Rollup of 4 pull requests

Cargo.lock

@@ -3978,7 +3978,6 @@ name = "rustc_middle"
 version = "0.0.0"
 dependencies = [
  "arena",
- "backtrace",
  "bitflags",
  "byteorder",
  "log",

src/librustc_infer/infer/at.rs

@@ -186,7 +186,6 @@ impl<'a, 'tcx> At<'a, 'tcx> {
 impl<'a, 'tcx> Trace<'a, 'tcx> {
     /// Makes `a <: b` where `a` may or may not be expected (if
     /// `a_is_expected` is true, then `a` is expected).
-    /// Makes `expected <: actual`.
     pub fn sub<T>(self, a: &T, b: &T) -> InferResult<'tcx, ()>
     where
         T: Relate<'tcx>,

src/librustc_middle/Cargo.toml

@@ -30,7 +30,6 @@ rustc_index = { path = "../librustc_index" }
 rustc_serialize = { path = "../libserialize", package = "serialize" }
 rustc_ast = { path = "../librustc_ast" }
 rustc_span = { path = "../librustc_span" }
-backtrace = "0.3.40"
 byteorder = { version = "1.3" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 measureme = "0.7.1"

src/librustc_middle/lib.rs

@@ -23,6 +23,7 @@
 //! This API is completely unstable and subject to change.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![feature(backtrace)]
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]

src/librustc_middle/mir/interpret/error.rs

@@ -6,7 +6,6 @@ use crate::ty::query::TyCtxtAt;
 use crate::ty::tls;
 use crate::ty::{self, layout, Ty};
 
-use backtrace::Backtrace;
 use rustc_data_structures::sync::Lock;
 use rustc_errors::{struct_span_err, DiagnosticBuilder, ErrorReported};
 use rustc_hir as hir;
@@ -15,7 +14,7 @@ use rustc_macros::HashStable;
 use rustc_session::CtfeBacktrace;
 use rustc_span::{def_id::DefId, Pos, Span};
 use rustc_target::abi::{Align, Size};
-use std::{any::Any, fmt, mem};
+use std::{any::Any, backtrace::Backtrace, fmt, mem};
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, HashStable, RustcEncodable, RustcDecodable)]
 pub enum ErrorHandled {
@@ -219,16 +218,15 @@ impl fmt::Display for InterpErrorInfo<'_> {
 }
 
 impl InterpErrorInfo<'_> {
-    pub fn print_backtrace(&mut self) {
-        if let Some(ref mut backtrace) = self.backtrace {
-            print_backtrace(&mut *backtrace);
+    pub fn print_backtrace(&self) {
+        if let Some(backtrace) = self.backtrace.as_ref() {
+            print_backtrace(backtrace);
         }
     }
 }
 
-fn print_backtrace(backtrace: &mut Backtrace) {
-    backtrace.resolve();
-    eprintln!("\n\nAn error occurred in miri:\n{:?}", backtrace);
+fn print_backtrace(backtrace: &Backtrace) {
+    eprintln!("\n\nAn error occurred in miri:\n{}", backtrace);
 }
 
 impl From<ErrorHandled> for InterpErrorInfo<'_> {
@@ -255,11 +253,11 @@ impl<'tcx> From<InterpError<'tcx>> for InterpErrorInfo<'tcx> {
 
         let backtrace = match capture_backtrace {
             CtfeBacktrace::Disabled => None,
-            CtfeBacktrace::Capture => Some(Box::new(Backtrace::new_unresolved())),
+            CtfeBacktrace::Capture => Some(Box::new(Backtrace::force_capture())),
             CtfeBacktrace::Immediate => {
                 // Print it now.
-                let mut backtrace = Backtrace::new_unresolved();
-                print_backtrace(&mut backtrace);
+                let backtrace = Backtrace::force_capture();
+                print_backtrace(&backtrace);
                 None
             }
         };

