Rollup of 7 pull requests

src/libcore/ops/index.rs

@@ -65,6 +65,7 @@ pub trait Index<Idx: ?Sized> {
 
     /// Performs the indexing (`container[index]`) operation.
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[cfg_attr(not(bootstrap), track_caller)]
     fn index(&self, index: Idx) -> &Self::Output;
 }
 
@@ -166,5 +167,6 @@ see chapter in The Book <https://doc.rust-lang.org/book/ch08-02-strings.html#ind
 pub trait IndexMut<Idx: ?Sized>: Index<Idx> {
     /// Performs the mutable indexing (`container[index]`) operation.
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[cfg_attr(not(bootstrap), track_caller)]
     fn index_mut(&mut self, index: Idx) -> &mut Self::Output;
 }

src/libcore/slice/mod.rs

@@ -2306,6 +2306,7 @@ impl<T> [T] {
     /// assert_eq!(&bytes, b"Hello, Wello!");
     /// ```
     #[stable(feature = "copy_within", since = "1.37.0")]
+    #[track_caller]
     pub fn copy_within<R: ops::RangeBounds<usize>>(&mut self, src: R, dest: usize)
     where
         T: Copy,
@@ -2721,18 +2722,21 @@ where
 
 #[inline(never)]
 #[cold]
+#[track_caller]
 fn slice_index_len_fail(index: usize, len: usize) -> ! {
     panic!("index {} out of range for slice of length {}", index, len);
 }
 
 #[inline(never)]
 #[cold]
+#[track_caller]
 fn slice_index_order_fail(index: usize, end: usize) -> ! {
     panic!("slice index starts at {} but ends at {}", index, end);
 }
 
 #[inline(never)]
 #[cold]
+#[track_caller]
 fn slice_index_overflow_fail() -> ! {
     panic!("attempted to index slice up to maximum usize");
 }
@@ -2804,11 +2808,13 @@ pub trait SliceIndex<T: ?Sized>: private_slice_index::Sealed {
     /// Returns a shared reference to the output at this location, panicking
     /// if out of bounds.
     #[unstable(feature = "slice_index_methods", issue = "none")]
+    #[cfg_attr(not(bootstrap), track_caller)]
     fn index(self, slice: &T) -> &Self::Output;
 
     /// Returns a mutable reference to the output at this location, panicking
     /// if out of bounds.
     #[unstable(feature = "slice_index_methods", issue = "none")]
+    #[cfg_attr(not(bootstrap), track_caller)]
     fn index_mut(self, slice: &mut T) -> &mut Self::Output;
 }
 

src/libcore/str/mod.rs

@@ -1794,6 +1794,7 @@ mod traits {
 
     #[inline(never)]
     #[cold]
+    #[track_caller]
     fn str_index_overflow_fail() -> ! {
         panic!("attempted to index str up to maximum usize");
     }
@@ -2185,6 +2186,7 @@ fn truncate_to_char_boundary(s: &str, mut max: usize) -> (bool, &str) {
 
 #[inline(never)]
 #[cold]
+#[track_caller]
 fn slice_error_fail(s: &str, begin: usize, end: usize) -> ! {
     const MAX_DISPLAY_LENGTH: usize = 256;
     let (truncated, s_trunc) = truncate_to_char_boundary(s, MAX_DISPLAY_LENGTH);

src/librustc/dep_graph/dep_node.rs

@@ -59,7 +59,7 @@ use crate::traits::query::{
     CanonicalTypeOpAscribeUserTypeGoal, CanonicalTypeOpEqGoal, CanonicalTypeOpNormalizeGoal,
     CanonicalTypeOpProvePredicateGoal, CanonicalTypeOpSubtypeGoal,
 };
-use crate::ty::subst::SubstsRef;
+use crate::ty::subst::{GenericArg, SubstsRef};
 use crate::ty::{self, ParamEnvAnd, Ty, TyCtxt};
 
