From 2f50c33290c81a548ea3237447cef0d1dbdc1a61 Mon Sep 17 00:00:00 2001
From: gaurikholkar <f2013002@goa.bits-pilani.ac.in>
Date: Sun, 6 Aug 2017 04:09:43 +0530
Subject: [PATCH 1/8] Adding E0623 for structs

---
 .../error_reporting/anon_anon_conflict.rs     | 326 ++++++++++++++++++
 .../error_reporting/different_lifetimes.rs    |   7 +
 .../ex3-both-anon-regions-4.stderr            |  18 +
 ...x3-both-anon-regions-both-are-structs-4.rs |  19 +
 ...oth-anon-regions-both-are-structs-4.stderr |  12 +
 .../ex3-both-anon-regions-one-is-struct-3.rs  |   4 +
 .../ex3-both-anon-regions-one-is-struct-4.rs  |  17 +
 ...3-both-anon-regions-one-is-struct-4.stderr |  10 +
 8 files changed, 413 insertions(+)
 create mode 100644 src/librustc/infer/error_reporting/anon_anon_conflict.rs
 create mode 100644 src/test/ui/lifetime-errors/ex3-both-anon-regions-4.stderr
 create mode 100644 src/test/ui/lifetime-errors/ex3-both-anon-regions-both-are-structs-4.rs
 create mode 100644 src/test/ui/lifetime-errors/ex3-both-anon-regions-both-are-structs-4.stderr
 create mode 100644 src/test/ui/lifetime-errors/ex3-both-anon-regions-one-is-struct-4.rs
 create mode 100644 src/test/ui/lifetime-errors/ex3-both-anon-regions-one-is-struct-4.stderr