src/librustc_middle/mir/interpret/pointer.rs

@@ -101,18 +101,14 @@ pub trait PointerArithmetic: HasDataLayout {
 
 impl<T: HasDataLayout> PointerArithmetic for T {}
 
-/// `Pointer` is generic over the type that represents a reference to `Allocation`s,
-/// thus making it possible for the most convenient representation to be used in
-/// each context.
+/// Represents a pointer in the Miri engine.
 ///
-/// Defaults to the index based and loosely coupled `AllocId`.
-///
-/// `Pointer` is also generic over the `Tag` associated with each pointer,
+/// `Pointer` is generic over the `Tag` associated with each pointer,
 /// which is used to do provenance tracking during execution.
 #[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, RustcEncodable, RustcDecodable, Hash)]
 #[derive(HashStable)]
-pub struct Pointer<Tag = (), Id = AllocId> {
-    pub alloc_id: Id,
+pub struct Pointer<Tag = ()> {
+    pub alloc_id: AllocId,
     pub offset: Size,
     pub tag: Tag,
 }
@@ -123,7 +119,7 @@ static_assert_size!(Pointer, 16);
 // all the Miri types.
 // We have to use `Debug` output for the tag, because `()` does not implement
 // `Display` so we cannot specialize that.
-impl<Tag: fmt::Debug, Id: fmt::Debug> fmt::Debug for Pointer<Tag, Id> {
+impl<Tag: fmt::Debug> fmt::Debug for Pointer<Tag> {
     default fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         if f.alternate() {
             write!(f, "{:#?}+0x{:x}[{:?}]", self.alloc_id, self.offset.bytes(), self.tag)
@@ -133,7 +129,7 @@ impl<Tag: fmt::Debug, Id: fmt::Debug> fmt::Debug for Pointer<Tag, Id> {
     }
 }
 // Specialization for no tag
-impl<Id: fmt::Debug> fmt::Debug for Pointer<(), Id> {
+impl fmt::Debug for Pointer<()> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         if f.alternate() {
             write!(f, "{:#?}+0x{:x}", self.alloc_id, self.offset.bytes())

src/librustc_middle/mir/interpret/value.rs

@@ -89,7 +89,7 @@ impl<'tcx> ConstValue<'tcx> {
 /// of a simple value or a pointer into another `Allocation`
 #[derive(Clone, Copy, Eq, PartialEq, Ord, PartialOrd, RustcEncodable, RustcDecodable, Hash)]
 #[derive(HashStable)]
-pub enum Scalar<Tag = (), Id = AllocId> {
+pub enum Scalar<Tag = ()> {
     /// The raw bytes of a simple value.
     Raw {
         /// The first `size` bytes of `data` are the value.
@@ -101,15 +101,15 @@ pub enum Scalar<Tag = (), Id = AllocId> {
     /// A pointer into an `Allocation`. An `Allocation` in the `memory` module has a list of
     /// relocations, but a `Scalar` is only large enough to contain one, so we just represent the
     /// relocation and its associated offset together as a `Pointer` here.
-    Ptr(Pointer<Tag, Id>),
+    Ptr(Pointer<Tag>),
 }
 
 #[cfg(target_arch = "x86_64")]
 static_assert_size!(Scalar, 24);
 
 // We want the `Debug` output to be readable as it is used by `derive(Debug)` for
 // all the Miri types.
-impl<Tag: fmt::Debug, Id: fmt::Debug> fmt::Debug for Scalar<Tag, Id> {
+impl<Tag: fmt::Debug> fmt::Debug for Scalar<Tag> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             Scalar::Ptr(ptr) => write!(f, "{:?}", ptr),
@@ -542,8 +542,8 @@ impl<Tag> From<Pointer<Tag>> for Scalar<Tag> {
 }
 
 #[derive(Clone, Copy, Eq, PartialEq, RustcEncodable, RustcDecodable, HashStable, Hash)]
-pub enum ScalarMaybeUndef<Tag = (), Id = AllocId> {
-    Scalar(Scalar<Tag, Id>),
+pub enum ScalarMaybeUndef<Tag = ()> {
+    Scalar(Scalar<Tag>),
     Undef,
 }
 
@@ -563,7 +563,7 @@ impl<Tag> From<Pointer<Tag>> for ScalarMaybeUndef<Tag> {
 
 // We want the `Debug` output to be readable as it is used by `derive(Debug)` for
 // all the Miri types.
-impl<Tag: fmt::Debug, Id: fmt::Debug> fmt::Debug for ScalarMaybeUndef<Tag, Id> {
+impl<Tag: fmt::Debug> fmt::Debug for ScalarMaybeUndef<Tag> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             ScalarMaybeUndef::Undef => write!(f, "<uninitialized>"),

src/librustc_middle/ty/relate.rs

@@ -11,6 +11,7 @@ use crate::ty::subst::{GenericArg, GenericArgKind, SubstsRef};
 use crate::ty::{self, Ty, TyCtxt, TypeFoldable};
 use rustc_hir as ast;
 use rustc_hir::def_id::DefId;
+use rustc_span::DUMMY_SP;
 use rustc_target::spec::abi;
 use std::iter;
 use std::rc::Rc;
@@ -507,6 +508,7 @@ pub fn super_relate_consts<R: TypeRelation<'tcx>>(
     a: &'tcx ty::Const<'tcx>,
     b: &'tcx ty::Const<'tcx>,
 ) -> RelateResult<'tcx, &'tcx ty::Const<'tcx>> {
+    debug!("{}.super_relate_consts(a = {:?}, b = {:?})", relation.tag(), a, b);
     let tcx = relation.tcx();
 
     let eagerly_eval = |x: &'tcx ty::Const<'tcx>| {
@@ -561,7 +563,7 @@ pub fn super_relate_consts<R: TypeRelation<'tcx>>(
                     }
                 }
 