 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_INDEX};

src/librustc/mir/interpret/error.rs

@@ -453,9 +453,6 @@ pub enum UnsupportedOpInfo {
     ReadForeignStatic(DefId),
     /// Could not find MIR for a function.
     NoMirFor(DefId),
-    /// Modified a static during const-eval.
-    /// FIXME: move this to `ConstEvalErrKind` through a machine hook.
-    ModifiedStatic,
     /// Encountered a pointer where we needed raw bytes.
     ReadPointerAsBytes,
     /// Encountered raw bytes where we needed a pointer.
@@ -471,12 +468,6 @@ impl fmt::Debug for UnsupportedOpInfo {
                 write!(f, "tried to read from foreign (extern) static {:?}", did)
             }
             NoMirFor(did) => write!(f, "could not load MIR for {:?}", did),
-            ModifiedStatic => write!(
-                f,
-                "tried to modify a static's initial value from another static's \
-                    initializer"
-            ),
-
             ReadPointerAsBytes => write!(f, "unable to turn pointer into raw bytes",),
             ReadBytesAsPointer => write!(f, "unable to turn bytes into a pointer"),
         }

src/librustc/query/mod.rs

@@ -9,7 +9,7 @@ use crate::traits::query::{
 };
 use crate::ty::query::queries;
 use crate::ty::query::QueryDescription;
-use crate::ty::subst::SubstsRef;
+use crate::ty::subst::{GenericArg, SubstsRef};
 use crate::ty::{self, ParamEnvAnd, Ty, TyCtxt};
 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId};
 
@@ -1114,10 +1114,10 @@ rustc_queries! {
         }
 
         /// Do not call this query directly: invoke `normalize_erasing_regions` instead.
-        query normalize_ty_after_erasing_regions(
-            goal: ParamEnvAnd<'tcx, Ty<'tcx>>
-        ) -> Ty<'tcx> {
-            desc { "normalizing `{:?}`", goal }
+        query normalize_generic_arg_after_erasing_regions(
+            goal: ParamEnvAnd<'tcx, GenericArg<'tcx>>
+        ) -> GenericArg<'tcx> {
+            desc { "normalizing `{}`", goal.value }
         }
 
         query implied_outlives_bounds(

src/librustc/traits/structural_impls.rs

@@ -273,6 +273,20 @@ impl<'tcx> TypeVisitor<'tcx> for BoundNamesCollector {
         t.super_visit_with(self)
     }
 
+    fn visit_const(&mut self, c: &'tcx ty::Const<'tcx>) -> bool {
+        match c.val {
+            ty::ConstKind::Bound(debruijn, bound_var) if debruijn == self.binder_index => {
+                self.types.insert(
+                    bound_var.as_u32(),
+                    Symbol::intern(&format!("^{}", bound_var.as_u32())),
+                );
+            }
+            _ => (),
+        }
+
+        c.super_visit_with(self)
+    }
+
     fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool {
         match r {
             ty::ReLateBound(index, br) if *index == self.binder_index => match br {

src/librustc/ty/context.rs

@@ -984,6 +984,7 @@ pub struct GlobalCtxt<'tcx> {
     /// Stores the value of constants (and deduplicates the actual memory)
     allocation_interner: ShardedHashMap<&'tcx Allocation, ()>,
 
+    /// Stores memory for globals (statics/consts).
     pub alloc_map: Lock<interpret::AllocMap<'tcx>>,
 
     layout_interner: ShardedHashMap<&'tcx LayoutDetails, ()>,

src/librustc/ty/fold.rs

@@ -978,17 +978,27 @@ impl<'tcx> TypeVisitor<'tcx> for LateBoundRegionsCollector {
         // ignore the inputs to a projection, as they may not appear
         // in the normalized form
         if self.just_constrained {
-            match t.kind {
-                ty::Projection(..) | ty::Opaque(..) => {
-                    return false;
-                }
-                _ => {}
+            if let ty::Projection(..) | ty::Opaque(..) = t.kind {
+                return false;
             }
         }
 
         t.super_visit_with(self)
     }
 
+    fn visit_const(&mut self, c: &'tcx ty::Const<'tcx>) -> bool {
+        // if we are only looking for "constrained" region, we have to
+        // ignore the inputs of an unevaluated const, as they may not appear
+        // in the normalized form
+        if self.just_constrained {
+            if let ty::ConstKind::Unevaluated(..) = c.val {
+                return false;
+            }
+        }
+
+        c.super_visit_with(self)
+    }
+
     fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool {
         if let ty::ReLateBound(debruijn, br) = *r {
             if debruijn == self.current_index {

src/librustc/ty/normalize_erasing_regions.rs

@@ -4,8 +4,8 @@
 //!
 //! The methods in this file use a `TypeFolder` to recursively process
 //! contents, invoking the underlying
-//! `normalize_ty_after_erasing_regions` query for each type found
-//! within. (This underlying query is what is cached.)
+//! `normalize_generic_arg_after_erasing_regions` query for each type
+//! or constant found within. (This underlying query is what is cached.)
 
