fix ICE in ConstProp

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -14,7 +14,7 @@ use rustc_middle::mir::AssertMessage;
 use rustc_session::Limit;
 use rustc_span::symbol::{sym, Symbol};
 use rustc_target::abi::{Align, Size};
-use rustc_target::spec::abi::Abi;
+use rustc_target::spec::abi::Abi as CallAbi;
 
 use crate::interpret::{
     self, compile_time_machine, AllocId, ConstAllocation, Frame, ImmTy, InterpCx, InterpResult,
@@ -263,7 +263,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
     fn find_mir_or_eval_fn(
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
         instance: ty::Instance<'tcx>,
-        _abi: Abi,
+        _abi: CallAbi,
         args: &[OpTy<'tcx>],
         _dest: &PlaceTy<'tcx>,
         _ret: Option<mir::BasicBlock>,

compiler/rustc_const_eval/src/interpret/machine.rs

@@ -10,7 +10,7 @@ use rustc_middle::mir;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::def_id::DefId;
 use rustc_target::abi::Size;
-use rustc_target::spec::abi::Abi;
+use rustc_target::spec::abi::Abi as CallAbi;
 
 use super::{
     AllocId, AllocRange, Allocation, ConstAllocation, Frame, ImmTy, InterpCx, InterpResult,
@@ -139,7 +139,7 @@ pub trait Machine<'mir, 'tcx>: Sized {
     /// Whether to enforce integers and floats not having provenance.
     fn enforce_number_no_provenance(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool;
 
-    /// Whether function calls should be [ABI](Abi)-checked.
+    /// Whether function calls should be [ABI](CallAbi)-checked.
     fn enforce_abi(_ecx: &InterpCx<'mir, 'tcx, Self>) -> bool {
         true
     }
@@ -170,7 +170,7 @@ pub trait Machine<'mir, 'tcx>: Sized {
     fn find_mir_or_eval_fn(
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
         instance: ty::Instance<'tcx>,
-        abi: Abi,
+        abi: CallAbi,
         args: &[OpTy<'tcx, Self::PointerTag>],
         destination: &PlaceTy<'tcx, Self::PointerTag>,
         target: Option<mir::BasicBlock>,
@@ -182,7 +182,7 @@ pub trait Machine<'mir, 'tcx>: Sized {
     fn call_extra_fn(
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
         fn_val: Self::ExtraFnVal,
-        abi: Abi,
+        abi: CallAbi,
         args: &[OpTy<'tcx, Self::PointerTag>],
         destination: &PlaceTy<'tcx, Self::PointerTag>,
         target: Option<mir::BasicBlock>,
@@ -480,7 +480,7 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
     fn call_extra_fn(
         _ecx: &mut InterpCx<$mir, $tcx, Self>,
         fn_val: !,
-        _abi: Abi,
+        _abi: CallAbi,
         _args: &[OpTy<$tcx>],
         _destination: &PlaceTy<$tcx, Self::PointerTag>,
         _target: Option<mir::BasicBlock>,

compiler/rustc_const_eval/src/interpret/operand.rs

@@ -71,6 +71,7 @@ impl<'tcx, Tag: Provenance> Immediate<Tag> {
     }
 
     #[inline]
+    #[cfg_attr(debug_assertions, track_caller)] // only in debug builds due to perf (see #98980)
     pub fn to_scalar_or_uninit(self) -> ScalarMaybeUninit<Tag> {
         match self {
             Immediate::Scalar(val) => val,
@@ -79,11 +80,13 @@ impl<'tcx, Tag: Provenance> Immediate<Tag> {
     }
 
     #[inline]
+    #[cfg_attr(debug_assertions, track_caller)] // only in debug builds due to perf (see #98980)
     pub fn to_scalar(self) -> InterpResult<'tcx, Scalar<Tag>> {
         self.to_scalar_or_uninit().check_init()
     }
 
