Auto merge of rust-lang#77490 - Mark-Simulacrum:beta-backports, r=Mark-Simulacrum

[beta] backports

This backports a number of PRs to beta, not all of which have been approved (yet).

 * Switch to environment files to change the environment on GHA rust-lang#77418
 * cache types during normalization rust-lang#76928
 * Fixing memory exhaustion when formatting short code suggestion rust-lang#76598
 * Issue 72408 nested closures exponential rust-lang#72412

r? `@Mark-Simulacrum`

Author: bors

Cargo.lock

@@ -3424,6 +3424,7 @@ dependencies = [
 name = "rustc_data_structures"
 version = "0.0.0"
 dependencies = [
+ "arrayvec",
  "bitflags",
  "cfg-if",
  "crossbeam-utils 0.7.2",
@@ -3599,6 +3600,7 @@ dependencies = [
 name = "rustc_infer"
 version = "0.0.0"
 dependencies = [
+ "arrayvec",
  "rustc_ast",
  "rustc_data_structures",
  "rustc_errors",
@@ -3738,6 +3740,7 @@ dependencies = [
 name = "rustc_middle"
 version = "0.0.0"
 dependencies = [
+ "arrayvec",
  "bitflags",
  "byteorder",
  "chalk-ir",

src/ci/shared.sh

@@ -104,7 +104,7 @@ function ciCommandAddPath {
     if isAzurePipelines; then
         echo "##vso[task.prependpath]${path}"
     elif isGitHubActions; then
-        echo "::add-path::${path}"
+        echo "${path}" >> "${GITHUB_PATH}"
     else
         echo "ciCommandAddPath only works inside CI!"
         exit 1
@@ -122,7 +122,7 @@ function ciCommandSetEnv {
     if isAzurePipelines; then
         echo "##vso[task.setvariable variable=${name}]${value}"
     elif isGitHubActions; then
-        echo "::set-env name=${name}::${value}"
+        echo "${name}=${value}" >> "${GITHUB_ENV}"
     else
         echo "ciCommandSetEnv only works inside CI!"
         exit 1

src/librustc_data_structures/Cargo.toml

@@ -10,6 +10,7 @@ path = "lib.rs"
 doctest = false
 
 [dependencies]
+arrayvec = { version = "0.5.1", default-features = false }
 ena = "0.14"
 indexmap = "1.5.1"
 tracing = "0.1"

src/librustc_data_structures/lib.rs

@@ -85,24 +85,26 @@ pub mod sorted_map;
 pub mod stable_set;
 #[macro_use]
 pub mod stable_hasher;
+mod atomic_ref;
+pub mod fingerprint;
+pub mod profiling;
 pub mod sharded;
 pub mod stack;
 pub mod sync;
 pub mod thin_vec;
 pub mod tiny_list;
 pub mod transitive_relation;
-pub use ena::undo_log;
-pub use ena::unify;
-mod atomic_ref;
-pub mod fingerprint;
-pub mod profiling;
 pub mod vec_linked_list;
 pub mod work_queue;
 pub use atomic_ref::AtomicRef;
 pub mod frozen;
+pub mod mini_map;
 pub mod tagged_ptr;
 pub mod temp_dir;
 
+pub use ena::undo_log;
+pub use ena::unify;
+
 pub struct OnDrop<F: Fn()>(pub F);
 
 impl<F: Fn()> OnDrop<F> {

src/librustc_data_structures/mini_map.rs

@@ -0,0 +1,61 @@
+use crate::fx::FxHashMap;
+use arrayvec::ArrayVec;
+
+use std::hash::Hash;
+
+/// Small-storage-optimized implementation of a map
+/// made specifically for caching results.
+///
+/// Stores elements in a small array up to a certain length
+/// and switches to `HashMap` when that length is exceeded.
+pub enum MiniMap<K, V> {
+    Array(ArrayVec<[(K, V); 8]>),
+    Map(FxHashMap<K, V>),
+}
+
+impl<K: Eq + Hash, V> MiniMap<K, V> {
+    /// Creates an empty `MiniMap`.
+    pub fn new() -> Self {
+        MiniMap::Array(ArrayVec::new())
+    }
+
+    /// Inserts or updates value in the map.
+    pub fn insert(&mut self, key: K, value: V) {
+        match self {
+            MiniMap::Array(array) => {
+                for pair in array.iter_mut() {
+                    if pair.0 == key {
+                        pair.1 = value;
+                        return;
+                    }
+                }
+                if let Err(error) = array.try_push((key, value)) {
+                    let mut map: FxHashMap<K, V> = array.drain(..).collect();
+                    let (key, value) = error.element();
+                    map.insert(key, value);
+                    *self = MiniMap::Map(map);
+                }
+            }
+            MiniMap::Map(map) => {
+                map.insert(key, value);
+            }
+        }
+    }
+
+    /// Return value by key if any.
+    pub fn get(&self, key: &K) -> Option<&V> {
+        match self {
+            MiniMap::Array(array) => {
+                for pair in array {
+                    if pair.0 == *key {
+                        return Some(&pair.1);
+                    }
+                }
+                return None;
+            }
+            MiniMap::Map(map) => {
+                return map.get(key);
+            }
+        }
+    }
+}

