Auto merge of #57305 - pietroalbini:beta-rollup, r=pietroalbini

[beta] Rollup backports

Cherry-picked:

* #57053: Fix alignment for array indexing
* #57181: resolve: Fix another ICE in import validation
* #57185: resolve: Fix one more ICE in import validation
* #57282: Wf-check the output type of a function in MIR-typeck
* #55318: Ensure that Rustdoc discovers all necessary auto trait bounds
* #56838: Call poly_project_and_unify_type on types that contain inference types

Rolled up:

* #57300: [beta] Update RLS to include 100% CPU on hover bugfix
* #57301: beta: bootstrap from latest stable (1.31.1)
* #57292: [BETA] Update cargo

r? @ghost

Author: bors

src/librustc/traits/auto_trait.rs

@@ -334,7 +334,12 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
                 continue;
             }
 
-            let result = select.select(&Obligation::new(dummy_cause.clone(), new_env, pred));
+            // Call infcx.resolve_type_vars_if_possible to see if we can
+            // get rid of any inference variables.
+            let obligation = infcx.resolve_type_vars_if_possible(
+                &Obligation::new(dummy_cause.clone(), new_env, pred)
+            );
+            let result = select.select(&obligation);
 
             match &result {
                 &Ok(Some(ref vtable)) => {
@@ -369,7 +374,7 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
                 }
                 &Ok(None) => {}
                 &Err(SelectionError::Unimplemented) => {
-                    if self.is_of_param(pred.skip_binder().trait_ref.substs) {
+                    if self.is_param_no_infer(pred.skip_binder().trait_ref.substs) {
                         already_visited.remove(&pred);
                         self.add_user_pred(
                             &mut user_computed_preds,
@@ -631,18 +636,28 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
         finished_map
     }
 
-    pub fn is_of_param(&self, substs: &Substs<'_>) -> bool {
-        if substs.is_noop() {
-            return false;
-        }
+    fn is_param_no_infer(&self, substs: &Substs<'_>) -> bool {
+        return self.is_of_param(substs.type_at(0)) &&
+            !substs.types().any(|t| t.has_infer_types());
+    }
 
-        return match substs.type_at(0).sty {
+    pub fn is_of_param(&self, ty: Ty<'_>) -> bool {
+        return match ty.sty {
             ty::Param(_) => true,
-            ty::Projection(p) => self.is_of_param(p.substs),
+            ty::Projection(p) => self.is_of_param(p.self_ty()),
             _ => false,
         };
     }
 
+    fn is_self_referential_projection(&self, p: ty::PolyProjectionPredicate<'_>) -> bool {
+        match p.ty().skip_binder().sty {
+            ty::Projection(proj) if proj == p.skip_binder().projection_ty => {
+                true
+            },
+            _ => false
+        }
+    }
+
     pub fn evaluate_nested_obligations<
         'b,
         'c,
@@ -661,28 +676,77 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
     ) -> bool {
         let dummy_cause = ObligationCause::misc(DUMMY_SP, ast::DUMMY_NODE_ID);
 
-        for (obligation, predicate) in nested
-            .filter(|o| o.recursion_depth == 1)
+        for (obligation, mut predicate) in nested
             .map(|o| (o.clone(), o.predicate.clone()))
         {
             let is_new_pred =
                 fresh_preds.insert(self.clean_pred(select.infcx(), predicate.clone()));
 
+            // Resolve any inference variables that we can, to help selection succeed
+            predicate = select.infcx().resolve_type_vars_if_possible(&predicate);
+
+            // We only add a predicate as a user-displayable bound if
+            // it involves a generic parameter, and doesn't contain
+            // any inference variables.
+            //
+            // Displaying a bound involving a concrete type (instead of a generic
+            // parameter) would be pointless, since it's always true
+            // (e.g. u8: Copy)
+            // Displaying an inference variable is impossible, since they're
+            // an internal compiler detail without a defined visual representation
+            //
+            // We check this by calling is_of_param on the relevant types
+            // from the various possible predicates
             match &predicate {
                 &ty::Predicate::Trait(ref p) => {
-                    let substs = &p.skip_binder().trait_ref.substs;
+                    if self.is_param_no_infer(p.skip_binder().trait_ref.substs)
+                        && !only_projections
+                        && is_new_pred {
 