-                (a_val @ ConstValue::Slice { .. }, b_val @ ConstValue::Slice { .. }) => {
+                (ConstValue::Slice { .. }, ConstValue::Slice { .. }) => {
                     let a_bytes = get_slice_bytes(&tcx, a_val);
                     let b_bytes = get_slice_bytes(&tcx, b_val);
                     if a_bytes == b_bytes {
@@ -571,7 +573,37 @@ pub fn super_relate_consts<R: TypeRelation<'tcx>>(
                     }
                 }
 
-                // FIXME(const_generics): handle `ConstValue::ByRef`.
+                (ConstValue::ByRef { .. }, ConstValue::ByRef { .. }) => {
+                    match a.ty.kind {
+                        ty::Array(..) | ty::Adt(..) | ty::Tuple(..) => {
+                            let a_destructured = tcx.destructure_const(relation.param_env().and(a));
+                            let b_destructured = tcx.destructure_const(relation.param_env().and(b));
+
+                            // Both the variant and each field have to be equal.
+                            if a_destructured.variant == b_destructured.variant {
+                                for (a_field, b_field) in
+                                    a_destructured.fields.iter().zip(b_destructured.fields.iter())
+                                {
+                                    relation.consts(a_field, b_field)?;
+                                }
+
+                                Ok(a_val)
+                            } else {
+                                Err(TypeError::ConstMismatch(expected_found(relation, &a, &b)))
+                            }
+                        }
+                        // FIXME(const_generics): There are probably some `TyKind`s
+                        // which should be handled here.
+                        _ => {
+                            tcx.sess.delay_span_bug(
+                                DUMMY_SP,
+                                &format!("unexpected consts: a: {:?}, b: {:?}", a, b),
+                            );
+                            Err(TypeError::ConstMismatch(expected_found(relation, &a, &b)))
+                        }
+                    }
+                }
+
                 _ => Err(TypeError::ConstMismatch(expected_found(relation, &a, &b))),
             };
 

src/librustc_mir/const_eval/error.rs

@@ -52,7 +52,7 @@ impl Error for ConstEvalErrKind {}
 /// Should be called only if the error is actually going to to be reported!
 pub fn error_to_const_error<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>>(
     ecx: &InterpCx<'mir, 'tcx, M>,
-    mut error: InterpErrorInfo<'tcx>,
+    error: InterpErrorInfo<'tcx>,
 ) -> ConstEvalErr<'tcx> {
     error.print_backtrace();
     let stacktrace = ecx.generate_stacktrace();

src/librustc_mir/interpret/eval_context.rs

@@ -11,7 +11,7 @@ use rustc_macros::HashStable;
 use rustc_middle::ich::StableHashingContext;
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::{
-    sign_extend, truncate, AllocId, FrameInfo, GlobalId, InterpResult, Pointer, Scalar,
+    sign_extend, truncate, FrameInfo, GlobalId, InterpResult, Pointer, Scalar,
 };
 use rustc_middle::ty::layout::{self, TyAndLayout};
 use rustc_middle::ty::{
@@ -103,16 +103,16 @@ pub enum StackPopCleanup {
 
 /// State of a local variable including a memoized layout
 #[derive(Clone, PartialEq, Eq, HashStable)]
-pub struct LocalState<'tcx, Tag = (), Id = AllocId> {
-    pub value: LocalValue<Tag, Id>,
+pub struct LocalState<'tcx, Tag = ()> {
+    pub value: LocalValue<Tag>,
     /// Don't modify if `Some`, this is only used to prevent computing the layout twice
     #[stable_hasher(ignore)]
     pub layout: Cell<Option<TyAndLayout<'tcx>>>,
 }
 
