diff --git a/src/librustc/mir/interpret/allocation.rs b/src/librustc/mir/interpret/allocation.rs
index 00f90800794..b8686754fa7 100644
--- a/src/librustc/mir/interpret/allocation.rs
+++ b/src/librustc/mir/interpret/allocation.rs
@@ -244,7 +244,7 @@ impl<'tcx, Tag: Copy, Extra: AllocationExtra<Tag>> Allocation<Tag, Extra> {
                 Ok(&self.get_bytes(cx, ptr, size_with_null)?[..size])
             }
             // This includes the case where `offset` is out-of-bounds to begin with.
-            None => throw_err!(UnterminatedCString(ptr.erase_tag())),
+            None => throw_err_unsup!(UnterminatedCString(ptr.erase_tag())),
         }
     }
 
@@ -446,7 +446,7 @@ impl<'tcx, Tag: Copy, Extra> Allocation<Tag, Extra> {
         if self.relocations(cx, ptr, size).is_empty() {
             Ok(())
         } else {
-            throw_err!(ReadPointerAsBytes)
+            throw_err_unsup!(ReadPointerAsBytes)
         }
     }
 
@@ -516,7 +516,7 @@ impl<'tcx, Tag, Extra> Allocation<Tag, Extra> {
         self.undef_mask.is_range_defined(
             ptr.offset,
             ptr.offset + size,
-        ).or_else(|idx| throw_err!(ReadUndefBytes(idx)))
+        ).or_else(|idx| throw_err_unsup!(ReadUndefBytes(idx)))
     }
 
     pub fn mark_definedness(
diff --git a/src/librustc/mir/interpret/error.rs b/src/librustc/mir/interpret/error.rs
index 183298ee3f1..7108f69d39e 100644
--- a/src/librustc/mir/interpret/error.rs
+++ b/src/librustc/mir/interpret/error.rs
@@ -184,8 +184,8 @@ pub fn struct_error<'tcx>(tcx: TyCtxtAt<'tcx>, msg: &str) -> DiagnosticBuilder<'
 /// Packages the kind of error we got from the const code interpreter
 /// up with a Rust-level backtrace of where the error occured.
 /// Thsese should always be constructed by calling `.into()` on
-/// a `InterpError`. In `librustc_mir::interpret`, we have the `throw_err!`
-/// macro for this.
+/// a `InterpError`. In `librustc_mir::interpret`, we have `throw_err_*`
+/// macros for this.
 #[derive(Debug, Clone)]
 pub struct InterpErrorInfo<'tcx> {
     pub kind: InterpError<'tcx>,
diff --git a/src/librustc/mir/interpret/mod.rs b/src/librustc/mir/interpret/mod.rs
index 6e8e56a1b11..bc72050de18 100644
--- a/src/librustc/mir/interpret/mod.rs
+++ b/src/librustc/mir/interpret/mod.rs
@@ -1,7 +1,7 @@
 //! An interpreter for MIR used in CTFE and by miri
 
 #[macro_export]
-macro_rules! throw_err {
+macro_rules! throw_err_unsup {
     ($($tt:tt)*) => {
         Err($crate::mir::interpret::InterpError::Unsupported(
             $crate::mir::interpret::UnsupportedOpInfo::$($tt)*
@@ -55,7 +55,7 @@ macro_rules! err_inval {
 }
 
 #[macro_export]
-macro_rules! err {
+macro_rules! err_unsup {
     ($($tt:tt)*) => {
         $crate::mir::interpret::InterpError::Unsupported(
             $crate::mir::interpret::UnsupportedOpInfo::$($tt)*
diff --git a/src/librustc/mir/interpret/pointer.rs b/src/librustc/mir/interpret/pointer.rs
index 27a41bba4c1..17f963609f6 100644
--- a/src/librustc/mir/interpret/pointer.rs
+++ b/src/librustc/mir/interpret/pointer.rs
@@ -196,7 +196,7 @@ impl<'tcx, Tag> Pointer<Tag> {
         msg: CheckInAllocMsg,
     ) -> InterpResult<'tcx, ()> {
         if self.offset > allocation_size {
-            throw_err!(PointerOutOfBounds { ptr: self.erase_tag(), msg, allocation_size })
+            throw_err_unsup!(PointerOutOfBounds { ptr: self.erase_tag(), msg, allocation_size })
         } else {
             Ok(())
         }
diff --git a/src/librustc/mir/interpret/value.rs b/src/librustc/mir/interpret/value.rs
index 9379054bdfc..01db0e48e21 100644
--- a/src/librustc/mir/interpret/value.rs
+++ b/src/librustc/mir/interpret/value.rs
@@ -360,7 +360,7 @@ impl<'tcx, Tag> Scalar<Tag> {
                 Scalar::check_data(data, size);
                 Ok(data)
             }
-            Scalar::Ptr(_) => throw_err!(ReadPointerAsBytes),
+            Scalar::Ptr(_) => throw_err_unsup!(ReadPointerAsBytes),
         }
     }
 