-                    if self.is_of_param(substs) && !only_projections && is_new_pred {
                         self.add_user_pred(computed_preds, predicate);
                     }
                     predicates.push_back(p.clone());
                 }
                 &ty::Predicate::Projection(p) => {
-                    // If the projection isn't all type vars, then
-                    // we don't want to add it as a bound
-                    if self.is_of_param(p.skip_binder().projection_ty.substs) && is_new_pred {
-                        self.add_user_pred(computed_preds, predicate);
-                    } else {
+                    debug!("evaluate_nested_obligations: examining projection predicate {:?}",
+                           predicate);
+
+                    // As described above, we only want to display
+                    // bounds which include a generic parameter but don't include
+                    // an inference variable.
+                    // Additionally, we check if we've seen this predicate before,
+                    // to avoid rendering duplicate bounds to the user.
+                    if self.is_param_no_infer(p.skip_binder().projection_ty.substs)
+                        && !p.ty().skip_binder().is_ty_infer()
+                        && is_new_pred {
+                            debug!("evaluate_nested_obligations: adding projection predicate\
+                            to computed_preds: {:?}", predicate);
+
+                            // Under unusual circumstances, we can end up with a self-refeential
+                            // projection predicate. For example:
+                            // <T as MyType>::Value == <T as MyType>::Value
+                            // Not only is displaying this to the user pointless,
+                            // having it in the ParamEnv will cause an issue if we try to call
+                            // poly_project_and_unify_type on the predicate, since this kind of
+                            // predicate will normally never end up in a ParamEnv.
+                            //
+                            // For these reasons, we ignore these weird predicates,
+                            // ensuring that we're able to properly synthesize an auto trait impl
+                            if self.is_self_referential_projection(p) {
+                                debug!("evaluate_nested_obligations: encountered a projection
+                                 predicate equating a type with itself! Skipping");
+
+                            } else {
+                                self.add_user_pred(computed_preds, predicate);
+                            }
+                    }
+
+                    // We can only call poly_project_and_unify_type when our predicate's
+                    // Ty contains an inference variable - otherwise, there won't be anything to
+                    // unify
+                    if p.ty().skip_binder().has_infer_types() {
+                        debug!("Projecting and unifying projection predicate {:?}",
+                               predicate);
                         match poly_project_and_unify_type(select, &obligation.with(p.clone())) {
                             Err(e) => {
                                 debug!(

src/librustc_codegen_ssa/mir/place.rs

@@ -335,11 +335,20 @@ impl<'a, 'tcx: 'a, V: CodegenObject> PlaceRef<'tcx, V> {
         bx: &mut Bx,
         llindex: V
     ) -> Self {
+        // Statically compute the offset if we can, otherwise just use the element size,
+        // as this will yield the lowest alignment.
+        let layout = self.layout.field(bx, 0);
+        let offset = if bx.is_const_integral(llindex) {
+            layout.size.checked_mul(bx.const_to_uint(llindex), bx).unwrap_or(layout.size)
+        } else {
+            layout.size
+        };
+
         PlaceRef {
             llval: bx.inbounds_gep(self.llval, &[bx.cx().const_usize(0), llindex]),
             llextra: None,
-            layout: self.layout.field(bx.cx(), 0),
-            align: self.align
+            layout,
+            align: self.align.restrict_for_offset(offset),
         }
     }
 

src/librustc_codegen_ssa/mir/rvalue.rs

@@ -131,8 +131,9 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 let keep_going = header_bx.icmp(IntPredicate::IntNE, current, end);
                 header_bx.cond_br(keep_going, body_bx.llbb(), next_bx.llbb());
 