 /// Current value of a local variable
 #[derive(Copy, Clone, PartialEq, Eq, Debug, HashStable)] // Miri debug-prints these
-pub enum LocalValue<Tag = (), Id = AllocId> {
+pub enum LocalValue<Tag = ()> {
     /// This local is not currently alive, and cannot be used at all.
     Dead,
     /// This local is alive but not yet initialized. It can be written to
@@ -125,7 +125,7 @@ pub enum LocalValue<Tag = (), Id = AllocId> {
     /// This is an optimization over just always having a pointer here;
     /// we can thus avoid doing an allocation when the local just stores
     /// immediate values *and* never has its address taken.
-    Live(Operand<Tag, Id>),
+    Live(Operand<Tag>),
 }
 
 impl<'tcx, Tag: Copy + 'static> LocalState<'tcx, Tag> {

src/librustc_mir/interpret/operand.rs

@@ -15,8 +15,8 @@ use rustc_target::abi::{Abi, DiscriminantKind, HasDataLayout, Integer, LayoutOf,
 use rustc_target::abi::{VariantIdx, Variants};
 
 use super::{
-    from_known_layout, sign_extend, truncate, AllocId, ConstValue, GlobalId, InterpCx,
-    InterpResult, MPlaceTy, Machine, MemPlace, Place, PlaceTy, Pointer, Scalar, ScalarMaybeUndef,
+    from_known_layout, sign_extend, truncate, ConstValue, GlobalId, InterpCx, InterpResult,
+    MPlaceTy, Machine, MemPlace, Place, PlaceTy, Pointer, Scalar, ScalarMaybeUndef,
 };
 
 /// An `Immediate` represents a single immediate self-contained Rust value.
@@ -27,9 +27,9 @@ use super::{
 /// In particular, thanks to `ScalarPair`, arithmetic operations and casts can be entirely
 /// defined on `Immediate`, and do not have to work with a `Place`.
 #[derive(Copy, Clone, Debug, PartialEq, Eq, HashStable, Hash)]
-pub enum Immediate<Tag = (), Id = AllocId> {
-    Scalar(ScalarMaybeUndef<Tag, Id>),
-    ScalarPair(ScalarMaybeUndef<Tag, Id>, ScalarMaybeUndef<Tag, Id>),
+pub enum Immediate<Tag = ()> {
+    Scalar(ScalarMaybeUndef<Tag>),
+    ScalarPair(ScalarMaybeUndef<Tag>, ScalarMaybeUndef<Tag>),
 }
 
 impl<Tag> From<ScalarMaybeUndef<Tag>> for Immediate<Tag> {
@@ -145,9 +145,9 @@ impl<'tcx, Tag> ::std::ops::Deref for ImmTy<'tcx, Tag> {
 /// or still in memory. The latter is an optimization, to delay reading that chunk of
 /// memory and to avoid having to store arbitrary-sized data here.
 #[derive(Copy, Clone, Debug, PartialEq, Eq, HashStable, Hash)]
-pub enum Operand<Tag = (), Id = AllocId> {
-    Immediate(Immediate<Tag, Id>),
-    Indirect(MemPlace<Tag, Id>),
+pub enum Operand<Tag = ()> {
+    Immediate(Immediate<Tag>),
+    Indirect(MemPlace<Tag>),
 }
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]

src/librustc_mir/interpret/place.rs

@@ -20,9 +20,9 @@ use super::{
 
 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable)]
 /// Information required for the sound usage of a `MemPlace`.
-pub enum MemPlaceMeta<Tag = (), Id = AllocId> {
+pub enum MemPlaceMeta<Tag = ()> {
     /// The unsized payload (e.g. length for slices or vtable pointer for trait objects).
-    Meta(Scalar<Tag, Id>),
+    Meta(Scalar<Tag>),
     /// `Sized` types or unsized `extern type`
     None,
     /// The address of this place may not be taken. This protects the `MemPlace` from coming from
@@ -32,8 +32,8 @@ pub enum MemPlaceMeta<Tag = (), Id = AllocId> {
     Poison,
 }
 
-impl<Tag, Id> MemPlaceMeta<Tag, Id> {
-    pub fn unwrap_meta(self) -> Scalar<Tag, Id> {
+impl<Tag> MemPlaceMeta<Tag> {
+    pub fn unwrap_meta(self) -> Scalar<Tag> {
         match self {
             Self::Meta(s) => s,
             Self::None | Self::Poison => {
@@ -47,9 +47,7 @@ impl<Tag, Id> MemPlaceMeta<Tag, Id> {
             Self::None | Self::Poison => false,
         }
     }
-}
 
-impl<Tag> MemPlaceMeta<Tag> {
     pub fn erase_tag(self) -> MemPlaceMeta<()> {
         match self {
             Self::Meta(s) => MemPlaceMeta::Meta(s.erase_tag()),
@@ -60,22 +58,22 @@ impl<Tag> MemPlaceMeta<Tag> {
 }
 