 use crate::ty::fold::{TypeFoldable, TypeFolder};
 use crate::ty::subst::{Subst, SubstsRef};
@@ -94,6 +94,12 @@ impl TypeFolder<'tcx> for NormalizeAfterErasingRegionsFolder<'tcx> {
     }
 
     fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
-        self.tcx.normalize_ty_after_erasing_regions(self.param_env.and(ty))
+        let arg = self.param_env.and(ty.into());
+        self.tcx.normalize_generic_arg_after_erasing_regions(arg).expect_ty()
+    }
+
+    fn fold_const(&mut self, c: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
+        let arg = self.param_env.and(c.into());
+        self.tcx.normalize_generic_arg_after_erasing_regions(arg).expect_const()
     }
 }

src/librustc/ty/query/keys.rs

@@ -5,7 +5,7 @@ use crate::mir;
 use crate::traits;
 use crate::ty::fast_reject::SimplifiedType;
 use crate::ty::query::caches::DefaultCacheSelector;
-use crate::ty::subst::SubstsRef;
+use crate::ty::subst::{GenericArg, SubstsRef};
 use crate::ty::{self, Ty, TyCtxt};
 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LOCAL_CRATE};
 use rustc_span::symbol::Symbol;
@@ -194,6 +194,17 @@ impl<'tcx> Key for ty::PolyTraitRef<'tcx> {
     }
 }
 
+impl<'tcx> Key for GenericArg<'tcx> {
+    type CacheSelector = DefaultCacheSelector;
+
+    fn query_crate(&self) -> CrateNum {
+        LOCAL_CRATE
+    }
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
 impl<'tcx> Key for &'tcx ty::Const<'tcx> {
     type CacheSelector = DefaultCacheSelector;
 

src/librustc/ty/query/mod.rs

@@ -31,7 +31,7 @@ use crate::traits::specialization_graph;
 use crate::traits::Clauses;
 use crate::traits::{self, Vtable};
 use crate::ty::steal::Steal;
-use crate::ty::subst::SubstsRef;
+use crate::ty::subst::{GenericArg, SubstsRef};
 use crate::ty::util::AlwaysRequiresDrop;
 use crate::ty::{self, AdtSizedConstraint, CrateInherentImpls, ParamEnvAnd, Ty, TyCtxt};
 use crate::util::common::ErrorReported;

src/librustc/ty/subst.rs

@@ -128,6 +128,14 @@ impl<'tcx> GenericArg<'tcx> {
             _ => bug!("expected a type, but found another kind"),
         }
     }
+
+    /// Unpack the `GenericArg` as a const when it is known certainly to be a const.
+    pub fn expect_const(self) -> &'tcx ty::Const<'tcx> {
+        match self.unpack() {
+            GenericArgKind::Const(c) => c,
+            _ => bug!("expected a const, but found another kind"),
+        }
+    }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for GenericArg<'a> {

src/librustc_error_codes/error_codes/E0436.md

@@ -1,5 +1,4 @@
-The functional record update syntax is only allowed for structs. (Struct-like
-enum variants don't qualify, for example.)
+The functional record update syntax was used on something other than a struct.
 
 Erroneous code example:
 
@@ -24,7 +23,9 @@ fn one_up_competitor(competitor_frequency: PublicationFrequency)
 }
 ```
 
-Rewrite the expression without functional record update syntax:
+The functional record update syntax is only allowed for structs (struct-like
+enum variants don't qualify, for example). To fix the previous code, rewrite the
+expression without functional record update syntax:
 
