introduce a `NiceRegionError` type and define methods on that

This is more convenient, and allows us to be more independent from
infcx, particularly with respect to `in_progress_tables` field.

No functional change.

6 files changed, 137 insertions, 82 deletions

diff --git a/src/librustc/infer/error_reporting/mod.rs b/src/librustc/infer/error_reporting/mod.rs
index 224f2a3f8c9..aabe4057685 100644
--- a/src/librustc/infer/error_reporting/mod.rs
+++ b/src/librustc/infer/error_reporting/mod.rs
@@ -291,9 +291,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
         for error in errors {
             debug!("report_region_errors: error = {:?}", error);
 
-            if !self.try_report_named_anon_conflict(&error) &&
-                !self.try_report_anon_anon_conflict(&error)
-            {
+            if !self.try_report_nice_region_error(&error) {
                 match error.clone() {
                     // These errors could indicate all manner of different
                     // problems with many different solutions. Rather
diff --git a/src/librustc/infer/error_reporting/nice_region_error/different_lifetimes.rs b/src/librustc/infer/error_reporting/nice_region_error/different_lifetimes.rs
index 35c94853b9e..5061a2ba277 100644
--- a/src/librustc/infer/error_reporting/nice_region_error/different_lifetimes.rs
+++ b/src/librustc/infer/error_reporting/nice_region_error/different_lifetimes.rs
@@ -10,12 +10,10 @@
 
 //! Error Reporting for Anonymous Region Lifetime Errors
 //! where both the regions are anonymous.
-use infer::InferCtxt;
-use infer::lexical_region_resolve::RegionResolutionError::*;
-use infer::lexical_region_resolve::RegionResolutionError;
+use infer::error_reporting::nice_region_error::NiceRegionError;
 use infer::error_reporting::nice_region_error::util::AnonymousArgInfo;
 
-impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
+impl<'a, 'gcx, 'tcx> NiceRegionError<'a, 'gcx, 'tcx> {
     /// Print the error message for lifetime errors when both the concerned regions are anonymous.
     ///
     /// Consider a case where we have
@@ -52,12 +50,8 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
     /// ````
     ///
     /// It will later be extended to trait objects.
-    pub fn try_report_anon_anon_conflict(&self, error: &RegionResolutionError<'tcx>) -> bool {
-        let (span, sub, sup) = match *error {
-            ConcreteFailure(ref origin, sub, sup) => (origin.span(), sub, sup),
-            SubSupConflict(_, ref origin, sub, _, sup) => (origin.span(), sub, sup),
-            _ => return false, // inapplicable
-        };
+    pub(super) fn try_report_anon_anon_conflict(&self) -> bool {
+        let NiceRegionError { span, sub, sup, .. } = *self;
 
         // Determine whether the sub and sup consist of both anonymous (elided) regions.
         let anon_reg_sup = or_false!(self.is_suitable_region(sup));
diff --git a/src/librustc/infer/error_reporting/nice_region_error/find_anon_type.rs b/src/librustc/infer/error_reporting/nice_region_error/find_anon_type.rs
index 92fdb52e02f..dc53c1db06f 100644
--- a/src/librustc/infer/error_reporting/nice_region_error/find_anon_type.rs
+++ b/src/librustc/infer/error_reporting/nice_region_error/find_anon_type.rs
@@ -9,13 +9,13 @@
 // except according to those terms.
 
 use hir;
-use infer::InferCtxt;
-use ty::{self, Region};
+use ty::{self, Region, TyCtxt};
 use hir::map as hir_map;
 use middle::resolve_lifetime as rl;
 use hir::intravisit::{self, NestedVisitorMap, Visitor};
+use infer::error_reporting::nice_region_error::NiceRegionError;
 
-impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
+impl<'a, 'gcx, 'tcx> NiceRegionError<'a, 'gcx, 'tcx> {
     /// This function calls the `visit_ty` method for the parameters
     /// corresponding to the anonymous regions. The `nested_visitor.found_type`
     /// contains the anonymous type.
@@ -74,8 +74,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
         br: &ty::BoundRegion,
     ) -> Option<(&'gcx hir::Ty)> {
         let mut nested_visitor = FindNestedTypeVisitor {
-            infcx: &self,
-            hir_map: &self.tcx.hir,
+            tcx: self.tcx,
             bound_region: *br,
             found_type: None,
             depth: 1,
@@ -93,8 +92,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
 // where that lifetime appears. This allows us to highlight the
 // specific part of the type in the error message.
 struct FindNestedTypeVisitor<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
-    infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
-    hir_map: &'a hir::map::Map<'gcx>,
+    tcx: TyCtxt<'a, 'gcx, 'tcx>,
     // The bound_region corresponding to the Refree(freeregion)
     // associated with the anonymous region we are looking for.
     bound_region: ty::BoundRegion,
@@ -106,7 +104,7 @@ struct FindNestedTypeVisitor<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
 
 impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindNestedTypeVisitor<'a, 'gcx, 'tcx> {
     fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'gcx> {
-        NestedVisitorMap::OnlyBodies(&self.hir_map)
+        NestedVisitorMap::OnlyBodies(&self.tcx.hir)
     }
 
     fn visit_ty(&mut self, arg: &'gcx hir::Ty) {
@@ -126,8 +124,8 @@ impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindNestedTypeVisitor<'a, 'gcx, 'tcx> {
 
             hir::TyRptr(ref lifetime, _) => {
                 // the lifetime of the TyRptr
-                let hir_id = self.infcx.tcx.hir.node_to_hir_id(lifetime.id);
-                match (self.infcx.tcx.named_region(hir_id), self.bound_region) {
+                let hir_id = self.tcx.hir.node_to_hir_id(lifetime.id);
+                match (self.tcx.named_region(hir_id), self.bound_region) {
                     // Find the index of the anonymous region that was part of the
                     // error. We will then search the function parameters for a bound
                     // region at the right depth with the same index
@@ -195,10 +193,9 @@ impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindNestedTypeVisitor<'a, 'gcx, 'tcx> {
             // Checks if it is of type `hir::TyPath` which corresponds to a struct.
             hir::TyPath(_) => {
                 let subvisitor = &mut TyPathVisitor {
-                    infcx: self.infcx,
+                    tcx: self.tcx,
                     found_it: false,
                     bound_region: self.bound_region,
-                    hir_map: self.hir_map,
                     depth: self.depth,
                 };
                 intravisit::walk_ty(subvisitor, arg); // call walk_ty; as visit_ty is empty,
@@ -222,8 +219,7 @@ impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindNestedTypeVisitor<'a, 'gcx, 'tcx> {
 // where that lifetime appears. This allows us to highlight the
 // specific part of the type in the error message.
 struct TyPathVisitor<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
-    infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
-    hir_map: &'a hir::map::Map<'gcx>,
+    tcx: TyCtxt<'a, 'gcx, 'tcx>,
     found_it: bool,
     bound_region: ty::BoundRegion,
     depth: u32,
@@ -231,12 +227,12 @@ struct TyPathVisitor<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
 
 impl<'a, 'gcx, 'tcx> Visitor<'gcx> for TyPathVisitor<'a, 'gcx, 'tcx> {
     fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'gcx> {
-        NestedVisitorMap::OnlyBodies(&self.hir_map)
+        NestedVisitorMap::OnlyBodies(&self.tcx.hir)
     }
 
     fn visit_lifetime(&mut self, lifetime: &hir::Lifetime) {
-        let hir_id = self.infcx.tcx.hir.node_to_hir_id(lifetime.id);
-        match (self.infcx.tcx.named_region(hir_id), self.bound_region) {
+        let hir_id = self.tcx.hir.node_to_hir_id(lifetime.id);
+        match (self.tcx.named_region(hir_id), self.bound_region) {
             // the lifetime of the TyPath!
             (Some(rl::Region::LateBoundAnon(debruijn_index, anon_index)), ty::BrAnon(br_index)) => {
                 if debruijn_index.depth == self.depth && anon_index == br_index {
diff --git a/src/librustc/infer/error_reporting/nice_region_error/mod.rs b/src/librustc/infer/error_reporting/nice_region_error/mod.rs
index ca6247defe0..46283041fac 100644
--- a/src/librustc/infer/error_reporting/nice_region_error/mod.rs
+++ b/src/librustc/infer/error_reporting/nice_region_error/mod.rs
@@ -8,8 +8,56 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#[macro_use] mod util;
+use infer::InferCtxt;
+use infer::lexical_region_resolve::RegionResolutionError;
+use infer::lexical_region_resolve::RegionResolutionError::*;
+use syntax::codemap::Span;
+use ty::{self, TyCtxt};
+
+#[macro_use]
+mod util;
 