+                let align = dest.align.restrict_for_offset(dest.layout.field(bx.cx(), 0).size);
                 cg_elem.val.store(&mut body_bx,
-                    PlaceRef::new_sized(current, cg_elem.layout, dest.align));
+                    PlaceRef::new_sized(current, cg_elem.layout, align));
 
                 let next = body_bx.inbounds_gep(current, &[bx.cx().const_usize(1)]);
                 body_bx.br(header_bx.llbb());

src/librustc_mir/borrow_check/nll/type_check/mod.rs

@@ -1415,7 +1415,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
                 self.check_call_dest(mir, term, &sig, destination, term_location);
 
                 self.prove_predicates(
-                    sig.inputs().iter().map(|ty| ty::Predicate::WellFormed(ty)),
+                    sig.inputs_and_output.iter().map(|ty| ty::Predicate::WellFormed(ty)),
                     term_location.to_locations(),
                     ConstraintCategory::Boring,
                 );

src/librustc_mir/interpret/machine.rs

@@ -86,7 +86,7 @@ pub trait Machine<'a, 'mir, 'tcx>: Sized {
     type MemoryExtra: Default;
 
     /// Extra data stored in every allocation.
-    type AllocExtra: AllocationExtra<Self::PointerTag, Self::MemoryExtra>;
+    type AllocExtra: AllocationExtra<Self::PointerTag, Self::MemoryExtra> + 'static;
 
     /// Memory's allocation map
     type MemoryMap:

src/librustc_resolve/lib.rs

@@ -1022,11 +1022,11 @@ enum ModuleOrUniformRoot<'a> {
     CurrentScope,
 }
 
-impl<'a> PartialEq for ModuleOrUniformRoot<'a> {
-    fn eq(&self, other: &Self) -> bool {
-        match (*self, *other) {
+impl ModuleOrUniformRoot<'_> {
+    fn same_def(lhs: Self, rhs: Self) -> bool {
+        match (lhs, rhs) {
             (ModuleOrUniformRoot::Module(lhs),
-             ModuleOrUniformRoot::Module(rhs)) => ptr::eq(lhs, rhs),
+             ModuleOrUniformRoot::Module(rhs)) => lhs.def() == rhs.def(),
             (ModuleOrUniformRoot::CrateRootAndExternPrelude,
              ModuleOrUniformRoot::CrateRootAndExternPrelude) |
             (ModuleOrUniformRoot::ExternPrelude, ModuleOrUniformRoot::ExternPrelude) |

src/librustc_resolve/resolve_imports.rs

@@ -465,6 +465,10 @@ impl<'a, 'crateloader> Resolver<'a, 'crateloader> {
         self.set_binding_parent_module(binding, module);
         self.update_resolution(module, ident, ns, |this, resolution| {
             if let Some(old_binding) = resolution.binding {
+                if binding.def() == Def::Err {
+                    // Do not override real bindings with `Def::Err`s from error recovery.
+                    return Ok(());
+                }
                 match (old_binding.is_glob_import(), binding.is_glob_import()) {
                     (true, true) => {
                         if binding.def() != old_binding.def() {
@@ -836,7 +840,9 @@ impl<'a, 'b:'a, 'c: 'b> ImportResolver<'a, 'b, 'c> {
             PathResult::Module(module) => {
                 // Consistency checks, analogous to `finalize_current_module_macro_resolutions`.
                 if let Some(initial_module) = directive.imported_module.get() {
-                    if module != initial_module && self.ambiguity_errors.is_empty() {
+                    if !ModuleOrUniformRoot::same_def(module, initial_module)
+                        && self.ambiguity_errors.is_empty()
+                    {
                         span_bug!(directive.span, "inconsistent resolution for an import");
                     }
                 } else {

src/stage0.txt

@@ -12,8 +12,8 @@
 # source tarball for a stable release you'll likely see `1.x.0` for rustc and
 # `0.x.0` for Cargo where they were released on `date`.
 
