Rollup merge of rust-lang#65181 - nikomatsakis:lazy-norm-anon-const-p…

…ush-1, r=varkor

fix bug in folding for constants

These was a bug in the folding for constants that caused it to overlook bound regions. This branch includes some other little things that I did while trying to track the bug down.

r? @oli-obk

src/librustc/ty/flags.rs

@@ -250,7 +250,9 @@ impl FlagComputation {
             ConstValue::Placeholder(_) => {
                 self.add_flags(TypeFlags::HAS_FREE_REGIONS | TypeFlags::HAS_CT_PLACEHOLDER);
             }
-            _ => {},
+            ConstValue::Scalar(_) => { }
+            ConstValue::Slice { data: _, start: _, end: _ } => { }
+            ConstValue::ByRef { alloc: _, offset: _ } => { }
         }
     }
 

src/librustc/ty/fold.rs

@@ -911,13 +911,15 @@ impl<'tcx> TypeVisitor<'tcx> for HasEscapingVarsVisitor {
     }
 
     fn visit_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> bool {
-        if let ty::Const {
-            val: ConstValue::Infer(ty::InferConst::Canonical(debruijn, _)),
-            ..
-        } = *ct {
-            debruijn >= self.outer_index
-        } else {
-            false
+        // we don't have a `visit_infer_const` callback, so we have to
+        // hook in here to catch this case (annoying...), but
+        // otherwise we do want to remember to visit the rest of the
+        // const, as it has types/regions embedded in a lot of other
+        // places.
+        match ct.val {
+            ConstValue::Infer(ty::InferConst::Canonical(debruijn, _))
+                if debruijn >= self.outer_index => true,
+            _ => ct.super_visit_with(self),
         }
     }
 }

src/librustc/ty/print/pretty.rs

@@ -689,7 +689,7 @@ pub trait PrettyPrinter<'tcx>:
                 if self.tcx().sess.verbose() {
                     p!(write(
                         " closure_kind_ty={:?} closure_sig_ty={:?}",
-                        substs.as_closure().kind(did, self.tcx()),
+                        substs.as_closure().kind_ty(did, self.tcx()),
                         substs.as_closure().sig_ty(did, self.tcx())
                     ));
                 }
@@ -698,7 +698,9 @@ pub trait PrettyPrinter<'tcx>:
             },
             ty::Array(ty, sz) => {
                 p!(write("["), print(ty), write("; "));
-                if let ConstValue::Unevaluated(..) = sz.val {
+                if self.tcx().sess.verbose() {
+                    p!(write("{:?}", sz));
+                } else if let ConstValue::Unevaluated(..) = sz.val {
                     // do not try to evalute unevaluated constants. If we are const evaluating an
                     // array length anon const, rustc will (with debug assertions) print the
                     // constant's path. Which will end up here again.
@@ -855,6 +857,11 @@ pub trait PrettyPrinter<'tcx>:
     ) -> Result<Self::Const, Self::Error> {
         define_scoped_cx!(self);
 
+        if self.tcx().sess.verbose() {
+            p!(write("Const({:?}: {:?})", ct.val, ct.ty));
+            return Ok(self);
+        }
+
         let u8 = self.tcx().types.u8;
         if let ty::FnDef(did, substs) = ct.ty.kind {
             p!(print_value_path(did, substs));

src/librustc/ty/sty.rs

@@ -2203,7 +2203,9 @@ impl<'tcx> TyS<'tcx> {
                 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
             },
 
-            Infer(_) => None,
+            // "Bound" types appear in canonical queries when the
+            // closure type is not yet known
+            Bound(..) | Infer(_) => None,
 
             Error => Some(ty::ClosureKind::Fn),
 

src/librustc_traits/evaluate_obligation.rs

@@ -17,10 +17,12 @@ fn evaluate_obligation<'tcx>(
     tcx: TyCtxt<'tcx>,
     canonical_goal: CanonicalPredicateGoal<'tcx>,
 ) -> Result<EvaluationResult, OverflowError> {
+    debug!("evaluate_obligation(canonical_goal={:#?})", canonical_goal);
     tcx.infer_ctxt().enter_with_canonical(
         DUMMY_SP,
         &canonical_goal,
         |ref infcx, goal, _canonical_inference_vars| {
+            debug!("evaluate_obligation: goal={:#?}", goal);
             let ParamEnvAnd {
                 param_env,
                 value: predicate,