diff --git a/src/librustc/infer/error_reporting/anon_anon_conflict.rs b/src/librustc/infer/error_reporting/anon_anon_conflict.rs
new file mode 100644
index 00000000000..c86bc71d310
--- /dev/null
+++ b/src/librustc/infer/error_reporting/anon_anon_conflict.rs
@@ -0,0 +1,326 @@
+// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Error Reporting for Anonymous Region Lifetime Errors
+//! where both the regions are anonymous.
+use hir;
+use infer::InferCtxt;
+use ty::{self, Region};
+use infer::region_inference::RegionResolutionError::*;
+use infer::region_inference::RegionResolutionError;
+use hir::map as hir_map;
+use middle::resolve_lifetime as rl;
+use hir::intravisit::{self, Visitor, NestedVisitorMap};
+
+impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
+    // This method prints the error message for lifetime errors when both the concerned regions
+    // are anonymous.
+    // Consider a case where we have
+    // fn foo(x: &mut Vec<&u8>, y: &u8)
+    //    { x.push(y); }.
+    // The example gives
+    // fn foo(x: &mut Vec<&u8>, y: &u8) {
+    //                    ---      --- these references are declared with different lifetimes...
+    //            x.push(y);
+    //            ^ ...but data from `y` flows into `x` here
+    // It has been extended for the case of structs too.
+    // Consider the example
+    // struct Ref<'a> { x: &'a u32 }
+    // fn foo(mut x: Vec<Ref>, y: Ref) {
+    //                   ---      --- these structs are declared with different lifetimes...
+    //               x.push(y);
+    //               ^ ...but data from `y` flows into `x` here
+    // }
+    // 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),
+            _ => return false, // inapplicable
+        };
+
+        // Determine whether the sub and sup consist of both anonymous (elided) regions.
+        let (ty1, ty2, scope_def_id_1, scope_def_id_2, bregion1, bregion2) = if
+            self.is_suitable_anonymous_region(sup, true).is_some() &&
+            self.is_suitable_anonymous_region(sub, true).is_some() {
+            if let (Some(anon_reg1), Some(anon_reg2)) =
+                (self.is_suitable_anonymous_region(sup, true),
+                 self.is_suitable_anonymous_region(sub, true)) {
+                let ((def_id1, br1), (def_id2, br2)) = (anon_reg1, anon_reg2);
+                let found_arg1 = self.find_anon_type(sup, &br1);
+                let found_arg2 = self.find_anon_type(sub, &br2);
+                match (found_arg1, found_arg2) {
+                    (Some(anonarg_1), Some(anonarg_2)) => {
+                        (anonarg_1, anonarg_2, def_id1, def_id2, br1, br2)
+                    }
+                    _ => {
+                        return false;
+                    }
+                }
+
+            } else {
+                return false;
+            }
+        } else {
+            return false; //inapplicable
+        };
+
+        let (label1, label2) = if let (Some(sup_arg), Some(sub_arg)) =
+            (self.find_arg_with_anonymous_region(sup, sup),
+             self.find_arg_with_anonymous_region(sub, sub)) {
+
+            let ((anon_arg1, _, _, is_first1), (anon_arg2, _, _, is_first2)) = (sup_arg, sub_arg);
+            if self.is_self_anon(is_first1, scope_def_id_1) ||
+               self.is_self_anon(is_first2, scope_def_id_2) {
+                return false;
+            }
+
+            if self.is_return_type_anon(scope_def_id_1, bregion1) ||
+               self.is_return_type_anon(scope_def_id_2, bregion2) {
+                return false;
+            }
+
+
+
+
+            if anon_arg1 == anon_arg2 {
+                (format!(" with one lifetime"), format!(" into the other"))
+            } else {
+                let span_label_var1 = if let Some(simple_name) = anon_arg1.pat.simple_name() {
+                    format!(" from `{}`", simple_name)
+                } else {
+                    format!("")
+                };
+
+                let span_label_var2 = if let Some(simple_name) = anon_arg2.pat.simple_name() {
+                    format!(" into `{}`", simple_name)
+                } else {
+                    format!("")
+                };
+
+                (span_label_var1, span_label_var2)
+            }
+        } else {
+            return false;
+        };
+
+        struct_span_err!(self.tcx.sess, span, E0623, "lifetime mismatch")
+            .span_label(ty1.span,
+                        format!("these two types are declared with different lifetimes..."))
+            .span_label(ty2.span, format!(""))
+            .span_label(span, format!("...but data{} flows{} here", label1, label2))
+            .emit();
+        return true;
+
+    }
+
+    /// This function calls the `visit_ty` method for the parameters
+    /// corresponding to the anonymous regions. The `nested_visitor.found_type`
+    /// contains the anonymous type.
+    ///
+    /// # Arguments
+    ///
+    /// region - the anonymous region corresponding to the anon_anon conflict
+    /// br - the bound region corresponding to the above region which is of type `BrAnon(_)`
+    ///
+    /// # Example
+    /// ```
+    /// fn foo(x: &mut Vec<&u8>, y: &u8)
+    ///    { x.push(y); }
+    /// ```
+    /// The function returns the nested type corresponding to the anonymous region
+    /// for e.g. `&u8` and Vec<`&u8`.
+    pub fn find_anon_type(&self, region: Region<'tcx>, br: &ty::BoundRegion) -> Option<(&hir::Ty)> {
+        if let Some(anon_reg) = self.is_suitable_anonymous_region(region, true) {
+            let (def_id, _) = anon_reg;
+            if let Some(node_id) = self.tcx.hir.as_local_node_id(def_id) {
+                let ret_ty = self.tcx.type_of(def_id);
+                if let ty::TyFnDef(_, _) = ret_ty.sty {
+                    if let hir_map::NodeItem(it) = self.tcx.hir.get(node_id) {
+                        if let hir::ItemFn(ref fndecl, _, _, _, _, _) = it.node {
+                            return fndecl
+                                       .inputs
+                                       .iter()
+                                       .filter_map(|arg| {
+                                                       self.find_visitor_found_type(&**arg, br)
+                                                   })
+                                       .next();
+                        }
+                    } else if let hir_map::NodeTraitItem(it) = self.tcx.hir.get(node_id) {
+                        if let hir::TraitItemKind::Method(ref fndecl, _) = it.node {
+                            return fndecl
+                                       .decl
+                                       .inputs