@@ -373,8 +373,8 @@ impl<'tcx, Tag> Scalar<Tag> {
     #[inline]
     pub fn to_ptr(self) -> InterpResult<'tcx, Pointer<Tag>> {
         match self {
-            Scalar::Raw { data: 0, .. } => throw_err!(InvalidNullPointerUsage),
-            Scalar::Raw { .. } => throw_err!(ReadBytesAsPointer),
+            Scalar::Raw { data: 0, .. } => throw_err_unsup!(InvalidNullPointerUsage),
+            Scalar::Raw { .. } => throw_err_unsup!(ReadBytesAsPointer),
             Scalar::Ptr(p) => Ok(p),
         }
     }
@@ -406,7 +406,7 @@ impl<'tcx, Tag> Scalar<Tag> {
         match self {
             Scalar::Raw { data: 0, size: 1 } => Ok(false),
             Scalar::Raw { data: 1, size: 1 } => Ok(true),
-            _ => throw_err!(InvalidBool),
+            _ => throw_err_unsup!(InvalidBool),
         }
     }
 
@@ -414,7 +414,7 @@ impl<'tcx, Tag> Scalar<Tag> {
         let val = self.to_u32()?;
         match ::std::char::from_u32(val) {
             Some(c) => Ok(c),
-            None => throw_err!(InvalidChar(val as u128)),
+            None => throw_err_unsup!(InvalidChar(val as u128)),
         }
     }
 
@@ -537,7 +537,7 @@ impl<'tcx, Tag> ScalarMaybeUndef<Tag> {
     pub fn not_undef(self) -> InterpResult<'static, Scalar<Tag>> {
         match self {
             ScalarMaybeUndef::Scalar(scalar) => Ok(scalar),
-            ScalarMaybeUndef::Undef => throw_err!(ReadUndefBytes(Size::from_bytes(0))),
+            ScalarMaybeUndef::Undef => throw_err_unsup!(ReadUndefBytes(Size::from_bytes(0))),
         }
     }
 
diff --git a/src/librustc_mir/const_eval.rs b/src/librustc_mir/const_eval.rs
index 786e2e71ec6..423449bc95d 100644
--- a/src/librustc_mir/const_eval.rs
+++ b/src/librustc_mir/const_eval.rs
@@ -352,7 +352,9 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
                     ecx.goto_block(ret)?; // fully evaluated and done
                     Ok(None)
                 } else {
-                    throw_err!(MachineError(format!("calling non-const function `{}`", instance)))
+                    throw_err_unsup!(
+                        MachineError(format!("calling non-const function `{}`", instance))
+                    )
                 };
             }
         }
@@ -412,7 +414,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
         _tcx: TyCtxt<'tcx>,
         _def_id: DefId,
     ) -> InterpResult<'tcx, Cow<'tcx, Allocation<Self::PointerTag>>> {
-        throw_err!(ReadForeignStatic)
+        throw_err_unsup!(ReadForeignStatic)
     }
 
     #[inline(always)]
diff --git a/src/librustc_mir/interpret/cast.rs b/src/librustc_mir/interpret/cast.rs
index fb0ad26d566..94f3148aaaf 100644
--- a/src/librustc_mir/interpret/cast.rs
+++ b/src/librustc_mir/interpret/cast.rs
@@ -199,7 +199,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             },
 
