Auto merge of #36491 - Manishearth:rollup, r=Manishearth

Rollup of 9 pull requests

- Successful merges: #36384, #36405, #36425, #36429, #36438, #36454, #36459, #36461, #36463
- Failed merges: #36444

Author: bors

Diff for: src/libcore/clone.rs

@@ -113,10 +113,23 @@ pub trait Clone : Sized {
     }
 }
 
-// FIXME(aburka): this method is used solely by #[derive] to
-// assert that every component of a type implements Clone.
+// FIXME(aburka): these structs are used solely by #[derive] to
+// assert that every component of a type implements Clone or Copy.
 //
-// This should never be called by user code.
+// These structs should never appear in user code.
+#[doc(hidden)]
+#[allow(missing_debug_implementations)]
+#[unstable(feature = "derive_clone_copy",
+           reason = "deriving hack, should not be public",
+           issue = "0")]
+pub struct AssertParamIsClone<T: Clone + ?Sized> { _field: ::marker::PhantomData<T> }
+#[doc(hidden)]
+#[allow(missing_debug_implementations)]
+#[unstable(feature = "derive_clone_copy",
+           reason = "deriving hack, should not be public",
+           issue = "0")]
+pub struct AssertParamIsCopy<T: Copy + ?Sized> { _field: ::marker::PhantomData<T> }
+#[cfg(stage0)]
 #[doc(hidden)]
 #[inline(always)]
 #[unstable(feature = "derive_clone_copy",

Diff for: src/libcore/cmp.rs

@@ -129,7 +129,7 @@ pub trait PartialEq<Rhs: ?Sized = Self> {
 /// This trait can be used with `#[derive]`. When `derive`d, because `Eq` has
 /// no extra methods, it is only informing the compiler that this is an
 /// equivalence relation rather than a partial equivalence relation. Note that
-/// the `derive` strategy requires all fields are `PartialEq`, which isn't
+/// the `derive` strategy requires all fields are `Eq`, which isn't
 /// always desired.
 ///
 /// ## How can I implement `Eq`?
@@ -165,6 +165,17 @@ pub trait Eq: PartialEq<Self> {
     fn assert_receiver_is_total_eq(&self) {}
 }
 
+// FIXME: this struct is used solely by #[derive] to
+// assert that every component of a type implements Eq.
+//
+// This struct should never appear in user code.
+#[doc(hidden)]
+#[allow(missing_debug_implementations)]
+#[unstable(feature = "derive_eq",
+           reason = "deriving hack, should not be public",
+           issue = "0")]
+pub struct AssertParamIsEq<T: Eq + ?Sized> { _field: ::marker::PhantomData<T> }
+
 /// An `Ordering` is the result of a comparison between two values.
 ///
 /// # Examples

Diff for: src/libcore/slice.rs

@@ -520,8 +520,8 @@ impl<T> ops::Index<usize> for [T] {
     type Output = T;
 
     fn index(&self, index: usize) -> &T {
-        assert!(index < self.len());
-        unsafe { self.get_unchecked(index) }
+        // NB built-in indexing
+        &(*self)[index]
     }
 }
 
@@ -530,8 +530,8 @@ impl<T> ops::Index<usize> for [T] {
 impl<T> ops::IndexMut<usize> for [T] {
     #[inline]
     fn index_mut(&mut self, index: usize) -> &mut T {
-        assert!(index < self.len());
-        unsafe { self.get_unchecked_mut(index) }
+        // NB built-in indexing
+        &mut (*self)[index]
     }
 }
 

Diff for: src/librustc/infer/mod.rs

@@ -830,6 +830,33 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
         result.map(move |t| InferOk { value: t, obligations: fields.obligations })
     }
 