 ```
 enum PublicationFrequency {

src/librustc_error_codes/error_codes/E0454.md

@@ -1,4 +1,6 @@
-A link name was given with an empty name. Erroneous code example:
+A link name was given with an empty name.
+
+Erroneous code example:
 
 ```compile_fail,E0454
 #[link(name = "")] extern {}

src/librustc_mir/const_eval/error.rs

@@ -12,6 +12,7 @@ use crate::interpret::{ConstEvalErr, InterpErrorInfo, Machine};
 pub enum ConstEvalErrKind {
     NeedsRfc(String),
     ConstAccessesStatic,
+    ModifiedGlobal,
     AssertFailure(AssertKind<u64>),
     Panic { msg: Symbol, line: u32, col: u32, file: Symbol },
 }
@@ -33,6 +34,9 @@ impl fmt::Display for ConstEvalErrKind {
                 write!(f, "\"{}\" needs an rfc before being allowed inside constants", msg)
             }
             ConstAccessesStatic => write!(f, "constant accesses static"),
+            ModifiedGlobal => {
+                write!(f, "modifying a static's initial value from another static's initializer")
+            }
             AssertFailure(ref msg) => write!(f, "{:?}", msg),
             Panic { msg, line, col, file } => {
                 write!(f, "the evaluated program panicked at '{}', {}:{}:{}", msg, file, line, col)

src/librustc_mir/const_eval/machine.rs

@@ -8,8 +8,9 @@ use std::hash::Hash;
 use rustc_data_structures::fx::FxHashMap;
 
 use rustc::mir::AssertMessage;
-use rustc_span::source_map::Span;
+use rustc_ast::ast::Mutability;
 use rustc_span::symbol::Symbol;
+use rustc_span::{def_id::DefId, Span};
 
 use crate::interpret::{
     self, AllocId, Allocation, GlobalId, ImmTy, InterpCx, InterpResult, Memory, MemoryKind, OpTy,
@@ -167,7 +168,7 @@ impl interpret::MayLeak for ! {
 }
 
 impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter {
-    type MemoryKinds = !;
+    type MemoryKind = !;
     type PointerTag = ();
     type ExtraFnVal = !;
 
@@ -177,7 +178,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter {
 
     type MemoryMap = FxHashMap<AllocId, (MemoryKind<!>, Allocation)>;
 
-    const STATIC_KIND: Option<!> = None; // no copying of statics allowed
+    const GLOBAL_KIND: Option<!> = None; // no copying of globals allowed
 
     // We do not check for alignment to avoid having to carry an `Align`
     // in `ConstValue::ByRef`.
@@ -317,7 +318,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter {
     }
 
     #[inline(always)]
-    fn tag_static_base_pointer(_memory_extra: &MemoryExtra, _id: AllocId) -> Self::PointerTag {}
+    fn tag_global_base_pointer(_memory_extra: &MemoryExtra, _id: AllocId) -> Self::PointerTag {}
 
     fn box_alloc(
         _ecx: &mut InterpCx<'mir, 'tcx, Self>,
@@ -345,11 +346,19 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter {
         Ok(())
     }
 
-    fn before_access_static(
+    fn before_access_global(
         memory_extra: &MemoryExtra,
-        _allocation: &Allocation,
+        alloc_id: AllocId,
+        allocation: &Allocation,
+        def_id: Option<DefId>,
+        is_write: bool,
     ) -> InterpResult<'tcx> {
-        if memory_extra.can_access_statics {
+        if is_write && allocation.mutability == Mutability::Not {
+            Err(err_ub!(WriteToReadOnly(alloc_id)).into())
+        } else if is_write {
+            Err(ConstEvalErrKind::ModifiedGlobal.into())
+        } else if memory_extra.can_access_statics || def_id.is_none() {
+            // `def_id.is_none()` indicates this is not a static, but a const or so.
             Ok(())
         } else {
             Err(ConstEvalErrKind::ConstAccessesStatic.into())

src/librustc_mir/interpret/eval_context.rs

@@ -253,8 +253,8 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     /// This represents a *direct* access to that memory, as opposed to access
     /// through a pointer that was created by the program.
     #[inline(always)]
-    pub fn tag_static_base_pointer(&self, ptr: Pointer) -> Pointer<M::PointerTag> {
-        self.memory.tag_static_base_pointer(ptr)
+    pub fn tag_global_base_pointer(&self, ptr: Pointer) -> Pointer<M::PointerTag> {
+        self.memory.tag_global_base_pointer(ptr)
     }
 
     #[inline(always)]