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Guard against non-monomorphized type_id intrinsic call #74538

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Jul 23, 2020
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12 changes: 10 additions & 2 deletions src/librustc_mir/interpret/intrinsics.rs
Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ use rustc_middle::mir::{
};
use rustc_middle::ty;
use rustc_middle::ty::subst::SubstsRef;
use rustc_middle::ty::{Ty, TyCtxt};
use rustc_middle::ty::{Ty, TyCtxt, TypeFoldable};
use rustc_span::symbol::{sym, Symbol};
use rustc_target::abi::{Abi, LayoutOf as _, Primitive, Size};

Expand Down Expand Up @@ -54,6 +54,9 @@ crate fn eval_nullary_intrinsic<'tcx>(
let name = tcx.item_name(def_id);
Ok(match name {
sym::type_name => {
if tp_ty.needs_subst() {
throw_inval!(TooGeneric);
}
let alloc = type_name::alloc_type_name(tcx, tp_ty);
ConstValue::Slice { data: alloc, start: 0, end: alloc.len() }
}
Expand All @@ -68,7 +71,12 @@ crate fn eval_nullary_intrinsic<'tcx>(
};
ConstValue::from_machine_usize(n, &tcx)
}
sym::type_id => ConstValue::from_u64(tcx.type_id_hash(tp_ty)),
sym::type_id => {
if tp_ty.needs_subst() {
throw_inval!(TooGeneric);
}
ConstValue::from_u64(tcx.type_id_hash(tp_ty))
}
sym::variant_count => {
if let ty::Adt(ref adt, _) = tp_ty.kind {
ConstValue::from_machine_usize(adt.variants.len() as u64, &tcx)
Expand Down
26 changes: 26 additions & 0 deletions src/test/ui/consts/issue-73976.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,26 @@
// This test is from #73976. We previously did not check if a type is monomorphized
// before calculating its type id, which leads to the bizzare behaviour below that
// TypeId of a generic type does not match itself.
//
// This test case should either run-pass or be rejected at compile time.
// Currently we just disallow this usage and require pattern is monomorphic.

#![feature(const_type_id)]

use std::any::TypeId;

pub struct GetTypeId<T>(T);

impl<T: 'static> GetTypeId<T> {
pub const VALUE: TypeId = TypeId::of::<T>();
}

const fn check_type_id<T: 'static>() -> bool {
matches!(GetTypeId::<T>::VALUE, GetTypeId::<T>::VALUE)
//~^ ERROR could not evaluate constant pattern
//~| ERROR could not evaluate constant pattern
}

fn main() {
assert!(check_type_id::<usize>());
}
14 changes: 14 additions & 0 deletions src/test/ui/consts/issue-73976.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,14 @@
error: could not evaluate constant pattern
--> $DIR/issue-73976.rs:19:37
|
LL | matches!(GetTypeId::<T>::VALUE, GetTypeId::<T>::VALUE)
| ^^^^^^^^^^^^^^^^^^^^^

error: could not evaluate constant pattern
--> $DIR/issue-73976.rs:19:37
|
LL | matches!(GetTypeId::<T>::VALUE, GetTypeId::<T>::VALUE)
| ^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 2 previous errors