             // Casts to bool are not permitted by rustc, no need to handle them here.
-            _ => throw_err!(Unimplemented(format!("int to {:?} cast", dest_layout.ty))),
+            _ => throw_err_unsup!(Unimplemented(format!("int to {:?} cast", dest_layout.ty))),
         }
     }
 
diff --git a/src/librustc_mir/interpret/eval_context.rs b/src/librustc_mir/interpret/eval_context.rs
index 61ebcb58b91..61ee60fd3d5 100644
--- a/src/librustc_mir/interpret/eval_context.rs
+++ b/src/librustc_mir/interpret/eval_context.rs
@@ -135,7 +135,7 @@ pub enum LocalValue<Tag=(), Id=AllocId> {
 impl<'tcx, Tag: Copy + 'static> LocalState<'tcx, Tag> {
     pub fn access(&self) -> InterpResult<'tcx, Operand<Tag>> {
         match self.value {
-            LocalValue::Dead => throw_err!(DeadLocal),
+            LocalValue::Dead => throw_err_unsup!(DeadLocal),
             LocalValue::Uninitialized =>
                 bug!("The type checker should prevent reading from a never-written local"),
             LocalValue::Live(val) => Ok(val),
@@ -148,7 +148,7 @@ impl<'tcx, Tag: Copy + 'static> LocalState<'tcx, Tag> {
         &mut self,
     ) -> InterpResult<'tcx, Result<&mut LocalValue<Tag>, MemPlace<Tag>>> {
         match self.value {
-            LocalValue::Dead => throw_err!(DeadLocal),
+            LocalValue::Dead => throw_err_unsup!(DeadLocal),
             LocalValue::Live(Operand::Indirect(mplace)) => Ok(Err(mplace)),
             ref mut local @ LocalValue::Live(Operand::Immediate(_)) |
             ref mut local @ LocalValue::Uninitialized => {
@@ -346,7 +346,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             ty::InstanceDef::Item(def_id) => if self.tcx.is_mir_available(did) {
                 Ok(self.tcx.optimized_mir(did))
             } else {
-                throw_err!(NoMirFor(self.tcx.def_path_str(def_id)))
+                throw_err_unsup!(NoMirFor(self.tcx.def_path_str(def_id)))
             },
             _ => Ok(self.tcx.instance_mir(instance)),
         }
diff --git a/src/librustc_mir/interpret/intern.rs b/src/librustc_mir/interpret/intern.rs
index a47cea9a70a..4539a1c7e1d 100644
--- a/src/librustc_mir/interpret/intern.rs
+++ b/src/librustc_mir/interpret/intern.rs
@@ -328,7 +328,7 @@ pub fn intern_const_alloc_recursive(
             }
         } else if ecx.memory().dead_alloc_map.contains_key(&alloc_id) {
             // dangling pointer
-            return throw_err!(
+            return throw_err_unsup!(
                 ValidationFailure("encountered dangling pointer in final constant".into())
             )
         }
diff --git a/src/librustc_mir/interpret/intrinsics.rs b/src/librustc_mir/interpret/intrinsics.rs
index d571d90e896..687265c983f 100644
--- a/src/librustc_mir/interpret/intrinsics.rs
+++ b/src/librustc_mir/interpret/intrinsics.rs
@@ -104,7 +104,9 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 };
                 let out_val = if intrinsic_name.ends_with("_nonzero") {
                     if bits == 0 {
-                        return throw_err!(Intrinsic(format!("{} called on 0", intrinsic_name)));
+                        return throw_err_unsup!(
+                            Intrinsic(format!("{} called on 0", intrinsic_name))
+                        );
                     }
                     numeric_intrinsic(intrinsic_name.trim_end_matches("_nonzero"), bits, kind)?
                 } else {
@@ -190,7 +192,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 if overflowed {
                     let layout = self.layout_of(substs.type_at(0))?;
                     let r_val =  r.to_scalar()?.to_bits(layout.size)?;
-                    return throw_err!(Intrinsic(
+                    return throw_err_unsup!(Intrinsic(
                         format!("Overflowing shift by {} in {}", r_val, intrinsic_name),
                     ));
                 }
diff --git a/src/librustc_mir/interpret/machine.rs b/src/librustc_mir/interpret/machine.rs
index 5fc43c7712c..3f3d4376d29 100644
--- a/src/librustc_mir/interpret/machine.rs
+++ b/src/librustc_mir/interpret/machine.rs
@@ -251,6 +251,6 @@ pub trait Machine<'mir, 'tcx>: Sized {
         _mem: &Memory<'mir, 'tcx, Self>,
         _ptr: Pointer<Self::PointerTag>,
     ) -> InterpResult<'tcx, u64> {
-        throw_err!(ReadPointerAsBytes)
+        throw_err_unsup!(ReadPointerAsBytes)
     }
 }
diff --git a/src/librustc_mir/interpret/memory.rs b/src/librustc_mir/interpret/memory.rs
index ee5607c4938..8c43fb3dc40 100644
--- a/src/librustc_mir/interpret/memory.rs
+++ b/src/librustc_mir/interpret/memory.rs
@@ -66,7 +66,7 @@ impl<'tcx, Other> FnVal<'tcx, Other> {
         match self {
             FnVal::Instance(instance) =>
                 Ok(instance),
-            FnVal::Other(_) => throw_err!(MachineError(format!(
+            FnVal::Other(_) => throw_err_unsup!(MachineError(format!(
                 "Expected instance function pointer, got 'other' pointer"
             ))),
         }
@@ -202,7 +202,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         kind: MemoryKind<M::MemoryKinds>,
     ) -> InterpResult<'tcx, Pointer<M::PointerTag>> {
         if ptr.offset.bytes() != 0 {
-            return throw_err!(ReallocateNonBasePtr);
+            return throw_err_unsup!(ReallocateNonBasePtr);
         }
 