+    // Clear the "obligations in snapshot" flag, invoke the closure,
+    // then restore the flag to its original value. This flag is a
+    // debugging measure designed to detect cases where we start a
+    // snapshot, create type variables, register obligations involving
+    // those type variables in the fulfillment cx, and then have to
+    // unroll the snapshot, leaving "dangling type variables" behind.
+    // In such cases, the flag will be set by the fulfillment cx, and
+    // an assertion will fail when rolling the snapshot back.  Very
+    // useful, much better than grovelling through megabytes of
+    // RUST_LOG output.
+    //
+    // HOWEVER, in some cases the flag is wrong. In particular, we
+    // sometimes create a "mini-fulfilment-cx" in which we enroll
+    // obligations. As long as this fulfillment cx is fully drained
+    // before we return, this is not a problem, as there won't be any
+    // escaping obligations in the main cx. In those cases, you can
+    // use this function.
+    pub fn save_and_restore_obligations_in_snapshot_flag<F, R>(&self, func: F) -> R
+        where F: FnOnce(&Self) -> R
+    {
+        let flag = self.obligations_in_snapshot.get();
+        self.obligations_in_snapshot.set(false);
+        let result = func(self);
+        self.obligations_in_snapshot.set(flag);
+        result
+    }
+
     fn start_snapshot(&self) -> CombinedSnapshot {
         debug!("start_snapshot()");
 

Diff for: src/librustc/middle/cstore.rs

@@ -39,6 +39,7 @@ use std::rc::Rc;
 use std::path::PathBuf;
 use syntax::ast;
 use syntax::attr;
+use syntax::ext::base::LoadedMacro;
 use syntax::ptr::P;
 use syntax::parse::token::InternedString;
 use syntax_pos::Span;
@@ -492,6 +493,9 @@ impl<'tcx> CrateStore<'tcx> for DummyCrateStore {
     fn metadata_encoding_version(&self) -> &[u8] { bug!("metadata_encoding_version") }
 }
 
+pub trait MacroLoader {
+     fn load_crate(&mut self, extern_crate: &ast::Item, allows_macros: bool) -> Vec<LoadedMacro>;
+}
 
 /// Metadata encoding and decoding can make use of thread-local encoding and
 /// decoding contexts. These allow implementers of serialize::Encodable and

Diff for: src/librustc/session/mod.rs

@@ -21,7 +21,7 @@ use util::nodemap::{NodeMap, FnvHashMap};
 use util::common::duration_to_secs_str;
 use mir::transform as mir_pass;
 
-use syntax::ast::{NodeId, Name};
+use syntax::ast::NodeId;
 use errors::{self, DiagnosticBuilder};
 use errors::emitter::{Emitter, EmitterWriter};
 use syntax::json::JsonEmitter;
@@ -39,7 +39,7 @@ use llvm;
 
 use std::path::{Path, PathBuf};
 use std::cell::{self, Cell, RefCell};
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
 use std::env;
 use std::ffi::CString;
 use std::rc::Rc;
@@ -96,10 +96,6 @@ pub struct Session {
     pub injected_allocator: Cell<Option<ast::CrateNum>>,
     pub injected_panic_runtime: Cell<Option<ast::CrateNum>>,
 
-    /// Names of all bang-style macros and syntax extensions
-    /// available in this crate
-    pub available_macros: RefCell<HashSet<Name>>,
-
     /// Map from imported macro spans (which consist of
     /// the localized span for the macro body) to the
     /// macro name and defintion span in the source crate.
@@ -552,7 +548,6 @@ pub fn build_session_(sopts: config::Options,
         next_node_id: Cell::new(1),
         injected_allocator: Cell::new(None),
         injected_panic_runtime: Cell::new(None),
-        available_macros: RefCell::new(HashSet::new()),
         imported_macro_spans: RefCell::new(HashMap::new()),
         incr_comp_session: RefCell::new(IncrCompSession::NotInitialized),
         perf_stats: PerfStats {

Diff for: src/librustc/traits/specialize/mod.rs

@@ -203,32 +203,34 @@ fn fulfill_implication<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
     // attempt to prove all of the predicates for impl2 given those for impl1
     // (which are packed up in penv)
 