     #[inline]
+    #[cfg_attr(debug_assertions, track_caller)] // only in debug builds due to perf (see #98980)
     pub fn to_scalar_or_uninit_pair(self) -> (ScalarMaybeUninit<Tag>, ScalarMaybeUninit<Tag>) {
         match self {
             Immediate::ScalarPair(val1, val2) => (val1, val2),
@@ -92,6 +95,7 @@ impl<'tcx, Tag: Provenance> Immediate<Tag> {
     }
 
     #[inline]
+    #[cfg_attr(debug_assertions, track_caller)] // only in debug builds due to perf (see #98980)
     pub fn to_scalar_pair(self) -> InterpResult<'tcx, (Scalar<Tag>, Scalar<Tag>)> {
         let (val1, val2) = self.to_scalar_or_uninit_pair();
         Ok((val1.check_init()?, val2.check_init()?))

compiler/rustc_mir_transform/src/const_prop.rs

@@ -22,8 +22,8 @@ use rustc_middle::ty::{
     self, ConstKind, EarlyBinder, Instance, ParamEnv, Ty, TyCtxt, TypeVisitable,
 };
 use rustc_span::{def_id::DefId, Span};
-use rustc_target::abi::{HasDataLayout, Size, TargetDataLayout};
-use rustc_target::spec::abi::Abi;
+use rustc_target::abi::{self, HasDataLayout, Size, TargetDataLayout};
+use rustc_target::spec::abi::Abi as CallAbi;
 use rustc_trait_selection::traits;
 
 use crate::MirPass;
@@ -199,7 +199,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for ConstPropMachine<'mir, 'tcx>
     fn find_mir_or_eval_fn(
         _ecx: &mut InterpCx<'mir, 'tcx, Self>,
         _instance: ty::Instance<'tcx>,
-        _abi: Abi,
+        _abi: CallAbi,
         _args: &[OpTy<'tcx>],
         _destination: &PlaceTy<'tcx>,
         _target: Option<BasicBlock>,
@@ -654,6 +654,11 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                     (Ok(_), Ok(_)) => return this.ecx.eval_rvalue_into_place(rvalue, place),
                 };
 
+                if !matches!(const_arg.layout.abi, abi::Abi::Scalar(..)) {
+                    // We cannot handle Scalar Pair stuff.
+                    return this.ecx.eval_rvalue_into_place(rvalue, place);
+                }
+
                 let arg_value = const_arg.to_scalar()?.to_bits(const_arg.layout.size)?;
                 let dest = this.ecx.eval_place(place)?;
 

compiler/rustc_mir_transform/src/const_prop_lint.rs

@@ -24,7 +24,7 @@ use rustc_middle::ty::{
 use rustc_session::lint;
 use rustc_span::{def_id::DefId, Span};
 use rustc_target::abi::{HasDataLayout, Size, TargetDataLayout};
-use rustc_target::spec::abi::Abi;
+use rustc_target::spec::abi::Abi as CallAbi;
 use rustc_trait_selection::traits;
 
 use crate::MirLint;
@@ -191,7 +191,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for ConstPropMachine<'mir, 'tcx>
     fn find_mir_or_eval_fn(
         _ecx: &mut InterpCx<'mir, 'tcx, Self>,
         _instance: ty::Instance<'tcx>,
-        _abi: Abi,
+        _abi: CallAbi,
         _args: &[OpTy<'tcx>],
         _destination: &PlaceTy<'tcx>,
         _target: Option<BasicBlock>,

src/test/ui/consts/issue-96169.rs

@@ -0,0 +1,18 @@
+// check-pass
+// compile-flags: -Zmir-opt-level=4 --emit=mir
+#![allow(unused)]
+fn a() -> usize { 0 }
+
+fn bar(_: u32) {}
+
+fn baz() -> *const dyn Fn(u32) { unimplemented!() }
+
+fn foo() {
+    match () {
+        _ if baz() == &bar as &dyn Fn(u32) => (),
+        () => (),
+    }
+}
+
+fn main() {
+}