         // For simplicities' sake, we implement reallocate as "alloc, copy, dealloc".
@@ -243,7 +243,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         trace!("deallocating: {}", ptr.alloc_id);
 
         if ptr.offset.bytes() != 0 {
-            return throw_err!(DeallocateNonBasePtr);
+            return throw_err_unsup!(DeallocateNonBasePtr);
         }
 
         let (alloc_kind, mut alloc) = match self.alloc_map.remove(&ptr.alloc_id) {
@@ -251,22 +251,22 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             None => {
                 // Deallocating static memory -- always an error
                 return match self.tcx.alloc_map.lock().get(ptr.alloc_id) {
-                    Some(GlobalAlloc::Function(..)) => throw_err!(DeallocatedWrongMemoryKind(
+                    Some(GlobalAlloc::Function(..)) => throw_err_unsup!(DeallocatedWrongMemoryKind(
                         "function".to_string(),
                         format!("{:?}", kind),
                     )),
                     Some(GlobalAlloc::Static(..)) |
-                    Some(GlobalAlloc::Memory(..)) => throw_err!(DeallocatedWrongMemoryKind(
+                    Some(GlobalAlloc::Memory(..)) => throw_err_unsup!(DeallocatedWrongMemoryKind(
                         "static".to_string(),
                         format!("{:?}", kind),
                     )),
-                    None => throw_err!(DoubleFree)
+                    None => throw_err_unsup!(DoubleFree)
                 }
             }
         };
 
         if alloc_kind != kind {
-            return throw_err!(DeallocatedWrongMemoryKind(
+            return throw_err_unsup!(DeallocatedWrongMemoryKind(
                 format!("{:?}", alloc_kind),
                 format!("{:?}", kind),
             ));
@@ -274,7 +274,9 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         if let Some((size, align)) = old_size_and_align {
             if size.bytes() != alloc.bytes.len() as u64 || align != alloc.align {
                 let bytes = Size::from_bytes(alloc.bytes.len() as u64);
-                return throw_err!(IncorrectAllocationInformation(size, bytes, align, alloc.align));
+                return throw_err_unsup!(
+                    IncorrectAllocationInformation(size, bytes, align, alloc.align)
+                );
             }
         }
 
