Rollup of 11 pull requests

Cargo.lock

@@ -154,7 +154,7 @@ version = "0.2.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d9b39be18770d11421cdb1b9947a45dd3f37e93092cbf377614828a319d5fee8"
 dependencies = [
- "hermit-abi",
+ "hermit-abi 0.1.19",
  "libc",
  "winapi",
 ]
@@ -1610,6 +1610,15 @@ name = "hermit-abi"
 version = "0.1.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "62b467343b94ba476dcb2500d242dadbb39557df889310ac77c5d99100aaac33"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "hermit-abi"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1ab7905ea95c6d9af62940f9d7dd9596d54c334ae2c15300c482051292d5637f"
 dependencies = [
  "compiler_builtins",
  "libc",
@@ -2396,7 +2405,7 @@ version = "1.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "19e64526ebdee182341572e50e9ad03965aa510cd94427a4549448f285e957a1"
 dependencies = [
- "hermit-abi",
+ "hermit-abi 0.1.19",
  "libc",
 ]
 
@@ -4782,7 +4791,7 @@ dependencies = [
  "dlmalloc",
  "fortanix-sgx-abi",
  "hashbrown 0.12.0",
- "hermit-abi",
+ "hermit-abi 0.2.0",
  "libc",
  "miniz_oxide",
  "object 0.26.2",

compiler/rustc_const_eval/src/const_eval/mod.rs

@@ -147,6 +147,10 @@ pub(crate) fn try_destructure_const<'tcx>(
     // We go to `usize` as we cannot allocate anything bigger anyway.
     let (field_count, variant, down) = match val.ty().kind() {
         ty::Array(_, len) => (usize::try_from(len.eval_usize(tcx, param_env)).unwrap(), None, op),
+        // Checks if we have any variants, to avoid downcasting to a non-existing variant (when
+        // there are no variants `read_discriminant` successfully returns a non-existing variant
+        // index).
+        ty::Adt(def, _) if def.variants.is_empty() => throw_ub!(Unreachable),
         ty::Adt(def, _) => {
             let variant = ecx.read_discriminant(&op)?.1;
             let down = ecx.operand_downcast(&op, variant)?;

compiler/rustc_index/src/lib.rs

@@ -9,3 +9,5 @@
 pub mod bit_set;
 pub mod interval;
 pub mod vec;
+
+pub use rustc_macros::newtype_index;