Begin nightly-ifying rustc_type_ir

Cargo.lock

@@ -4005,11 +4005,22 @@ name = "rustc_index"
 version = "0.0.0"
 dependencies = [
  "arrayvec",
+ "rustc_index_macros",
  "rustc_macros",
  "rustc_serialize",
  "smallvec",
 ]
 
+[[package]]
+name = "rustc_index_macros"
+version = "0.0.0"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.29",
+ "synstructure 0.13.0",
+]
+
 [[package]]
 name = "rustc_infer"
 version = "0.0.0"

compiler/rustc_index/Cargo.toml

@@ -8,9 +8,10 @@ edition = "2021"
 [dependencies]
 arrayvec = { version = "0.7", default-features = false }
 rustc_serialize = { path = "../rustc_serialize", optional = true }
+rustc_index_macros = { path = "../rustc_index_macros", default-features = false }
 rustc_macros = { path = "../rustc_macros", optional = true }
 smallvec = "1.8.1"
 
 [features]
 default = ["nightly"]
-nightly = ["rustc_serialize", "rustc_macros"]
+nightly = ["rustc_serialize", "rustc_macros", "rustc_index_macros/nightly"]

compiler/rustc_index/src/lib.rs

@@ -25,8 +25,7 @@ mod vec;
 
 pub use {idx::Idx, slice::IndexSlice, vec::IndexVec};
 
-#[cfg(feature = "rustc_macros")]
-pub use rustc_macros::newtype_index;
+pub use rustc_index_macros::newtype_index;
 
 /// Type size assertion. The first argument is a type and the second argument is its expected size.
 ///

compiler/rustc_index/src/vec/tests.rs

@@ -3,7 +3,7 @@
 // Allows the macro invocation below to work
 use crate as rustc_index;
 
-rustc_macros::newtype_index! {
+crate::newtype_index! {
     #[max = 0xFFFF_FFFA]
     struct MyIdx {}
 }

compiler/rustc_index_macros/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "rustc_index_macros"
+version = "0.0.0"
+edition = "2021"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+synstructure = "0.13.0"
+syn = { version = "2.0.9", features = ["full"] }
+proc-macro2 = "1"
+quote = "1"
+
+[features]
+default = ["nightly"]
+nightly = []

compiler/rustc_index_macros/src/lib.rs

@@ -0,0 +1,30 @@
+#![cfg_attr(feature = "nightly", feature(allow_internal_unstable))]
+#![cfg_attr(feature = "nightly", allow(internal_features))]
+
+use proc_macro::TokenStream;
+
+mod newtype;
+
+/// Creates a struct type `S` that can be used as an index with
+/// `IndexVec` and so on.
+///
+/// There are two ways of interacting with these indices:
+///
+/// - The `From` impls are the preferred way. So you can do
+///   `S::from(v)` with a `usize` or `u32`. And you can convert back
+///   to an integer with `u32::from(s)`.
+///
+/// - Alternatively, you can use the methods `S::new(v)` and `s.index()`
+///   to create/return a value.
+///
+/// Internally, the index uses a u32, so the index must not exceed
+/// `u32::MAX`. You can also customize things like the `Debug` impl,
+/// what traits are derived, and so forth via the macro.
+#[proc_macro]
+#[cfg_attr(
+    feature = "nightly",
+    allow_internal_unstable(step_trait, rustc_attrs, trusted_step, spec_option_partial_eq)
+)]
+pub fn newtype_index(input: TokenStream) -> TokenStream {
+    newtype::newtype(input)
+}

compiler/rustc_macros/src/newtype.rs → compiler/rustc_index_macros/src/newtype.rs

