Fix foreign type handling

src/base.rs

@@ -365,6 +365,7 @@ fn trans_stmt<'tcx>(
                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
                     let operand = trans_operand(fx, operand);
                     let from_ty = operand.layout().ty;
+                    let to_ty = fx.monomorphize(to_ty);
 
                     fn is_fat_ptr<'tcx>(
                         fx: &FunctionCx<'_, 'tcx, impl Backend>,
@@ -375,9 +376,7 @@ fn trans_stmt<'tcx>(
                                 |ty::TypeAndMut {
                                      ty: pointee_ty,
                                      mutbl: _,
-                                 }| {
+                                 }| has_ptr_meta(fx.tcx, pointee_ty),
-                                    fx.layout_of(pointee_ty).is_unsized()
-                                },
                             )
                             .unwrap_or(false)
                     }

src/common.rs

@@ -60,11 +60,11 @@ pub fn clif_type_from_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Option<types:
             FloatTy::F64 => types::F64,
         },
         ty::FnPtr(_) => pointer_ty(tcx),
-        ty::RawPtr(TypeAndMut { ty, mutbl: _ }) | ty::Ref(_, ty, _) => {
+        ty::RawPtr(TypeAndMut { ty: pointee_ty, mutbl: _ }) | ty::Ref(_, pointee_ty, _) => {
-            if ty.is_sized(tcx.at(DUMMY_SP), ParamEnv::reveal_all()) {
+            if has_ptr_meta(tcx, pointee_ty) {
-                pointer_ty(tcx)
-            } else {
                 return None;
+            } else {
+                pointer_ty(tcx)
             }
         }
         ty::Param(_) => bug!("ty param {:?}", ty),
@@ -72,6 +72,16 @@ pub fn clif_type_from_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Option<types:
     })
 }
 
+/// Is a pointer to this type a fat ptr?
+pub fn has_ptr_meta<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> bool {
+    let ptr_ty = tcx.mk_ptr(TypeAndMut { ty, mutbl: rustc::hir::Mutability::MutImmutable });
+    match &tcx.layout_of(ParamEnv::reveal_all().and(ptr_ty)).unwrap().abi {
+        Abi::Scalar(_) => false,
+        Abi::ScalarPair(_, _) => true,
+        abi => unreachable!("Abi of ptr to {:?} is {:?}???", ty, abi),
+    }
+}
+
 pub fn codegen_select(bcx: &mut FunctionBuilder, cond: Value, lhs: Value, rhs: Value) -> Value {
     let lhs_ty = bcx.func.dfg.value_type(lhs);
     let rhs_ty = bcx.func.dfg.value_type(rhs);

src/num.rs

@@ -347,14 +347,9 @@ pub fn trans_ptr_binop<'tcx>(
     in_lhs: CValue<'tcx>,
     in_rhs: CValue<'tcx>,
 ) -> CValue<'tcx> {
-    let not_fat = match in_lhs.layout().ty.sty {
+    let pointee_ty = in_lhs.layout().ty.builtin_deref(true).unwrap().ty;
-        ty::RawPtr(TypeAndMut { ty, mutbl: _ }) => {
+
-            ty.is_sized(fx.tcx.at(DUMMY_SP), ParamEnv::reveal_all())
+    if !has_ptr_meta(fx.tcx, pointee_ty) {
-        }
-        ty::FnPtr(..) => true,
-        _ => bug!("trans_ptr_binop on non ptr"),
-    };
-    if not_fat {
         match bin_op {
             BinOp::Eq | BinOp::Lt | BinOp::Le | BinOp::Ne | BinOp::Ge | BinOp::Gt => {
                 let lhs = in_lhs.load_scalar(fx);
@@ -364,7 +359,6 @@ pub fn trans_ptr_binop<'tcx>(
             }
             BinOp::Offset => {
                 let (base, offset) = (in_lhs, in_rhs.load_scalar(fx));
-                let pointee_ty = base.layout().ty.builtin_deref(true).unwrap().ty;
                 let pointee_size = fx.layout_of(pointee_ty).size.bytes();
                 let ptr_diff = fx.bcx.ins().imul_imm(offset, pointee_size as i64);
                 let base_val = base.load_scalar(fx);

src/value_and_place.rs

@@ -136,7 +136,7 @@ impl<'tcx> CValue<'tcx> {
             CValueInner::ByRef(addr) => {
                 let (a_scalar, b_scalar) = match &layout.abi {
                     layout::Abi::ScalarPair(a, b) => (a, b),
-                    _ => unreachable!(),
+                    _ => unreachable!("load_scalar_pair({:?})", self),
                 };
                 let b_offset = scalar_pair_calculate_b_offset(fx.tcx, a_scalar, b_scalar);
                 let clif_ty1 = scalar_to_clif_type(fx.tcx, a_scalar.clone());
@@ -496,19 +496,16 @@ impl<'tcx> CPlace<'tcx> {
 
     pub fn place_deref(self, fx: &mut FunctionCx<'_, 'tcx, impl Backend>) -> CPlace<'tcx> {
         let inner_layout = fx.layout_of(self.layout().ty.builtin_deref(true).unwrap().ty);
-        if !inner_layout.is_unsized() {
+        if has_ptr_meta(fx.tcx, inner_layout.ty) {
-            CPlace::for_addr(self.to_cvalue(fx).load_scalar(fx), inner_layout)
-        } else {
             let (addr, extra) = self.to_cvalue(fx).load_scalar_pair(fx);
             CPlace::for_addr_with_extra(addr, extra, inner_layout)
+        } else {
+            CPlace::for_addr(self.to_cvalue(fx).load_scalar(fx), inner_layout)
         }
     }
 
     pub fn write_place_ref(self, fx: &mut FunctionCx<'_, 'tcx, impl Backend>, dest: CPlace<'tcx>) {
-        if !self.layout().is_unsized() {
+        if has_ptr_meta(fx.tcx, self.layout().ty) {
-            let ptr = CValue::by_val(self.to_addr(fx), dest.layout());
-            dest.write_cvalue(fx, ptr);
-        } else {
             let (value, extra) = self.to_addr_maybe_unsized(fx);
             let ptr = CValue::by_val_pair(
                 value,
@@ -516,6 +513,9 @@ impl<'tcx> CPlace<'tcx> {
                 dest.layout(),
             );
             dest.write_cvalue(fx, ptr);
+        } else {
+            let ptr = CValue::by_val(self.to_addr(fx), dest.layout());
+            dest.write_cvalue(fx, ptr);
         }
     }