Auto merge of #62659 - Centril:rollup-90oz643, r=Centril

Rollup of 5 pull requests

Successful merges:

 - #62577 (Add an AtomicCell abstraction)
 - #62585 (Make struct_tail normalize when possible)
 - #62604 (Handle errors during error recovery gracefully)
 - #62636 (rustbuild: Improve assert about building tools once)
 - #62651 (Make some rustc macros more hygienic)

Failed merges:

r? @ghost

Author: bors

Diff for: Cargo.lock

@@ -3018,6 +3018,7 @@ name = "rustc_data_structures"
 version = "0.0.0"
 dependencies = [
  "cfg-if 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-utils 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "ena 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "graphviz 0.0.0",
  "indexmap 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",

Diff for: src/bootstrap/tool.rs

@@ -109,36 +109,63 @@ impl Step for ToolBuild {
                     continue
                 }
 
-                // Don't worry about libs that turn out to be host dependencies
-                // or build scripts, we only care about target dependencies that
-                // are in `deps`.
-                if let Some(maybe_target) = val.1
-                    .parent()                   // chop off file name
-                    .and_then(|p| p.parent())   // chop off `deps`
-                    .and_then(|p| p.parent())   // chop off `release`
-                    .and_then(|p| p.file_name())
-                    .and_then(|p| p.to_str())
-                {
-                    if maybe_target != &*target {
-                        continue
+                // Don't worry about compiles that turn out to be host
+                // dependencies or build scripts. To skip these we look for
+                // anything that goes in `.../release/deps` but *doesn't* go in
+                // `$target/release/deps`. This ensure that outputs in
+                // `$target/release` are still considered candidates for
+                // deduplication.
+                if let Some(parent) = val.1.parent() {
+                    if parent.ends_with("release/deps") {
+                        let maybe_target = parent
+                            .parent()
+                            .and_then(|p| p.parent())
+                            .and_then(|p| p.file_name())
+                            .and_then(|p| p.to_str())
+                            .unwrap();
+                        if maybe_target != &*target {
+                            continue;
+                        }
                     }
                 }
 
+                // Record that we've built an artifact for `id`, and if one was
+                // already listed then we need to see if we reused the same
+                // artifact or produced a duplicate.
                 let mut artifacts = builder.tool_artifacts.borrow_mut();
                 let prev_artifacts = artifacts
                     .entry(target)
                     .or_default();
-                if let Some(prev) = prev_artifacts.get(&*id) {
-                    if prev.1 != val.1 {
-                        duplicates.push((
-                            id.to_string(),
-                            val,
-                            prev.clone(),
-                        ));
+                let prev = match prev_artifacts.get(&*id) {
+                    Some(prev) => prev,
+                    None => {
+                        prev_artifacts.insert(id.to_string(), val);
+                        continue;
                     }
-                    return
+                };
+                if prev.1 == val.1 {
+                    return; // same path, same artifact
                 }
-                prev_artifacts.insert(id.to_string(), val);
+
+                // If the paths are different and one of them *isn't* inside of
+                // `release/deps`, then it means it's probably in
+                // `$target/release`, or it's some final artifact like
+                // `libcargo.rlib`. In these situations Cargo probably just
+                // copied it up from `$target/release/deps/libcargo-xxxx.rlib`,
+                // so if the features are equal we can just skip it.
+                let prev_no_hash = prev.1.parent().unwrap().ends_with("release/deps");
+                let val_no_hash = val.1.parent().unwrap().ends_with("release/deps");
+                if prev.2 == val.2 || !prev_no_hash || !val_no_hash {
+                    return;
+                }
+
+                // ... and otherwise this looks like we duplicated some sort of
+                // compilation, so record it to generate an error later.
+                duplicates.push((
+                    id.to_string(),
+                    val,
+                    prev.clone(),
+                ));
             }
         });
 

Diff for: src/librustc/lib.rs

@@ -49,15 +49,13 @@
 #![feature(optin_builtin_traits)]
 #![feature(range_is_empty)]
 #![feature(rustc_diagnostic_macros)]
-#![feature(rustc_attrs)]
 #![feature(slice_patterns)]
 #![feature(specialization)]
 #![feature(unboxed_closures)]
 #![feature(thread_local)]
 #![feature(trace_macros)]
 #![feature(trusted_len)]
 #![feature(vec_remove_item)]
-#![feature(step_trait)]
 #![feature(stmt_expr_attributes)]
 #![feature(integer_atomics)]
 #![feature(test)]

Diff for: src/librustc/ty/layout.rs

@@ -543,7 +543,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
                     return Ok(tcx.intern_layout(LayoutDetails::scalar(self, data_ptr)));
                 }
 
