Auto merge of #47200 - BurntPizza:query-snatp, r=nikomatsakis

Make normalize_and_test_predicates into a query

From #44891.

I'm not real solid on how `dep_graph` stuff works, but if a node is going to have a key (again, not sure how important that is), then the key needs to be `Copy`. So since `normalize_and_test_predicates` only had one out-of-module use, I changed that call site to use a new function, `substitute_normalize_and_test_predicates` which is the query and enables having the arguments be `Copy`. Hopefully this makes sense.

r? @nikomatsakis
and/or @michaelwoerister

src/librustc/dep_graph/dep_node.rs

@@ -633,6 +633,8 @@ pub fn fingerprint_needed_for_crate_hash(self) -> bool {
     [anon] NormalizeTy,
     // We use this for most things when incr. comp. is turned off.
     [] Null,
+
+    [] SubstituteNormalizeAndTestPredicates { key: (DefId, &'tcx Substs<'tcx>) },
 );
 
 trait DepNodeParams<'a, 'gcx: 'tcx + 'a, 'tcx: 'a> : fmt::Debug {

src/librustc/traits/mod.rs

@@ -658,9 +658,9 @@ pub fn fully_normalize_with_fulfillcx<'a, 'gcx, 'tcx, T>(
 /// environment. If this returns false, then either normalize
 /// encountered an error or one of the predicates did not hold. Used
 /// when creating vtables to check for unsatisfiable methods.
-pub fn normalize_and_test_predicates<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                                               predicates: Vec<ty::Predicate<'tcx>>)
-                                               -> bool
+fn normalize_and_test_predicates<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
+                                           predicates: Vec<ty::Predicate<'tcx>>)
+                                           -> bool
 {
     debug!("normalize_and_test_predicates(predicates={:?})",
            predicates);
@@ -687,6 +687,22 @@ pub fn normalize_and_test_predicates<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     result
 }
 
+fn substitute_normalize_and_test_predicates<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
+                                                      key: (DefId, &'tcx Substs<'tcx>))
+                                                      -> bool
+{
+    use ty::subst::Subst;
+    debug!("substitute_normalize_and_test_predicates(key={:?})",
+           key);
+
+    let predicates = tcx.predicates_of(key.0).predicates.subst(tcx, key.1);
+    let result = normalize_and_test_predicates(tcx, predicates);
+
+    debug!("substitute_normalize_and_test_predicates(key={:?}) = {:?}",
+           key, result);
+    result
+}
+
 /// Given a trait `trait_ref`, iterates the vtable entries
 /// that come from `trait_ref`, including its supertraits.
 #[inline] // FIXME(#35870) Avoid closures being unexported due to impl Trait.
@@ -879,6 +895,7 @@ pub fn provide(providers: &mut ty::maps::Providers) {
         specializes: specialize::specializes,
         trans_fulfill_obligation: trans::trans_fulfill_obligation,
         vtable_methods,
+        substitute_normalize_and_test_predicates,
         ..*providers
     };
 }

src/librustc/ty/maps/config.rs

@@ -625,6 +625,12 @@ fn try_load_from_disk<'a>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     }
 }
 
+impl<'tcx> QueryDescription<'tcx> for queries::substitute_normalize_and_test_predicates<'tcx> {
+    fn describe(tcx: TyCtxt, key: (DefId, &'tcx Substs<'tcx>)) -> String {
+        format!("testing substituted normalized predicates:`{}`", tcx.item_path_str(key.0))
+    }
+}
+
 macro_rules! impl_disk_cacheable_query(
     ($query_name:ident, |$key:tt| $cond:expr) => {
         impl<'tcx> QueryDescription<'tcx> for queries::$query_name<'tcx> {

src/librustc/ty/maps/mod.rs

@@ -360,6 +360,9 @@
     // however, which uses this query as a kind of cache.
     [] fn erase_regions_ty: erase_regions_ty(Ty<'tcx>) -> Ty<'tcx>,
     [] fn fully_normalize_monormophic_ty: normalize_ty_node(Ty<'tcx>) -> Ty<'tcx>,
+
+    [] fn substitute_normalize_and_test_predicates:
+        substitute_normalize_and_test_predicates_node((DefId, &'tcx Substs<'tcx>)) -> bool,
 }
 
 //////////////////////////////////////////////////////////////////////
@@ -500,3 +503,8 @@ fn vtable_methods_node<'tcx>(trait_ref: ty::PolyTraitRef<'tcx>) -> DepConstructo
 fn normalize_ty_node<'tcx>(_: Ty<'tcx>) -> DepConstructor<'tcx> {
     DepConstructor::NormalizeTy
 }
+
+fn substitute_normalize_and_test_predicates_node<'tcx>(key: (DefId, &'tcx Substs<'tcx>))
+                                            -> DepConstructor<'tcx> {
+    DepConstructor::SubstituteNormalizeAndTestPredicates { key }
+}

src/librustc/ty/maps/plumbing.rs

@@ -760,6 +760,7 @@ pub fn force_from_dep_node<'a, 'gcx, 'lcx>(tcx: TyCtxt<'a, 'gcx, 'lcx>,
         DepKind::VtableMethods |
         DepKind::EraseRegionsTy |
         DepKind::NormalizeTy |
+        DepKind::SubstituteNormalizeAndTestPredicates |
 
         // This one should never occur in this context
         DepKind::Null => {

src/librustc_mir/monomorphize/item.rs

@@ -18,9 +18,8 @@
 use rustc::hir;
 use rustc::hir::def_id::DefId;
 use rustc::session::config::OptLevel;
-use rustc::traits;
 use rustc::ty::{self, Ty, TyCtxt};
-use rustc::ty::subst::{Subst, Substs};
+use rustc::ty::subst::Substs;
 use syntax::ast;
 use syntax::attr::{self, InlineAttr};
 use std::fmt::{self, Write};
@@ -214,8 +213,7 @@ fn is_instantiable(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> bool {
             MonoItem::GlobalAsm(..) => return true
         };
 
-        let predicates = tcx.predicates_of(def_id).predicates.subst(tcx, substs);
-        traits::normalize_and_test_predicates(tcx, predicates)
+        tcx.substitute_normalize_and_test_predicates((def_id, &substs))
     }
 
     fn to_string(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> String {