src/librustc_errors/emitter.rs

@@ -959,15 +959,15 @@ impl EmitterWriter {
                         '_',
                         line_offset + pos,
                         width_offset + depth,
-                        code_offset + annotation.start_col - left,
+                        (code_offset + annotation.start_col).saturating_sub(left),
                         style,
                     );
                 }
                 _ if self.teach => {
                     buffer.set_style_range(
                         line_offset,
-                        code_offset + annotation.start_col - left,
-                        code_offset + annotation.end_col - left,
+                        (code_offset + annotation.start_col).saturating_sub(left),
+                        (code_offset + annotation.end_col).saturating_sub(left),
                         style,
                         annotation.is_primary,
                     );

src/librustc_index/Cargo.toml

@@ -10,6 +10,6 @@ path = "lib.rs"
 doctest = false
 
 [dependencies]
-arrayvec = "0.5.1"
+arrayvec = { version = "0.5.1", default-features = false }
 rustc_serialize = { path = "../librustc_serialize" }
 rustc_macros = { path = "../librustc_macros" }

src/librustc_infer/Cargo.toml

@@ -23,4 +23,5 @@ rustc_serialize = { path = "../librustc_serialize" }
 rustc_span = { path = "../librustc_span" }
 rustc_target = { path = "../librustc_target" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
+arrayvec = { version = "0.5.1", default-features = false }
 rustc_ast = { path = "../librustc_ast" }

src/librustc_infer/infer/combine.rs

@@ -35,6 +35,7 @@ use super::{InferCtxt, MiscVariable, TypeTrace};
 use crate::traits::{Obligation, PredicateObligations};
 
 use rustc_ast as ast;
+use rustc_data_structures::mini_map::MiniMap;
 use rustc_hir::def_id::DefId;
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::error::TypeError;
@@ -379,6 +380,7 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
             needs_wf: false,
             root_ty: ty,
             param_env: self.param_env,
+            cache: MiniMap::new(),
         };
 
         let ty = match generalize.relate(ty, ty) {
@@ -438,6 +440,8 @@ struct Generalizer<'cx, 'tcx> {
     root_ty: Ty<'tcx>,
 
     param_env: ty::ParamEnv<'tcx>,
+
+    cache: MiniMap<Ty<'tcx>, RelateResult<'tcx, Ty<'tcx>>>,
 }
 
 /// Result from a generalization operation. This includes
@@ -535,13 +539,16 @@ impl TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
     fn tys(&mut self, t: Ty<'tcx>, t2: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
         assert_eq!(t, t2); // we are abusing TypeRelation here; both LHS and RHS ought to be ==
 
+        if let Some(result) = self.cache.get(&t) {
+            return result.clone();
+        }
         debug!("generalize: t={:?}", t);
 
         // Check to see whether the type we are generalizing references
         // any other type variable related to `vid` via
         // subtyping. This is basically our "occurs check", preventing
         // us from creating infinitely sized types.
-        match t.kind {
+        let result = match t.kind {
             ty::Infer(ty::TyVar(vid)) => {
                 let vid = self.infcx.inner.borrow_mut().type_variables().root_var(vid);
                 let sub_vid = self.infcx.inner.borrow_mut().type_variables().sub_root_var(vid);
@@ -598,7 +605,10 @@ impl TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
                 Ok(t)
             }
             _ => relate::super_relate_tys(self, t, t),
-        }
+        };
+
+        self.cache.insert(t, result.clone());
+        return result;
     }
 
     fn regions(

src/librustc_infer/infer/outlives/verify.rs

@@ -3,6 +3,7 @@ use crate::infer::{GenericKind, VerifyBound};
 use rustc_data_structures::captures::Captures;
 use rustc_hir::def_id::DefId;
 use rustc_middle::ty::subst::{GenericArg, GenericArgKind, Subst};
+use rustc_middle::ty::walk::MiniSet;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 
 /// The `TypeOutlives` struct has the job of "lowering" a `T: 'a`
@@ -31,16 +32,23 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> {
     /// Returns a "verify bound" that encodes what we know about
     /// `generic` and the regions it outlives.
     pub fn generic_bound(&self, generic: GenericKind<'tcx>) -> VerifyBound<'tcx> {
+        let mut visited = MiniSet::new();
         match generic {
             GenericKind::Param(param_ty) => self.param_bound(param_ty),
-            GenericKind::Projection(projection_ty) => self.projection_bound(projection_ty),
+            GenericKind::Projection(projection_ty) => {
+                self.projection_bound(projection_ty, &mut visited)
+            }
         }
     }
 