-date: 2018-12-06
-rustc: 1.31.0
+date: 2018-12-20
+rustc: 1.31.1
 cargo: 0.32.0
 
 # When making a stable release the process currently looks like:

src/test/codegen/issue-56927.rs

@@ -0,0 +1,44 @@
+// compile-flags: -C no-prepopulate-passes
+
+#![crate_type="rlib"]
+use std::usize;
+
+#[repr(align(16))]
+pub struct S {
+    arr: [u32; 4],
+}
+
+// CHECK-LABEL: @test1
+// CHECK: store i32 0, i32* %{{.+}}, align 16
+// CHECK: store i32 1, i32* %{{.+}}, align 4
+// CHECK: store i32 2, i32* %{{.+}}, align 8
+// CHECK: store i32 3, i32* %{{.+}}, align 4
+#[no_mangle]
+pub fn test1(s: &mut S) {
+    s.arr[0] = 0;
+    s.arr[1] = 1;
+    s.arr[2] = 2;
+    s.arr[3] = 3;
+}
+
+// CHECK-LABEL: @test2
+// CHECK: store i32 4, i32* %{{.+}}, align 4
+#[allow(const_err)]
+#[no_mangle]
+pub fn test2(s: &mut S) {
+    s.arr[usize::MAX / 4 + 1] = 4;
+}
+
+// CHECK-LABEL: @test3
+// CHECK: store i32 5, i32* %{{.+}}, align 4
+#[no_mangle]
+pub fn test3(s: &mut S, i: usize) {
+    s.arr[i] = 5;
+}
+
+// CHECK-LABEL: @test4
+// CHECK: store i32 6, i32* %{{.+}}, align 4
+#[no_mangle]
+pub fn test4(s: &mut S) {
+    s.arr = [6; 4];
+}

src/test/codegen/packed.rs

@@ -84,6 +84,42 @@ pub fn call_pkd2(f: fn() -> Array) -> BigPacked2 {
     BigPacked2 { dealign: 0, data: f() }
 }
 
+// CHECK-LABEL: @write_packed_array1
+// CHECK: store i32 0, i32* %{{.+}}, align 1
+// CHECK: store i32 1, i32* %{{.+}}, align 1
+// CHECK: store i32 2, i32* %{{.+}}, align 1
+#[no_mangle]
+pub fn write_packed_array1(p: &mut BigPacked1) {
+    p.data.0[0] = 0;
+    p.data.0[1] = 1;
+    p.data.0[2] = 2;
+}
+
+// CHECK-LABEL: @write_packed_array2
+// CHECK: store i32 0, i32* %{{.+}}, align 2
+// CHECK: store i32 1, i32* %{{.+}}, align 2
+// CHECK: store i32 2, i32* %{{.+}}, align 2
+#[no_mangle]
+pub fn write_packed_array2(p: &mut BigPacked2) {
+    p.data.0[0] = 0;
+    p.data.0[1] = 1;
+    p.data.0[2] = 2;
+}
+
+// CHECK-LABEL: @repeat_packed_array1
+// CHECK: store i32 42, i32* %{{.+}}, align 1
+#[no_mangle]
+pub fn repeat_packed_array1(p: &mut BigPacked1) {
+    p.data.0 = [42; 8];
+}
+
+// CHECK-LABEL: @repeat_packed_array2
+// CHECK: store i32 42, i32* %{{.+}}, align 2
+#[no_mangle]
+pub fn repeat_packed_array2(p: &mut BigPacked2) {
+    p.data.0 = [42; 8];
+}
+
 #[repr(packed)]
 #[derive(Copy, Clone)]
 pub struct Packed1Pair(u8, u32);

src/test/rustdoc/issue-50159.rs

@@ -0,0 +1,31 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+
+pub trait Signal {
+    type Item;
+}
+
+pub trait Signal2 {
+    type Item2;
+}
+
+impl<B, C> Signal2 for B where B: Signal<Item = C> {
+    type Item2 = C;
+}
+
+// @has issue_50159/struct.Switch.html
+// @has - '//code' 'impl<B> Send for Switch<B> where <B as Signal>::Item: Send'
+// @has - '//code' 'impl<B> Sync for Switch<B> where <B as Signal>::Item: Sync'
+// @count - '//*[@id="implementations-list"]/*[@class="impl"]' 0
+// @count - '//*[@id="synthetic-implementations-list"]/*[@class="impl"]' 2
+pub struct Switch<B: Signal> {
+    pub inner: <B as Signal2>::Item2,
+}