@@ -319,7 +321,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             } else {
                 // The biggest power of two through which `offset` is divisible.
                 let offset_pow2 = 1 << offset.trailing_zeros();
-                throw_err!(AlignmentCheckFailed {
+                throw_err_unsup!(AlignmentCheckFailed {
                     has: Align::from_bytes(offset_pow2).unwrap(),
                     required: align,
                 })
@@ -341,7 +343,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
                 assert!(size.bytes() == 0);
                 // Must be non-NULL and aligned.
                 if bits == 0 {
-                    return throw_err!(InvalidNullPointerUsage);
+                    return throw_err_unsup!(InvalidNullPointerUsage);
                 }
                 check_offset_align(bits, align)?;
                 None
@@ -362,7 +364,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
                     // got picked we might be aligned even if this check fails.
                     // We instead have to fall back to converting to an integer and checking
                     // the "real" alignment.
-                    return throw_err!(AlignmentCheckFailed {
+                    return throw_err_unsup!(AlignmentCheckFailed {
                         has: alloc_align,
                         required: align,
                     });
@@ -413,9 +415,9 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             Some(GlobalAlloc::Memory(mem)) =>
                 Cow::Borrowed(mem),
             Some(GlobalAlloc::Function(..)) =>
-                return throw_err!(DerefFunctionPointer),
+                return throw_err_unsup!(DerefFunctionPointer),
             None =>
-                return throw_err!(DanglingPointerDeref),
+                return throw_err_unsup!(DanglingPointerDeref),
             Some(GlobalAlloc::Static(def_id)) => {
                 // We got a "lazy" static that has not been computed yet.
                 if tcx.is_foreign_item(def_id) {
@@ -505,11 +507,11 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             // to give us a cheap reference.
             let alloc = Self::get_static_alloc(memory_extra, tcx, id)?;
             if alloc.mutability == Mutability::Immutable {
-                return throw_err!(ModifiedConstantMemory);
+                return throw_err_unsup!(ModifiedConstantMemory);
             }
             match M::STATIC_KIND {
                 Some(kind) => Ok((MemoryKind::Machine(kind), alloc.into_owned())),
-                None => throw_err!(ModifiedStatic),
+                None => throw_err_unsup!(ModifiedStatic),
             }
         });
         // Unpack the error type manually because type inference doesn't
@@ -519,7 +521,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             Ok(a) => {
                 let a = &mut a.1;
                 if a.mutability == Mutability::Immutable {
-                    return throw_err!(ModifiedConstantMemory);
+                    return throw_err_unsup!(ModifiedConstantMemory);
                 }
                 Ok(a)
             }
@@ -548,7 +550,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         if let Ok(_) = self.get_fn_alloc(id) {
             return if let AllocCheck::Dereferencable = liveness {
                 // The caller requested no function pointers.
-                throw_err!(DerefFunctionPointer)
+                throw_err_unsup!(DerefFunctionPointer)
             } else {
                 Ok((Size::ZERO, Align::from_bytes(1).unwrap()))
             };
@@ -579,7 +581,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
                     .expect("deallocated pointers should all be recorded in \
                             `dead_alloc_map`"))
             } else {
-                throw_err!(DanglingPointerDeref)
+                throw_err_unsup!(DanglingPointerDeref)
             },
         }
     }
@@ -591,7 +593,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         } else {
             match self.tcx.alloc_map.lock().get(id) {
                 Some(GlobalAlloc::Function(instance)) => Ok(FnVal::Instance(instance)),
-                _ => throw_err!(ExecuteMemory),
+                _ => throw_err_unsup!(ExecuteMemory),
             }
         }
     }
@@ -602,7 +604,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
     ) -> InterpResult<'tcx, FnVal<'tcx, M::ExtraFnVal>> {
         let ptr = self.force_ptr(ptr)?; // We definitely need a pointer value.
         if ptr.offset.bytes() != 0 {
-            return throw_err!(InvalidFunctionPointer);
+            return throw_err_unsup!(InvalidFunctionPointer);
         }
         self.get_fn_alloc(ptr.alloc_id)
     }
@@ -837,7 +839,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
                     if (src.offset <= dest.offset && src.offset + size > dest.offset) ||
                         (dest.offset <= src.offset && dest.offset + size > src.offset)
                     {
-                        return throw_err!(Intrinsic(
+                        return throw_err_unsup!(Intrinsic(
                             "copy_nonoverlapping called on overlapping ranges".to_string(),
                         ));
                     }
diff --git a/src/librustc_mir/interpret/operand.rs b/src/librustc_mir/interpret/operand.rs
index 346dd83f1d5..8c443c9579f 100644
--- a/src/librustc_mir/interpret/operand.rs
+++ b/src/librustc_mir/interpret/operand.rs
@@ -461,7 +461,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         mir_place.iterate(|place_base, place_projection| {
             let mut op = match place_base {
                 PlaceBase::Local(mir::RETURN_PLACE) =>
-                    return throw_err!(ReadFromReturnPointer),
+                    return throw_err_unsup!(ReadFromReturnPointer),
                 PlaceBase::Local(local) => {
                     // Do not use the layout passed in as argument if the base we are looking at
                     // here is not the entire place.
@@ -610,7 +610,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 let bits_discr = match raw_discr.to_bits(discr_val.layout.size) {
                     Ok(raw_discr) => raw_discr,
                     Err(_) =>
-                        return throw_err!(InvalidDiscriminant(raw_discr.erase_tag())),
+                        return throw_err_unsup!(InvalidDiscriminant(raw_discr.erase_tag())),
                 };
                 let real_discr = if discr_val.layout.ty.is_signed() {
                     // going from layout tag type to typeck discriminant type
@@ -637,7 +637,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                         .find(|(_, var)| var.val == real_discr),
                     _ => bug!("tagged layout for non-adt non-generator"),
                 }.ok_or_else(
-                    || err!(InvalidDiscriminant(raw_discr.erase_tag()))
+                    || err_unsup!(InvalidDiscriminant(raw_discr.erase_tag()))
                 )?;
                 (real_discr, index.0)
             },
@@ -657,7 +657,9 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                         let ptr_valid = niche_start == 0 && variants_start == variants_end &&
                             !self.memory.ptr_may_be_null(ptr);
                         if !ptr_valid {
-                            return throw_err!(InvalidDiscriminant(raw_discr.erase_tag().into()));
+                            return throw_err_unsup!(
+                                InvalidDiscriminant(raw_discr.erase_tag().into())
+                            );
                         }
                         (dataful_variant.as_u32() as u128, dataful_variant)
                     },
diff --git a/src/librustc_mir/interpret/operator.rs b/src/librustc_mir/interpret/operator.rs
index 5aea423e388..334cf09ba12 100644
--- a/src/librustc_mir/interpret/operator.rs
+++ b/src/librustc_mir/interpret/operator.rs
@@ -155,7 +155,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 r,
                 right_layout.ty
             );
-            return throw_err!(Unimplemented(msg));
+            return throw_err_unsup!(Unimplemented(msg));
         }
 