 mod find_anon_type;
 mod different_lifetimes;
 mod named_anon_conflict;
+
+impl<'cx, 'gcx, 'tcx> InferCtxt<'cx, 'gcx, 'tcx> {
+    pub fn try_report_nice_region_error(&self, error: &RegionResolutionError<'tcx>) -> bool {
+        let (span, sub, sup) = match *error {
+            ConcreteFailure(ref origin, sub, sup) => (origin.span(), sub, sup),
+            SubSupConflict(_, ref origin, sub, _, sup) => (origin.span(), sub, sup),
+            _ => return false, // inapplicable
+        };
+
+        if let Some(tables) = self.in_progress_tables {
+            let tables = tables.borrow();
+            NiceRegionError::new(self.tcx, span, sub, sup, Some(&tables)).try_report()
+        } else {
+            NiceRegionError::new(self.tcx, span, sub, sup, None).try_report()
+        }
+    }
+}
+
+pub struct NiceRegionError<'cx, 'gcx: 'tcx, 'tcx: 'cx> {
+    tcx: TyCtxt<'cx, 'gcx, 'tcx>,
+    span: Span,
+    sub: ty::Region<'tcx>,
+    sup: ty::Region<'tcx>,
+    tables: Option<&'cx ty::TypeckTables<'tcx>>,
+}
+
+impl<'cx, 'gcx, 'tcx> NiceRegionError<'cx, 'gcx, 'tcx> {
+    pub fn new(
+        tcx: TyCtxt<'cx, 'gcx, 'tcx>,
+        span: Span,
+        sub: ty::Region<'tcx>,
+        sup: ty::Region<'tcx>,
+        tables: Option<&'cx ty::TypeckTables<'tcx>>,
+    ) -> Self {
+        Self { tcx, span, sub, sup, tables }
+    }
+
+    pub fn try_report(&self) -> bool {
+        self.try_report_anon_anon_conflict() || self.try_report_named_anon_conflict()
+    }
+}
diff --git a/src/librustc/infer/error_reporting/nice_region_error/named_anon_conflict.rs b/src/librustc/infer/error_reporting/nice_region_error/named_anon_conflict.rs
index 6af7415ba53..87c3da2ee16 100644
--- a/src/librustc/infer/error_reporting/nice_region_error/named_anon_conflict.rs
+++ b/src/librustc/infer/error_reporting/nice_region_error/named_anon_conflict.rs
@@ -10,22 +10,20 @@
 
 //! Error Reporting for Anonymous Region Lifetime Errors
 //! where one region is named and the other is anonymous.
-use infer::InferCtxt;
-use infer::lexical_region_resolve::RegionResolutionError::*;
-use infer::lexical_region_resolve::RegionResolutionError;
+use infer::error_reporting::nice_region_error::NiceRegionError;
 use ty;
 
-impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
+impl<'a, 'gcx, 'tcx> NiceRegionError<'a, 'gcx, 'tcx> {
     /// When given a `ConcreteFailure` for a function with arguments containing a named region and
     /// an anonymous region, emit an descriptive diagnostic error.
-    pub fn try_report_named_anon_conflict(&self, error: &RegionResolutionError<'tcx>) -> bool {
-        let (span, sub, sup) = match *error {
-            ConcreteFailure(ref origin, sub, sup) => (origin.span(), sub, sup),
-            SubSupConflict(_, ref origin, sub, _, sup) => (origin.span(), sub, sup),
-            _ => return false, // inapplicable
-        };
+    pub(super) fn try_report_named_anon_conflict(&self) -> bool {
+        let NiceRegionError { span, sub, sup, .. } = *self;
 
-        debug!("try_report_named_anon_conflict(sub={:?}, sup={:?})", sub, sup);
+        debug!(
+            "try_report_named_anon_conflict(sub={:?}, sup={:?})",
+            sub,
+            sup
+        );
 
         // Determine whether the sub and sup consist of one named region ('a)
         // and one anonymous (elided) region. If so, find the parameter arg
@@ -33,33 +31,47 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
         // only introduced anonymous regions in parameters) as well as a
         // version new_ty of its type where the anonymous region is replaced
         // with the named one.//scope_def_id
-        let (named, anon, anon_arg_info, region_info) =
-            if self.is_named_region(sub) && self.is_suitable_region(sup).is_some() &&
-               self.find_arg_with_region(sup, sub).is_some() {
-                (sub,
-                 sup,
-                 self.find_arg_with_region(sup, sub).unwrap(),
-                 self.is_suitable_region(sup).unwrap())
-            } else if self.is_named_region(sup) && self.is_suitable_region(sub).is_some() &&
-                      self.find_arg_with_region(sub, sup).is_some() {
-                (sup,
-                 sub,
-                 self.find_arg_with_region(sub, sup).unwrap(),
-                 self.is_suitable_region(sub).unwrap())
-            } else {
-                return false; // inapplicable
-            };
+        let (named, anon, anon_arg_info, region_info) = if self.is_named_region(sub)
+            && self.is_suitable_region(sup).is_some()
+            && self.find_arg_with_region(sup, sub).is_some()
+        {
+            (
+                sub,
+                sup,
+                self.find_arg_with_region(sup, sub).unwrap(),
+                self.is_suitable_region(sup).unwrap(),
+            )
+        } else if self.is_named_region(sup) && self.is_suitable_region(sub).is_some()
+            && self.find_arg_with_region(sub, sup).is_some()
+        {
+            (
+                sup,
+                sub,
+                self.find_arg_with_region(sub, sup).unwrap(),
+                self.is_suitable_region(sub).unwrap(),
+            )
+        } else {
+            return false; // inapplicable
+        };
 
         debug!("try_report_named_anon_conflict: named = {:?}", named);
-        debug!("try_report_named_anon_conflict: anon_arg_info = {:?}", anon_arg_info);
-        debug!("try_report_named_anon_conflict: region_info = {:?}", region_info);
+        debug!(
+            "try_report_named_anon_conflict: anon_arg_info = {:?}",
+            anon_arg_info
+        );
+        debug!(
+            "try_report_named_anon_conflict: region_info = {:?}",
+            region_info
+        );
 