 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable)]
-pub struct MemPlace<Tag = (), Id = AllocId> {
+pub struct MemPlace<Tag = ()> {
     /// A place may have an integral pointer for ZSTs, and since it might
     /// be turned back into a reference before ever being dereferenced.
     /// However, it may never be undef.
-    pub ptr: Scalar<Tag, Id>,
+    pub ptr: Scalar<Tag>,
     pub align: Align,
     /// Metadata for unsized places. Interpretation is up to the type.
     /// Must not be present for sized types, but can be missing for unsized types
     /// (e.g., `extern type`).
-    pub meta: MemPlaceMeta<Tag, Id>,
+    pub meta: MemPlaceMeta<Tag>,
 }
 
 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable)]
-pub enum Place<Tag = (), Id = AllocId> {
+pub enum Place<Tag = ()> {
     /// A place referring to a value allocated in the `Memory` system.
-    Ptr(MemPlace<Tag, Id>),
+    Ptr(MemPlace<Tag>),
 
     /// To support alloc-free locals, we are able to write directly to a local.
     /// (Without that optimization, we'd just always be a `MemPlace`.)

src/librustc_trait_selection/traits/util.rs

@@ -217,7 +217,6 @@ pub fn impl_trait_ref_and_oblig<'a, 'tcx>(
     (impl_trait_ref, impl_obligations)
 }
 
-/// See [`super::obligations_for_generics`].
 pub fn predicates_for_generics<'tcx>(
     cause: ObligationCause<'tcx>,
     recursion_depth: usize,

src/librustc_typeck/check/coercion.rs

@@ -107,6 +107,7 @@ fn coerce_mutbls<'tcx>(
     }
 }
 
+/// Do not require any adjustments, i.e. coerce `x -> x`.
 fn identity(_: Ty<'_>) -> Vec<Adjustment<'_>> {
     vec![]
 }
@@ -115,6 +116,7 @@ fn simple(kind: Adjust<'tcx>) -> impl FnOnce(Ty<'tcx>) -> Vec<Adjustment<'tcx>>
     move |target| vec![Adjustment { kind, target }]
 }
 
+/// This always returns `Ok(...)`.
 fn success<'tcx>(
     adj: Vec<Adjustment<'tcx>>,
     target: Ty<'tcx>,
@@ -133,6 +135,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
     }
 
     pub fn unify(&self, a: Ty<'tcx>, b: Ty<'tcx>) -> InferResult<'tcx, Ty<'tcx>> {
+        debug!("unify(a: {:?}, b: {:?}, use_lub: {})", a, b, self.use_lub);
         self.commit_if_ok(|_| {
             if self.use_lub {
                 self.at(&self.cause, self.fcx.param_env).lub(b, a)

src/test/ui/const-generics/different_byref.rs

@@ -0,0 +1,11 @@
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+struct Const<const V: [usize; 1]> {}
+
+fn main() {
+    let mut x = Const::<{ [3] }> {};
+    x = Const::<{ [4] }> {};
+    //~^ ERROR mismatched types
+
+}

src/test/ui/const-generics/different_byref.stderr

@@ -0,0 +1,20 @@
+warning: the feature `const_generics` is incomplete and may cause the compiler to crash
+  --> $DIR/different_byref.rs:1:12
+   |
+LL | #![feature(const_generics)]
+   |            ^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+
+error[E0308]: mismatched types
+  --> $DIR/different_byref.rs:8:9
+   |
+LL |     x = Const::<{ [4] }> {};
+   |         ^^^^^^^^^^^^^^^^^^^ expected `3usize`, found `4usize`
+   |
+   = note: expected struct `Const<[3usize]>`
+              found struct `Const<[4usize]>`
+
+error: aborting due to previous error; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0308`.

src/test/ui/const-generics/issues/issue-68615-adt.rs

@@ -0,0 +1,11 @@
+// check-pass
+#![feature(const_generics)]
+#![allow(incomplete_features)]
+
+struct Const<const V: [usize; 0]> {}
+type MyConst = Const<{ [] }>;
+
+fn main() {
+    let _x = Const::<{ [] }> {};
+    let _y = MyConst {};
+}

src/test/ui/const-generics/issues/issue-68615-array.rs

@@ -0,0 +1,11 @@
+// check-pass
+#![feature(const_generics)]
+#![allow(incomplete_features)]
+
+struct Foo<const V: [usize; 0] > {}
+
+type MyFoo = Foo<{ [] }>;
+
+fn main() {
+    let _ = Foo::<{ [] }> {};
+}