@@ -24,9 +24,16 @@ impl Parse for Newtype {
         let mut consts = Vec::new();
         let mut encodable = true;
         let mut ord = true;
+        let mut gate_rustc_only = quote! {};
+        let mut gate_rustc_only_cfg = quote! { all() };
 
         attrs.retain(|attr| match attr.path().get_ident() {
             Some(ident) => match &*ident.to_string() {
+                "gate_rustc_only" => {
+                    gate_rustc_only = quote! { #[cfg(feature = "nightly")] };
+                    gate_rustc_only_cfg = quote! { feature = "nightly" };
+                    false
+                }
                 "custom_encodable" => {
                     encodable = false;
                     false
@@ -88,11 +95,13 @@ impl Parse for Newtype {
 
         let encodable_impls = if encodable {
             quote! {
+                #gate_rustc_only
                 impl<D: ::rustc_serialize::Decoder> ::rustc_serialize::Decodable<D> for #name {
                     fn decode(d: &mut D) -> Self {
                         Self::from_u32(d.read_u32())
                     }
                 }
+                #gate_rustc_only
                 impl<E: ::rustc_serialize::Encoder> ::rustc_serialize::Encodable<E> for #name {
                     fn encode(&self, e: &mut E) {
                         e.emit_u32(self.private);
@@ -110,6 +119,7 @@ impl Parse for Newtype {
 
         let step = if ord {
             quote! {
+                #gate_rustc_only
                 impl ::std::iter::Step for #name {
                     #[inline]
                     fn steps_between(start: &Self, end: &Self) -> Option<usize> {
@@ -131,6 +141,7 @@ impl Parse for Newtype {
                 }
 
                 // Safety: The implementation of `Step` upholds all invariants.
+                #gate_rustc_only
                 unsafe impl ::std::iter::TrustedStep for #name {}
             }
         } else {
@@ -148,6 +159,7 @@ impl Parse for Newtype {
         let spec_partial_eq_impl = if let Lit::Int(max) = &max {
             if let Ok(max_val) = max.base10_parse::<u32>() {
                 quote! {
+                    #gate_rustc_only
                     impl core::option::SpecOptionPartialEq for #name {
                         #[inline]
                         fn eq(l: &Option<Self>, r: &Option<Self>) -> bool {
@@ -173,8 +185,8 @@ impl Parse for Newtype {
         Ok(Self(quote! {
             #(#attrs)*
             #[derive(Clone, Copy, PartialEq, Eq, Hash, #(#derive_paths),*)]
-            #[rustc_layout_scalar_valid_range_end(#max)]
-            #[rustc_pass_by_value]
+            #[cfg_attr(#gate_rustc_only_cfg, rustc_layout_scalar_valid_range_end(#max))]
+            #[cfg_attr(#gate_rustc_only_cfg, rustc_pass_by_value)]
             #vis struct #name {
                 private: u32,
             }

compiler/rustc_macros/src/lib.rs

@@ -17,7 +17,6 @@ use proc_macro::TokenStream;
 mod diagnostics;
 mod hash_stable;
 mod lift;
-mod newtype;
 mod query;
 mod serialize;
 mod symbols;
@@ -34,27 +33,6 @@ pub fn symbols(input: TokenStream) -> TokenStream {
     symbols::symbols(input.into()).into()
 }
 
-/// Creates a struct type `S` that can be used as an index with
-/// `IndexVec` and so on.
-///
-/// There are two ways of interacting with these indices:
-///
-/// - The `From` impls are the preferred way. So you can do
-///   `S::from(v)` with a `usize` or `u32`. And you can convert back
-///   to an integer with `u32::from(s)`.
-///
-/// - Alternatively, you can use the methods `S::new(v)` and `s.index()`
-///   to create/return a value.
-///
-/// Internally, the index uses a u32, so the index must not exceed
-/// `u32::MAX`. You can also customize things like the `Debug` impl,
-/// what traits are derived, and so forth via the macro.
-#[proc_macro]
-#[allow_internal_unstable(step_trait, rustc_attrs, trusted_step, spec_option_partial_eq)]
-pub fn newtype_index(input: TokenStream) -> TokenStream {
-    newtype::newtype(input)
-}
-
 decl_derive!([HashStable, attributes(stable_hasher)] => hash_stable::hash_stable_derive);
 decl_derive!(
     [HashStable_Generic, attributes(stable_hasher)] =>