+                                       .iter()
+                                       .filter_map(|arg| {
+                                                       self.find_visitor_found_type(&**arg, br)
+                                                   })
+                                       .next();
+                        }
+                    } else if let hir_map::NodeImplItem(it) = self.tcx.hir.get(node_id) {
+                        if let hir::ImplItemKind::Method(ref fndecl, _) = it.node {
+                            return fndecl
+                                       .decl
+                                       .inputs
+                                       .iter()
+                                       .filter_map(|arg| {
+                                                       self.find_visitor_found_type(&**arg, br)
+                                                   })
+                                       .next();
+                        }
+                    }
+                }
+            }
+        }
+        None
+    }
+
+    // This method creates a FindNestedTypeVisitor which returns the type corresponding
+    // to the anonymous region.
+    fn find_visitor_found_type(&self,
+                               arg: &'gcx hir::Ty,
+                               br: &ty::BoundRegion)
+                               -> Option<(&'gcx hir::Ty)> {
+        let mut nested_visitor = FindNestedTypeVisitor {
+            infcx: &self,
+            hir_map: &self.tcx.hir,
+            bound_region: *br,
+            found_type: None,
+        };
+        nested_visitor.visit_ty(arg);
+        nested_visitor.found_type
+    }
+}
+
+// The FindNestedTypeVisitor captures the corresponding `hir::Ty` of the
+// anonymous region. The example above would lead to a conflict between
+// the two anonymous lifetimes for &u8 in x and y respectively. This visitor
+// would be invoked twice, once for each lifetime, and would
+// walk the types like &mut Vec<&u8> and &u8 looking for the HIR
+// 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>,
+    // The bound_region corresponding to the Refree(freeregion)
+    // associated with the anonymous region we are looking for.
+    bound_region: ty::BoundRegion,
+    // The type where the anonymous lifetime appears
+    // for e.g. Vec<`&u8`> and <`&u8`>
+    found_type: Option<&'gcx hir::Ty>,
+}
+
+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)
+    }
+
+    fn visit_ty(&mut self, arg: &'gcx hir::Ty) {
+        // 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.
+        let br_index = match self.bound_region {
+            ty::BrAnon(index) => index,
+            _ => return,
+        };
+
+        match arg.node {
+            hir::TyRptr(ref lifetime, _) => {
+                match self.infcx.tcx.named_region_map.defs.get(&lifetime.id) {
+                    // the lifetime of the TyRptr
+                    Some(&rl::Region::LateBoundAnon(debuijn_index, anon_index)) => {
+                        if debuijn_index.depth == 1 && anon_index == br_index {
+                            self.found_type = Some(arg);
+                            return; // we can stop visiting now
+                        }
+                    }
+                    Some(&rl::Region::Static) |
+                    Some(&rl::Region::EarlyBound(_, _)) |
+                    Some(&rl::Region::LateBound(_, _)) |
+                    Some(&rl::Region::Free(_, _)) |
+                    None => {
+                        debug!("no arg found");
+                    }
+                }
+            }
+            // Checks if it is of type `hir::TyPath` which corresponds to a struct.
+            hir::TyPath(_) => {
+                let subvisitor = &mut TyPathVisitor {
+                                          infcx: self.infcx,
+                                          found_it: false,
+                                          bound_region: self.bound_region,
+                                          hir_map: self.hir_map,
+                                      };
+                intravisit::walk_ty(subvisitor, arg); // call walk_ty; as visit_ty is empty,
+                // this will visit only outermost type
+                if subvisitor.found_it {
+                    self.found_type = Some(arg);
+                }
+            }
+            _ => {}
+        }
+        // walk the embedded contents: e.g., if we are visiting `Vec<&Foo>`,
+        // go on to visit `&Foo`
+        intravisit::walk_ty(self, arg);
+    }
+}
+
+// The visitor captures the corresponding `hir::Ty` of the anonymous region
+// in the case of structs ie. `hir::TyPath`.
+// This visitor would be invoked for each lifetime corresponding to a struct,
+// and would walk the types like Vec<Ref> in the above example and Ref looking for the HIR
+// 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>,
+    found_it: bool,
+    bound_region: ty::BoundRegion,
+}
+
+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)
+    }
+
+    fn visit_lifetime(&mut self, lifetime: &hir::Lifetime) {
+        let br_index = match self.bound_region {
+            ty::BrAnon(index) => index,
+            _ => return,
+        };
+
+
+        match self.infcx.tcx.named_region_map.defs.get(&lifetime.id) {
+            // the lifetime of the TyPath!
+            Some(&rl::Region::LateBoundAnon(debuijn_index, anon_index)) => {
+                if debuijn_index.depth == 1 && anon_index == br_index {
+                    self.found_it = true;
+                }
+            }
+            Some(&rl::Region::Static) |
+            Some(&rl::Region::EarlyBound(_, _)) |
+            Some(&rl::Region::LateBound(_, _)) |
+            Some(&rl::Region::Free(_, _)) |
+            None => {
+                debug!("no arg found");
+            }
+        }
+    }
+
+    fn visit_ty(&mut self, arg: &'gcx hir::Ty) {
+        // ignore nested types
+        //
+        // If you have a type like `Foo<'a, &Ty>` we
+        // are only interested in the immediate lifetimes ('a).
+        //
+        // Making `visit_ty` empty will ignore the `&Ty` embedded
+        // inside, it will get reached by the outer visitor.
+        debug!("`Ty` corresponding to a struct is {:?}", arg);
+    }
+}
diff --git a/src/librustc/infer/error_reporting/different_lifetimes.rs b/src/librustc/infer/error_reporting/different_lifetimes.rs
index 23f6d1a3fb0..9546d8a4dd2 100644
--- a/src/librustc/infer/error_reporting/different_lifetimes.rs
+++ b/src/librustc/infer/error_reporting/different_lifetimes.rs
@@ -204,6 +204,13 @@ impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindNestedTypeVisitor<'a, 'gcx, 'tcx> {
 