-    let mut fulfill_cx = FulfillmentContext::new();
-    for oblig in obligations.into_iter() {
-        fulfill_cx.register_predicate_obligation(&infcx, oblig);
-    }
-    match fulfill_cx.select_all_or_error(infcx) {
-        Err(errors) => {
-            // no dice!
-            debug!("fulfill_implication: for impls on {:?} and {:?}, could not fulfill: {:?} given \
-                    {:?}",
-                   source_trait_ref,
-                   target_trait_ref,
-                   errors,
-                   infcx.parameter_environment.caller_bounds);
-            Err(())
+    infcx.save_and_restore_obligations_in_snapshot_flag(|infcx| {
+        let mut fulfill_cx = FulfillmentContext::new();
+        for oblig in obligations.into_iter() {
+            fulfill_cx.register_predicate_obligation(&infcx, oblig);
         }
+        match fulfill_cx.select_all_or_error(infcx) {
+            Err(errors) => {
+                // no dice!
+                debug!("fulfill_implication: for impls on {:?} and {:?}, \
+                        could not fulfill: {:?} given {:?}",
+                       source_trait_ref,
+                       target_trait_ref,
+                       errors,
+                       infcx.parameter_environment.caller_bounds);
+                Err(())
+            }
 
-        Ok(()) => {
-            debug!("fulfill_implication: an impl for {:?} specializes {:?}",
-                   source_trait_ref,
-                   target_trait_ref);
+            Ok(()) => {
+                debug!("fulfill_implication: an impl for {:?} specializes {:?}",
+                       source_trait_ref,
+                       target_trait_ref);
 
-            // Now resolve the *substitution* we built for the target earlier, replacing
-            // the inference variables inside with whatever we got from fulfillment.
-            Ok(infcx.resolve_type_vars_if_possible(&target_substs))
+                // Now resolve the *substitution* we built for the target earlier, replacing
+                // the inference variables inside with whatever we got from fulfillment.
+                Ok(infcx.resolve_type_vars_if_possible(&target_substs))
+            }
         }
-    }
+    })
 }
 
 pub struct SpecializesCache {

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

@@ -1303,7 +1303,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
     }
 
     pub fn mk_trait(self, mut obj: TraitObject<'tcx>) -> Ty<'tcx> {
-        obj.projection_bounds.sort_by(|a, b| a.sort_key().cmp(&b.sort_key()));
+        obj.projection_bounds.sort_by_key(|b| b.sort_key(self));
         self.mk_ty(TyTrait(box obj))
     }
 

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

@@ -1018,10 +1018,6 @@ impl<'tcx> PolyProjectionPredicate<'tcx> {
     pub fn item_name(&self) -> Name {
         self.0.projection_ty.item_name // safe to skip the binder to access a name
     }
-
-    pub fn sort_key(&self) -> (DefId, Name) {
-        self.0.projection_ty.sort_key()
-    }
 }
 
 pub trait ToPolyTraitRef<'tcx> {

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

@@ -23,7 +23,7 @@ use std::mem;
 use std::ops;
 use syntax::abi;
 use syntax::ast::{self, Name};
-use syntax::parse::token::keywords;
+use syntax::parse::token::{keywords, InternedString};
 
 use serialize::{Decodable, Decoder, Encodable, Encoder};
 
@@ -440,12 +440,6 @@ pub struct ProjectionTy<'tcx> {
     pub item_name: Name,
 }
 
-impl<'tcx> ProjectionTy<'tcx> {
-    pub fn sort_key(&self) -> (DefId, Name) {
-        (self.trait_ref.def_id, self.item_name)
-    }
-}
-
 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
 pub struct BareFnTy<'tcx> {
     pub unsafety: hir::Unsafety,
@@ -738,8 +732,17 @@ impl<'a, 'tcx, 'gcx> PolyExistentialProjection<'tcx> {
         self.0.item_name // safe to skip the binder to access a name
     }
 