compiler/rustc_mir_transform/src/gvn.rs

@@ -56,8 +56,8 @@
 use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
 use rustc_data_structures::graph::dominators::Dominators;
 use rustc_index::bit_set::BitSet;
+use rustc_index::newtype_index;
 use rustc_index::IndexVec;
-use rustc_macros::newtype_index;
 use rustc_middle::mir::visit::*;
 use rustc_middle::mir::*;
 use rustc_middle::ty::{self, Ty, TyCtxt};

compiler/rustc_type_ir/Cargo.toml

@@ -7,8 +7,19 @@ edition = "2021"
 
 [dependencies]
 bitflags = "1.2.1"
-rustc_index = { path = "../rustc_index" }
-rustc_serialize = { path = "../rustc_serialize" }
-rustc_data_structures = { path = "../rustc_data_structures" }
-rustc_macros = { path = "../rustc_macros" }
-smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
+rustc_index = { path = "../rustc_index", default-features = false }
+rustc_serialize = { path = "../rustc_serialize", optional = true }
+rustc_data_structures = { path = "../rustc_data_structures", optional = true }
+rustc_macros = { path = "../rustc_macros", optional = true }
+smallvec = { version = "1.8.1" }
+
+[features]
+default = ["nightly"]
+nightly = [
+    "smallvec/may_dangle",
+    "smallvec/union",
+    "rustc_index/nightly",
+    "rustc_serialize",
+    "rustc_data_structures",
+    "rustc_macros",
+]

compiler/rustc_type_ir/src/const_kind.rs

@@ -1,13 +1,14 @@
+#[cfg(feature = "nightly")]
 use rustc_data_structures::stable_hasher::HashStable;
+#[cfg(feature = "nightly")]
 use rustc_serialize::{Decodable, Decoder, Encodable};
 use std::cmp::Ordering;
 use std::fmt;
 use std::hash;
 
-use crate::{
-    DebruijnIndex, DebugWithInfcx, HashStableContext, InferCtxtLike, Interner, OptWithInfcx,
-    TyDecoder, TyEncoder,
-};
+use crate::{DebruijnIndex, DebugWithInfcx, InferCtxtLike, Interner, OptWithInfcx};
+#[cfg(feature = "nightly")]
+use crate::{HashStableContext, TyDecoder, TyEncoder};
 
 use self::ConstKind::*;
 
@@ -75,6 +76,7 @@ impl<I: Interner> hash::Hash for ConstKind<I> {
     }
 }
 
+#[cfg(feature = "nightly")]
 impl<CTX: HashStableContext, I: Interner> HashStable<CTX> for ConstKind<I>
 where
     I::ParamConst: HashStable<CTX>,
@@ -108,6 +110,7 @@ where
     }
 }
 
+#[cfg(feature = "nightly")]
 impl<I: Interner, D: TyDecoder<I = I>> Decodable<D> for ConstKind<I>
 where
     I::ParamConst: Decodable<D>,
@@ -140,6 +143,7 @@ where
     }
 }
 
+#[cfg(feature = "nightly")]
 impl<I: Interner, E: TyEncoder<I = I>> Encodable<E> for ConstKind<I>
 where
     I::ParamConst: Encodable<E>,

compiler/rustc_type_ir/src/fold.rs

@@ -45,12 +45,18 @@
 //! - u.fold_with(folder)
 //! ```
 
-use rustc_data_structures::sync::Lrc;
 use rustc_index::{Idx, IndexVec};
 use std::mem;
 
+use crate::Lrc;
 use crate::{visit::TypeVisitable, Interner};
 