     fn visit_ty(&mut self, arg: &'gcx hir::Ty) {
         match arg.node {
+            hir::TyBareFn(_) => {
+                self.depth += 1;
+                intravisit::walk_ty(self, arg);
+                self.depth -= 1;
+                return;
+            }
+            
             hir::TyRptr(ref lifetime, _) => {
                 // the lifetime of the TyRptr
                 let hir_id = self.infcx.tcx.hir.node_to_hir_id(lifetime.id);
diff --git a/src/test/ui/lifetime-errors/ex3-both-anon-regions-4.stderr b/src/test/ui/lifetime-errors/ex3-both-anon-regions-4.stderr
new file mode 100644
index 00000000000..b159e147869
--- /dev/null
+++ b/src/test/ui/lifetime-errors/ex3-both-anon-regions-4.stderr
@@ -0,0 +1,18 @@
+error[E0623]: lifetime mismatch
+  --> $DIR/ex3-both-anon-regions-4.rs:12:13
+   |
+11 | fn foo(z: &mut Vec<(&u8,&u8)>, (x, y): (&u8, &u8)) {
+   |                     ---                 --- these references are declared with different lifetimes...
+12 |     z.push((x,y));
+   |             ^ ...but data flows into `z` here
+
+error[E0623]: lifetime mismatch
+  --> $DIR/ex3-both-anon-regions-4.rs:12:15
+   |
+11 | fn foo(z: &mut Vec<(&u8,&u8)>, (x, y): (&u8, &u8)) {
+   |                         ---                  --- these references are declared with different lifetimes...
+12 |     z.push((x,y));
+   |               ^ ...but data flows into `z` here
+
+error: aborting due to 2 previous errors
+
diff --git a/src/test/ui/lifetime-errors/ex3-both-anon-regions-both-are-structs-4.rs b/src/test/ui/lifetime-errors/ex3-both-anon-regions-both-are-structs-4.rs
new file mode 100644
index 00000000000..606e611865f
--- /dev/null
+++ b/src/test/ui/lifetime-errors/ex3-both-anon-regions-both-are-structs-4.rs
@@ -0,0 +1,19 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+struct Ref<'a, 'b> {
+    a: &'a u32,
+    b: &'b u32,
+}
+
+fn foo(mut x: Ref) {
+    x.a = x.b;
+}
+
+fn main() {}
diff --git a/src/test/ui/lifetime-errors/ex3-both-anon-regions-both-are-structs-4.stderr b/src/test/ui/lifetime-errors/ex3-both-anon-regions-both-are-structs-4.stderr
new file mode 100644
index 00000000000..2ef1cd507f1
--- /dev/null
+++ b/src/test/ui/lifetime-errors/ex3-both-anon-regions-both-are-structs-4.stderr
@@ -0,0 +1,12 @@
+error[E0623]: lifetime mismatch
+  --> $DIR/ex3-both-anon-regions-both-are-structs-4.rs:16:11
+   |
+15 | fn foo(mut x: Ref) {
+   |               ---
+   |               |
+   |               these two types are declared with different lifetimes...
+16 |     x.a = x.b;
+   |           ^^^ ...but data with one lifetime flows into the other here
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/lifetime-errors/ex3-both-anon-regions-one-is-struct-3.rs b/src/test/ui/lifetime-errors/ex3-both-anon-regions-one-is-struct-3.rs
index 4933dbb7e7a..5920eeed6b1 100644
--- a/src/test/ui/lifetime-errors/ex3-both-anon-regions-one-is-struct-3.rs
+++ b/src/test/ui/lifetime-errors/ex3-both-anon-regions-one-is-struct-3.rs
@@ -11,7 +11,11 @@
 struct Ref<'a, 'b> { a: &'a u32, b: &'b u32 }
 