-    pub fn sort_key(&self) -> (DefId, Name) {
-        (self.0.trait_ref.def_id, self.0.item_name)
+    pub fn sort_key(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> (u64, InternedString) {
+        // We want something here that is stable across crate boundaries.
+        // The DefId isn't but the `deterministic_hash` of the corresponding
+        // DefPath is.
+        let trait_def = tcx.lookup_trait_def(self.0.trait_ref.def_id);
+        let def_path_hash = trait_def.def_path_hash;
+
+        // An `ast::Name` is also not stable (it's just an index into an
+        // interning table), so map to the corresponding `InternedString`.
+        let item_name = self.0.item_name.as_str();
+        (def_path_hash, item_name)
     }
 
     pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,

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

@@ -70,15 +70,20 @@ pub struct TraitDef<'tcx> {
     pub specialization_graph: RefCell<traits::specialization_graph::Graph>,
 
     /// Various flags
-    pub flags: Cell<TraitFlags>
+    pub flags: Cell<TraitFlags>,
+
+    /// The ICH of this trait's DefPath, cached here so it doesn't have to be
+    /// recomputed all the time.
+    pub def_path_hash: u64,
 }
 
 impl<'a, 'gcx, 'tcx> TraitDef<'tcx> {
     pub fn new(unsafety: hir::Unsafety,
                paren_sugar: bool,
                generics: &'tcx ty::Generics<'tcx>,
                trait_ref: ty::TraitRef<'tcx>,
-               associated_type_names: Vec<Name>)
+               associated_type_names: Vec<Name>,
+               def_path_hash: u64)
                -> TraitDef<'tcx> {
         TraitDef {
             paren_sugar: paren_sugar,
@@ -90,6 +95,7 @@ impl<'a, 'gcx, 'tcx> TraitDef<'tcx> {
             blanket_impls: RefCell::new(vec![]),
             flags: Cell::new(ty::TraitFlags::NO_TRAIT_FLAGS),
             specialization_graph: RefCell::new(traits::specialization_graph::Graph::new()),
+            def_path_hash: def_path_hash,
         }
     }
 

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

@@ -411,15 +411,11 @@ impl<'a, 'gcx, 'tcx> TypeIdHasher<'a, 'gcx, 'tcx> {
     }
 
     fn def_id(&mut self, did: DefId) {
-        // Hash the crate identification information.
-        let name = self.tcx.crate_name(did.krate);
-        let disambiguator = self.tcx.crate_disambiguator(did.krate);
-        self.hash((name, disambiguator));
-
-        // Hash the item path within that crate.
-        // FIXME(#35379) This should use a deterministic
-        // DefPath hashing mechanism, not the DefIndex.
-        self.hash(did.index);
+        // Hash the DefPath corresponding to the DefId, which is independent
+        // of compiler internal state.
+        let tcx = self.tcx;
+        let def_path = tcx.def_path(did);
+        def_path.deterministic_hash_to(tcx, &mut self.state);
     }
 }
 
@@ -445,33 +441,8 @@ impl<'a, 'gcx, 'tcx> TypeVisitor<'tcx> for TypeIdHasher<'a, 'gcx, 'tcx> {
                 self.hash(f.sig.variadic());
             }
             TyTrait(ref data) => {
-                // Trait objects have a list of projection bounds
-                // that are not guaranteed to be sorted in an order
-                // that gets preserved across crates, so we need
-                // to sort them again by the name, in string form.
-
-                // Hash the whole principal trait ref.
                 self.def_id(data.principal.def_id());
-                data.principal.visit_with(self);
-
-                // Hash region and builtin bounds.
-                data.region_bound.visit_with(self);
                 self.hash(data.builtin_bounds);
-
-                // Only projection bounds are left, sort and hash them.
-                let mut projection_bounds: Vec<_> = data.projection_bounds
-                                                        .iter()
-                                                        .map(|b| (b.item_name().as_str(), b))
-                                                        .collect();
-                projection_bounds.sort_by_key(|&(ref name, _)| name.clone());
-                for (name, bound) in projection_bounds {
-                    self.def_id(bound.0.trait_ref.def_id);
-                    self.hash(name);
-                    bound.visit_with(self);
-                }
-
-                // Bypass super_visit_with, we've visited everything.
-                return false;
             }
             TyTuple(tys) => {
                 self.hash(tys.len());