+#[cfg(feature = "nightly")]
+type Never = !;
+
+#[cfg(not(feature = "nightly"))]
+type Never = std::convert::Infallible;
+
 /// This trait is implemented for every type that can be folded,
 /// providing the skeleton of the traversal.
 ///
@@ -79,7 +85,10 @@ pub trait TypeFoldable<I: Interner>: TypeVisitable<I> {
     /// folders. Do not override this method, to ensure coherence with
     /// `try_fold_with`.
     fn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self {
-        self.try_fold_with(folder).into_ok()
+        match self.try_fold_with(folder) {
+            Ok(t) => t,
+            Err(e) => match e {},
+        }
     }
 }
 
@@ -100,7 +109,10 @@ pub trait TypeSuperFoldable<I: Interner>: TypeFoldable<I> {
     /// infallible folders. Do not override this method, to ensure coherence
     /// with `try_super_fold_with`.
     fn super_fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self {
-        self.try_super_fold_with(folder).into_ok()
+        match self.try_super_fold_with(folder) {
+            Ok(t) => t,
+            Err(e) => match e {},
+        }
     }
 }
 
@@ -113,7 +125,7 @@ pub trait TypeSuperFoldable<I: Interner>: TypeFoldable<I> {
 /// A blanket implementation of [`FallibleTypeFolder`] will defer to
 /// the infallible methods of this trait to ensure that the two APIs
 /// are coherent.
-pub trait TypeFolder<I: Interner>: FallibleTypeFolder<I, Error = !> {
+pub trait TypeFolder<I: Interner>: FallibleTypeFolder<I, Error = Never> {
     fn interner(&self) -> I;
 
     fn fold_binder<T>(&mut self, t: I::Binder<T>) -> I::Binder<T>
@@ -208,39 +220,39 @@ impl<I: Interner, F> FallibleTypeFolder<I> for F
 where
     F: TypeFolder<I>,
 {
-    type Error = !;
+    type Error = Never;
 
     fn interner(&self) -> I {
         TypeFolder::interner(self)
     }
 
-    fn try_fold_binder<T>(&mut self, t: I::Binder<T>) -> Result<I::Binder<T>, !>
+    fn try_fold_binder<T>(&mut self, t: I::Binder<T>) -> Result<I::Binder<T>, Never>
     where
         T: TypeFoldable<I>,
         I::Binder<T>: TypeSuperFoldable<I>,
     {
         Ok(self.fold_binder(t))
     }
 
-    fn try_fold_ty(&mut self, t: I::Ty) -> Result<I::Ty, !>
+    fn try_fold_ty(&mut self, t: I::Ty) -> Result<I::Ty, Never>
     where
         I::Ty: TypeSuperFoldable<I>,
     {
         Ok(self.fold_ty(t))
     }
 
-    fn try_fold_region(&mut self, r: I::Region) -> Result<I::Region, !> {
+    fn try_fold_region(&mut self, r: I::Region) -> Result<I::Region, Never> {
         Ok(self.fold_region(r))
     }
 
-    fn try_fold_const(&mut self, c: I::Const) -> Result<I::Const, !>
+    fn try_fold_const(&mut self, c: I::Const) -> Result<I::Const, Never>
     where
         I::Const: TypeSuperFoldable<I>,
     {
         Ok(self.fold_const(c))
     }
 
-    fn try_fold_predicate(&mut self, p: I::Predicate) -> Result<I::Predicate, !>
+    fn try_fold_predicate(&mut self, p: I::Predicate) -> Result<I::Predicate, Never>
     where
         I::Predicate: TypeSuperFoldable<I>,
     {
@@ -311,7 +323,7 @@ impl<I: Interner, T: TypeFoldable<I>> TypeFoldable<I> for Lrc<T> {
             // Call to `Lrc::make_mut` above guarantees that `unique` is the
             // sole reference to the contained value, so we can avoid doing
             // a checked `get_mut` here.
-            let slot = Lrc::get_mut_unchecked(&mut unique);
+            let slot = Lrc::get_mut(&mut unique).unwrap_unchecked();
 
             // Semantically move the contained type out from `unique`, fold
             // it, then move the folded value back into `unique`. Should