_const_eval/src/interpret/operator.rs
@@ -512,7 +512,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                     self.tcx.offset_of_subfield(self.param_env, layout, fields.iter()).bytes();
                 ImmTy::from_uint(val, usize_layout())
             }
-            UbChecks => ImmTy::from_bool(self.tcx.sess.ub_checks(), *self.tcx),
+            UbChecks => ImmTy::from_bool(M::ub_checks(self)?, *self.tcx),
         })
     }
 }