-        let (arg, new_ty, br, is_first, scope_def_id, is_impl_item) = (anon_arg_info.arg,
-                                                                       anon_arg_info.arg_ty,
-                                                                       anon_arg_info.bound_region,
-                                                                       anon_arg_info.is_first,
-                                                                       region_info.def_id,
-                                                                       region_info.is_impl_item);
+        let (arg, new_ty, br, is_first, scope_def_id, is_impl_item) = (
+            anon_arg_info.arg,
+            anon_arg_info.arg_ty,
+            anon_arg_info.bound_region,
+            anon_arg_info.is_first,
+            region_info.def_id,
+            region_info.is_impl_item,
+        );
         match br {
             ty::BrAnon(_) => {}
             _ => {
@@ -75,27 +87,34 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
         }
 
         if let Some((_, fndecl)) = self.find_anon_type(anon, &br) {
-            if self.is_return_type_anon(scope_def_id, br, fndecl).is_some() ||
-               self.is_self_anon(is_first, scope_def_id) {
+            if self.is_return_type_anon(scope_def_id, br, fndecl).is_some()
+                || self.is_self_anon(is_first, scope_def_id)
+            {
                 return false;
             }
         }
 
         let (error_var, span_label_var) = if let Some(simple_name) = arg.pat.simple_name() {
-            (format!("the type of `{}`", simple_name), format!("the type of `{}`", simple_name))
+            (
+                format!("the type of `{}`", simple_name),
+                format!("the type of `{}`", simple_name),
+            )
         } else {
             ("parameter type".to_owned(), "type".to_owned())
         };
 
-        struct_span_err!(self.tcx.sess,
-                         span,
-                         E0621,
-                         "explicit lifetime required in {}",
-                         error_var)
-                .span_label(arg.pat.span,
-                            format!("consider changing {} to `{}`", span_label_var, new_ty))
-                .span_label(span, format!("lifetime `{}` required", named))
-                .emit();
+        struct_span_err!(
+            self.tcx.sess,
+            span,
+            E0621,
+            "explicit lifetime required in {}",
+            error_var
+        ).span_label(
+            arg.pat.span,
+            format!("consider changing {} to `{}`", span_label_var, new_ty),
+        )
+            .span_label(span, format!("lifetime `{}` required", named))
+            .emit();
         return true;
     }
 }
diff --git a/src/librustc/infer/error_reporting/nice_region_error/util.rs b/src/librustc/infer/error_reporting/nice_region_error/util.rs
index 04584f34a15..9a9b8fbbb94 100644
--- a/src/librustc/infer/error_reporting/nice_region_error/util.rs
+++ b/src/librustc/infer/error_reporting/nice_region_error/util.rs
@@ -11,7 +11,7 @@
 //! Helper functions corresponding to lifetime errors due to
 //! anonymous regions.
 use hir;
-use infer::InferCtxt;
+use infer::error_reporting::nice_region_error::NiceRegionError;
 use ty::{self, Region, Ty};
 use hir::def_id::DefId;
 use hir::map as hir_map;
@@ -56,7 +56,7 @@ pub(super) struct FreeRegionInfo {
     pub is_impl_item: bool,
 }
 
-impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
+impl<'a, 'gcx, 'tcx> NiceRegionError<'a, 'gcx, 'tcx> {
     // This method walks the Type of the function body arguments using
     // `fold_regions()` function and returns the
     // &hir::Arg of the function argument corresponding to the anonymous
@@ -86,13 +86,13 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
         if let Some(node_id) = hir.as_local_node_id(id) {
             if let Some(body_id) = hir.maybe_body_owned_by(node_id) {
                 let body = hir.body(body_id);
-                if let Some(tables) = self.in_progress_tables {
+                if let Some(tables) = self.tables {
                     body.arguments
                         .iter()
                         .enumerate()
                         .filter_map(|(index, arg)| {
                             // May return None; sometimes the tables are not yet populated.
-                            let ty = tables.borrow().node_id_to_type_opt(arg.hir_id)?;
+                            let ty = tables.node_id_to_type_opt(arg.hir_id)?;
                             let mut found_anon_region = false;
                             let new_arg_ty = self.tcx.fold_regions(&ty, &mut false, |r, _| {
                                 if *r == *anon_region {