         // Operations that need special treatment for signed integers
@@ -250,7 +250,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     r,
                     right_layout.ty,
                 );
-                return throw_err!(Unimplemented(msg));
+                return throw_err_unsup!(Unimplemented(msg));
             }
         };
 
diff --git a/src/librustc_mir/interpret/place.rs b/src/librustc_mir/interpret/place.rs
index 4349c99a619..b385862490a 100644
--- a/src/librustc_mir/interpret/place.rs
+++ b/src/librustc_mir/interpret/place.rs
@@ -622,7 +622,7 @@ where
                                 .layout_of(self.monomorphize(self.frame().body.return_ty())?)?,
                         }
                     }
-                    None => return throw_err!(InvalidNullPointerUsage),
+                    None => return throw_err_unsup!(InvalidNullPointerUsage),
                 },
                 PlaceBase::Local(local) => PlaceTy {
                     // This works even for dead/uninitialized locals; we check further when writing
diff --git a/src/librustc_mir/interpret/step.rs b/src/librustc_mir/interpret/step.rs
index 3aa0144fa8f..de798ecee73 100644
--- a/src/librustc_mir/interpret/step.rs
+++ b/src/librustc_mir/interpret/step.rs
@@ -121,7 +121,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             // size of MIR constantly.
             Nop => {}
 