-                let unsized_part = tcx.struct_tail(pointee);
+                let unsized_part = tcx.struct_tail_erasing_lifetimes(pointee, param_env);
                 let metadata = match unsized_part.sty {
                     ty::Foreign(..) => {
                         return Ok(tcx.intern_layout(LayoutDetails::scalar(self, data_ptr)));
@@ -1664,7 +1664,7 @@ impl<'tcx> SizeSkeleton<'tcx> {
             ty::Ref(_, pointee, _) |
             ty::RawPtr(ty::TypeAndMut { ty: pointee, .. }) => {
                 let non_zero = !ty.is_unsafe_ptr();
-                let tail = tcx.struct_tail(pointee);
+                let tail = tcx.struct_tail_erasing_lifetimes(pointee, param_env);
                 match tail.sty {
                     ty::Param(_) | ty::Projection(_) => {
                         debug_assert!(tail.has_param_types() || tail.has_self_ty());
@@ -2015,7 +2015,7 @@ where
                     }));
                 }
 
-                match tcx.struct_tail(pointee).sty {
+                match tcx.struct_tail_erasing_lifetimes(pointee, cx.param_env()).sty {
                     ty::Slice(_) |
                     ty::Str => tcx.types.usize,
                     ty::Dynamic(_, _) => {

Diff for: src/librustc/ty/util.rs

@@ -257,10 +257,46 @@ impl<'tcx> TyCtxt<'tcx> {
         false
     }
 
-    /// Returns the deeply last field of nested structures, or the same type,
-    /// if not a structure at all. Corresponds to the only possible unsized
-    /// field, and its type can be used to determine unsizing strategy.
-    pub fn struct_tail(self, mut ty: Ty<'tcx>) -> Ty<'tcx> {
+    /// Attempts to returns the deeply last field of nested structures, but
+    /// does not apply any normalization in its search. Returns the same type
+    /// if input `ty` is not a structure at all.
+    pub fn struct_tail_without_normalization(self, ty: Ty<'tcx>) -> Ty<'tcx>
+    {
+        let tcx = self;
+        tcx.struct_tail_with_normalize(ty, |ty| ty)
+    }
+
+    /// Returns the deeply last field of nested structures, or the same type if
+    /// not a structure at all. Corresponds to the only possible unsized field,
+    /// and its type can be used to determine unsizing strategy.
+    ///
+    /// Should only be called if `ty` has no inference variables and does not
+    /// need its lifetimes preserved (e.g. as part of codegen); otherwise
+    /// normalization attempt may cause compiler bugs.
+    pub fn struct_tail_erasing_lifetimes(self,
+                                         ty: Ty<'tcx>,
+                                         param_env: ty::ParamEnv<'tcx>)
+                                         -> Ty<'tcx>
+    {
+        let tcx = self;
+        tcx.struct_tail_with_normalize(ty, |ty| tcx.normalize_erasing_regions(param_env, ty))
+    }
+
+    /// Returns the deeply last field of nested structures, or the same type if
+    /// not a structure at all. Corresponds to the only possible unsized field,
+    /// and its type can be used to determine unsizing strategy.
+    ///
+    /// This is parameterized over the normalization strategy (i.e. how to
+    /// handle `<T as Trait>::Assoc` and `impl Trait`); pass the identity
+    /// function to indicate no normalization should take place.
+    ///
+    /// See also `struct_tail_erasing_lifetimes`, which is suitable for use
+    /// during codegen.
+    pub fn struct_tail_with_normalize(self,
+                                      mut ty: Ty<'tcx>,
+                                      normalize: impl Fn(Ty<'tcx>) -> Ty<'tcx>)
+                                      -> Ty<'tcx>
+    {
         loop {
             match ty.sty {
                 ty::Adt(def, substs) => {
@@ -281,6 +317,15 @@ impl<'tcx> TyCtxt<'tcx> {
                     }
                 }
 