-    fn type_bound(&self, ty: Ty<'tcx>) -> VerifyBound<'tcx> {
+    fn type_bound(
+        &self,
+        ty: Ty<'tcx>,
+        visited: &mut MiniSet<GenericArg<'tcx>>,
+    ) -> VerifyBound<'tcx> {
         match ty.kind {
             ty::Param(p) => self.param_bound(p),
-            ty::Projection(data) => self.projection_bound(data),
+            ty::Projection(data) => self.projection_bound(data, visited),
             ty::FnDef(_, substs) => {
                 // HACK(eddyb) ignore lifetimes found shallowly in `substs`.
                 // This is inconsistent with `ty::Adt` (including all substs),
@@ -50,9 +58,9 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> {
                 let mut bounds = substs
                     .iter()
                     .filter_map(|child| match child.unpack() {
-                        GenericArgKind::Type(ty) => Some(self.type_bound(ty)),
+                        GenericArgKind::Type(ty) => Some(self.type_bound(ty, visited)),
                         GenericArgKind::Lifetime(_) => None,
-                        GenericArgKind::Const(_) => Some(self.recursive_bound(child)),
+                        GenericArgKind::Const(_) => Some(self.recursive_bound(child, visited)),
                     })
                     .filter(|bound| {
                         // Remove bounds that must hold, since they are not interesting.
@@ -66,7 +74,7 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> {
                     ),
                 }
             }
-            _ => self.recursive_bound(ty.into()),
+            _ => self.recursive_bound(ty.into(), visited),
         }
     }
 
@@ -137,7 +145,11 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> {
         self.declared_projection_bounds_from_trait(projection_ty)
     }
 
-    pub fn projection_bound(&self, projection_ty: ty::ProjectionTy<'tcx>) -> VerifyBound<'tcx> {
+    pub fn projection_bound(
+        &self,
+        projection_ty: ty::ProjectionTy<'tcx>,
+        visited: &mut MiniSet<GenericArg<'tcx>>,
+    ) -> VerifyBound<'tcx> {
         debug!("projection_bound(projection_ty={:?})", projection_ty);
 
         let projection_ty_as_ty =
@@ -166,21 +178,25 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> {
 
         // see the extensive comment in projection_must_outlive
         let ty = self.tcx.mk_projection(projection_ty.item_def_id, projection_ty.substs);
-        let recursive_bound = self.recursive_bound(ty.into());
+        let recursive_bound = self.recursive_bound(ty.into(), visited);
 
         VerifyBound::AnyBound(env_bounds.chain(trait_bounds).collect()).or(recursive_bound)
     }
 
-    fn recursive_bound(&self, parent: GenericArg<'tcx>) -> VerifyBound<'tcx> {
+    fn recursive_bound(
+        &self,
+        parent: GenericArg<'tcx>,
+        visited: &mut MiniSet<GenericArg<'tcx>>,
+    ) -> VerifyBound<'tcx> {
         let mut bounds = parent
-            .walk_shallow()
+            .walk_shallow(visited)
             .filter_map(|child| match child.unpack() {
-                GenericArgKind::Type(ty) => Some(self.type_bound(ty)),
+                GenericArgKind::Type(ty) => Some(self.type_bound(ty, visited)),
                 GenericArgKind::Lifetime(lt) => {
                     // Ignore late-bound regions.
                     if !lt.is_late_bound() { Some(VerifyBound::OutlivedBy(lt)) } else { None }
                 }
-                GenericArgKind::Const(_) => Some(self.recursive_bound(child)),
+                GenericArgKind::Const(_) => Some(self.recursive_bound(child, visited)),
             })
             .filter(|bound| {
                 // Remove bounds that must hold, since they are not interesting.

src/librustc_middle/Cargo.toml

@@ -31,5 +31,6 @@ rustc_span = { path = "../librustc_span" }
 byteorder = { version = "1.3" }
 chalk-ir = "0.14.0"
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
+arrayvec = { version = "0.5.1", default-features = false }
 measureme = "0.7.1"
 rustc_session = { path = "../librustc_session" }