-            InlineAsm { .. } => return throw_err!(InlineAsm),
+            InlineAsm { .. } => return throw_err_unsup!(InlineAsm),
         }
 
         self.stack[frame_idx].stmt += 1;
diff --git a/src/librustc_mir/interpret/terminator.rs b/src/librustc_mir/interpret/terminator.rs
index 53992201081..f1c91058b71 100644
--- a/src/librustc_mir/interpret/terminator.rs
+++ b/src/librustc_mir/interpret/terminator.rs
@@ -89,7 +89,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     },
                     _ => {
                         let msg = format!("can't handle callee of type {:?}", func.layout.ty);
-                        return throw_err!(Unimplemented(msg));
+                        return throw_err_unsup!(Unimplemented(msg));
                     }
                 };
                 let args = self.eval_operands(args)?;
@@ -220,13 +220,15 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             return Ok(());
         }
         let caller_arg = caller_arg.next()
-            .ok_or_else(|| err!(FunctionArgCountMismatch)) ?;
+            .ok_or_else(|| err_unsup!(FunctionArgCountMismatch)) ?;
         if rust_abi {
             debug_assert!(!caller_arg.layout.is_zst(), "ZSTs must have been already filtered out");
         }
         // Now, check
         if !Self::check_argument_compat(rust_abi, caller_arg.layout, callee_arg.layout) {
-            return throw_err!(FunctionArgMismatch(caller_arg.layout.ty, callee_arg.layout.ty));
+            return throw_err_unsup!(
+                FunctionArgMismatch(caller_arg.layout.ty, callee_arg.layout.ty)
+            );
         }
         // We allow some transmutes here
         self.copy_op_transmute(caller_arg, callee_arg)
@@ -254,7 +256,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         match instance.def {
             ty::InstanceDef::Intrinsic(..) => {
                 if caller_abi != Abi::RustIntrinsic {
-                    return throw_err!(FunctionAbiMismatch(caller_abi, Abi::RustIntrinsic));
+                    return throw_err_unsup!(FunctionAbiMismatch(caller_abi, Abi::RustIntrinsic));
                 }
                 // The intrinsic itself cannot diverge, so if we got here without a return
                 // place... (can happen e.g., for transmute returning `!`)
@@ -295,7 +297,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                             abi,
                     };
                     if normalize_abi(caller_abi) != normalize_abi(callee_abi) {
-                        return throw_err!(FunctionAbiMismatch(caller_abi, callee_abi));
+                        return throw_err_unsup!(FunctionAbiMismatch(caller_abi, callee_abi));
                     }
                 }
 
@@ -390,7 +392,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     // Now we should have no more caller args
                     if caller_iter.next().is_some() {
                         trace!("Caller has passed too many args");
-                        return throw_err!(FunctionArgCountMismatch);
+                        return throw_err_unsup!(FunctionArgCountMismatch);
                     }
                     // Don't forget to check the return type!
                     if let Some(caller_ret) = dest {
@@ -402,7 +404,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                             caller_ret.layout,
                             callee_ret.layout,
                         ) {
-                            return throw_err!(
+                            return throw_err_unsup!(
                                 FunctionRetMismatch(caller_ret.layout.ty, callee_ret.layout.ty)
                             );
                         }
@@ -410,7 +412,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                         let local = mir::RETURN_PLACE;
                         let ty = self.frame().body.local_decls[local].ty;
                         if !self.tcx.is_ty_uninhabited_from_any_module(ty) {
-                            return throw_err!(FunctionRetMismatch(self.tcx.types.never, ty));
+                            return throw_err_unsup!(FunctionRetMismatch(self.tcx.types.never, ty));
                         }
                     }
                     Ok(())
diff --git a/src/librustc_mir/interpret/validity.rs b/src/librustc_mir/interpret/validity.rs
index 511ebfd023c..df6fb7a7c63 100644
--- a/src/librustc_mir/interpret/validity.rs
+++ b/src/librustc_mir/interpret/validity.rs
@@ -22,7 +22,7 @@ macro_rules! validation_failure {
         } else {
             format!(" at {}", where_)
         };
-        throw_err!(ValidationFailure(format!(
+        throw_err_unsup!(ValidationFailure(format!(
             "encountered {}{}, but expected {}",
             $what, where_, $details,
         )))
@@ -34,7 +34,7 @@ macro_rules! validation_failure {
         } else {
             format!(" at {}", where_)
         };
-        throw_err!(ValidationFailure(format!(
+        throw_err_unsup!(ValidationFailure(format!(
             "encountered {}{}",
             $what, where_,
         )))