+                ty::Projection(_) | ty::Opaque(..) => {
+                    let normalized = normalize(ty);
+                    if ty == normalized {
+                        return ty;
+                    } else {
+                        ty = normalized;
+                    }
+                }
+
                 _ => {
                     break;
                 }
@@ -294,10 +339,35 @@ impl<'tcx> TyCtxt<'tcx> {
     /// structure definitions.
     /// For `(Foo<Foo<T>>, Foo<dyn Trait>)`, the result will be `(Foo<T>, Trait)`,
     /// whereas struct_tail produces `T`, and `Trait`, respectively.
-    pub fn struct_lockstep_tails(self,
-                                 source: Ty<'tcx>,
-                                 target: Ty<'tcx>)
-                                 -> (Ty<'tcx>, Ty<'tcx>) {
+    ///
+    /// Should only be called if the types have no inference variables and do
+    /// not need their lifetimes preserved (e.g. as part of codegen); otherwise
+    /// normalization attempt may cause compiler bugs.
+    pub fn struct_lockstep_tails_erasing_lifetimes(self,
+                                                   source: Ty<'tcx>,
+                                                   target: Ty<'tcx>,
+                                                   param_env: ty::ParamEnv<'tcx>)
+                                                   -> (Ty<'tcx>, Ty<'tcx>)
+    {
+        let tcx = self;
+        tcx.struct_lockstep_tails_with_normalize(
+            source, target, |ty| tcx.normalize_erasing_regions(param_env, ty))
+    }
+
+    /// Same as applying struct_tail on `source` and `target`, but only
+    /// keeps going as long as the two types are instances of the same
+    /// structure definitions.
+    /// For `(Foo<Foo<T>>, Foo<dyn Trait>)`, the result will be `(Foo<T>, Trait)`,
+    /// whereas struct_tail produces `T`, and `Trait`, respectively.
+    ///
+    /// See also `struct_lockstep_tails_erasing_lifetimes`, which is suitable for use
+    /// during codegen.
+    pub fn struct_lockstep_tails_with_normalize(self,
+                                                source: Ty<'tcx>,
+                                                target: Ty<'tcx>,
+                                                normalize: impl Fn(Ty<'tcx>) -> Ty<'tcx>)
+                                                -> (Ty<'tcx>, Ty<'tcx>)
+    {
         let (mut a, mut b) = (source, target);
         loop {
             match (&a.sty, &b.sty) {
@@ -319,6 +389,22 @@ impl<'tcx> TyCtxt<'tcx> {
                         break;
                     }
                 },
+                (ty::Projection(_), _) | (ty::Opaque(..), _) |
+                (_, ty::Projection(_)) | (_, ty::Opaque(..)) => {
+                    // If either side is a projection, attempt to
+                    // progress via normalization. (Should be safe to
+                    // apply to both sides as normalization is
+                    // idempotent.)
+                    let a_norm = normalize(a);
+                    let b_norm = normalize(b);
+                    if a == a_norm && b == b_norm {
+                        break;
+                    } else {
+                        a = a_norm;
+                        b = b_norm;
+                    }
+                }
+
                 _ => break,
             }
         }

Diff for: src/librustc_codegen_ssa/base.rs

@@ -128,7 +128,8 @@ pub fn unsized_info<'tcx, Cx: CodegenMethods<'tcx>>(
     target: Ty<'tcx>,
     old_info: Option<Cx::Value>,
 ) -> Cx::Value {
-    let (source, target) = cx.tcx().struct_lockstep_tails(source, target);
+    let (source, target) =
+        cx.tcx().struct_lockstep_tails_erasing_lifetimes(source, target, cx.param_env());
     match (&source.sty, &target.sty) {
         (&ty::Array(_, len), &ty::Slice(_)) => {
             cx.const_usize(len.unwrap_usize(cx.tcx()))

Diff for: src/librustc_codegen_ssa/traits/type_.rs

@@ -77,11 +77,12 @@ pub trait DerivedTypeMethods<'tcx>: BaseTypeMethods<'tcx> + MiscMethods<'tcx> {
     }
 
     fn type_has_metadata(&self, ty: Ty<'tcx>) -> bool {
-        if ty.is_sized(self.tcx().at(DUMMY_SP), ty::ParamEnv::reveal_all()) {
+        let param_env = ty::ParamEnv::reveal_all();
+        if ty.is_sized(self.tcx().at(DUMMY_SP), param_env) {
             return false;
         }
 
-        let tail = self.tcx().struct_tail(ty);
+        let tail = self.tcx().struct_tail_erasing_lifetimes(ty, param_env);
         match tail.sty {
             ty::Foreign(..) => false,
             ty::Str | ty::Slice(..) | ty::Dynamic(..) => true,

Diff for: src/librustc_data_structures/Cargo.toml

@@ -18,6 +18,7 @@ lazy_static = "1"
 serialize = { path = "../libserialize" }
 graphviz = { path = "../libgraphviz" }
 cfg-if = "0.1.2"
+crossbeam-utils = { version = "0.6.5", features = ["nightly"] }
 stable_deref_trait = "1.0.0"
 rayon = { version = "0.2.0", package = "rustc-rayon" }
 rayon-core = { version = "0.2.0", package = "rustc-rayon-core" }