 fn foo(mut y: Ref, x: &u32) {
+<<<<<<< HEAD
     y.b = x;
+=======
+    x = y.b;
+>>>>>>> Adding E0623 for structs
 }
 
 fn main() { }
diff --git a/src/test/ui/lifetime-errors/ex3-both-anon-regions-one-is-struct-4.rs b/src/test/ui/lifetime-errors/ex3-both-anon-regions-one-is-struct-4.rs
new file mode 100644
index 00000000000..4933dbb7e7a
--- /dev/null
+++ b/src/test/ui/lifetime-errors/ex3-both-anon-regions-one-is-struct-4.rs
@@ -0,0 +1,17 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+struct Ref<'a, 'b> { a: &'a u32, b: &'b u32 }
+
+fn foo(mut y: Ref, x: &u32) {
+    y.b = x;
+}
+
+fn main() { }
diff --git a/src/test/ui/lifetime-errors/ex3-both-anon-regions-one-is-struct-4.stderr b/src/test/ui/lifetime-errors/ex3-both-anon-regions-one-is-struct-4.stderr
new file mode 100644
index 00000000000..40f026bcb1b
--- /dev/null
+++ b/src/test/ui/lifetime-errors/ex3-both-anon-regions-one-is-struct-4.stderr
@@ -0,0 +1,10 @@
+error[E0623]: lifetime mismatch
+  --> $DIR/ex3-both-anon-regions-one-is-struct-4.rs:14:11
+   |
+13 | fn foo(mut y: Ref, x: &u32) {
+   |               ---     ---- these two types are declared with different lifetimes...
+14 |     y.b = x;
+   |           ^ ...but data from `x` flows into `y` here
+
+error: aborting due to previous error
+

From ed1181272e5f33c2a329c3cf0e267cae99fab06a Mon Sep 17 00:00:00 2001
From: gaurikholkar <f2013002@goa.bits-pilani.ac.in>
Date: Tue, 15 Aug 2017 10:21:31 +0530
Subject: [PATCH 2/8] extend E0623 for fns

---
 .../error_reporting/anon_anon_conflict.rs     | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/src/librustc/infer/error_reporting/anon_anon_conflict.rs b/src/librustc/infer/error_reporting/anon_anon_conflict.rs
index c86bc71d310..bb4782d2c8f 100644
--- a/src/librustc/infer/error_reporting/anon_anon_conflict.rs
+++ b/src/librustc/infer/error_reporting/anon_anon_conflict.rs
@@ -192,6 +192,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             hir_map: &self.tcx.hir,
             bound_region: *br,
             found_type: None,
+            depth: 0,
         };
         nested_visitor.visit_ty(arg);
         nested_visitor.found_type
@@ -214,6 +215,7 @@ struct FindNestedTypeVisitor<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
     // The type where the anonymous lifetime appears
     // for e.g. Vec<`&u8`> and <`&u8`>
     found_type: Option<&'gcx hir::Ty>,
+    depth: u32,
 }
 
 impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindNestedTypeVisitor<'a, 'gcx, 'tcx> {
@@ -263,11 +265,35 @@ impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindNestedTypeVisitor<'a, 'gcx, 'tcx> {
                     self.found_type = Some(arg);
                 }
             }
+
+            hir::TyBareFn(ref fndecl) => {
+                fndecl.lifetimes.iter().filter_map(|lf| {
+                    match self.infcx.tcx.named_region_map.defs.get(&lf.lifetime.id) {
+
+                        Some(&rl::Region::LateBoundAnon(debuijn_index, anon_index)) => {
+                        if debuijn_index.depth == self.depth && anon_index == br_index {
+                            self.found_type = Some(arg);
+                            return; // we can stop visiting now
+                        }else{}
+                    }
+                    Some(&rl::Region::Static) |
+                    Some(&rl::Region::EarlyBound(_, _)) |
+                    Some(&rl::Region::LateBound(_, _)) |
+                    Some(&rl::Region::Free(_, _)) |
+                    None => {
+                        debug!("no arg found");
+                    }
+                }       
+            
+            }).next();}
+            
             _ => {}
         }
         // walk the embedded contents: e.g., if we are visiting `Vec<&Foo>`,
         // go on to visit `&Foo`
+        self.depth += 1;
         intravisit::walk_ty(self, arg);
+        self.depth += 1;
     }
 }
 

From b2d869dc8075a78d5f2f163f6691bad14b16e4b0 Mon Sep 17 00:00:00 2001
From: gaurikholkar <f2013002@goa.bits-pilani.ac.in>
Date: Tue, 15 Aug 2017 22:16:29 +0530
Subject: [PATCH 3/8] add logs

---
 fn.rs                                                  |  8 ++++++++
 .../infer/error_reporting/anon_anon_conflict.rs        | 10 +++++++---
 2 files changed, 15 insertions(+), 3 deletions(-)
 create mode 100644 fn.rs

diff --git a/fn.rs b/fn.rs
new file mode 100644
index 00000000000..186eda95fec
--- /dev/null
+++ b/fn.rs
@@ -0,0 +1,8 @@
+
+fn foo(x:  fn(&u8, &u8), y: Vec<&u8>, z: &u8) {
+// Debruijn   1    1            1        1
+// Anon-Index 0    1            0        1
+//            ------
+//            debruijn indices are shifted by 1 in here
+  y.push(z); // index will be zero or one
+}
diff --git a/src/librustc/infer/error_reporting/anon_anon_conflict.rs b/src/librustc/infer/error_reporting/anon_anon_conflict.rs
index bb4782d2c8f..634f5788660 100644
--- a/src/librustc/infer/error_reporting/anon_anon_conflict.rs
+++ b/src/librustc/infer/error_reporting/anon_anon_conflict.rs
@@ -267,14 +267,17 @@ impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindNestedTypeVisitor<'a, 'gcx, 'tcx> {
             }
 
             hir::TyBareFn(ref fndecl) => {
-                fndecl.lifetimes.iter().filter_map(|lf| {
+                fndecl.lifetimes.iter().map(|lf| {
+                                            debug!("arg we are handling is...{:?}",arg);
                     match self.infcx.tcx.named_region_map.defs.get(&lf.lifetime.id) {
-
                         Some(&rl::Region::LateBoundAnon(debuijn_index, anon_index)) => {
+                            debug!("debuijn_index.depth ={:?} self.depth = {:?} anon_index ={:?} br_index={:?}",
+                            debuijn_index.depth, self.depth, anon_index, br_index);
                         if debuijn_index.depth == self.depth && anon_index == br_index {
+                            debug!("arg is {:?}",Some(arg));
                             self.found_type = Some(arg);
                             return; // we can stop visiting now
-                        }else{}
+                        }
                     }
                     Some(&rl::Region::Static) |
                     Some(&rl::Region::EarlyBound(_, _)) |
@@ -292,6 +295,7 @@ impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindNestedTypeVisitor<'a, 'gcx, 'tcx> {
         // walk the embedded contents: e.g., if we are visiting `Vec<&Foo>`,
         // go on to visit `&Foo`
         self.depth += 1;
+        debug!("depth is {:?}",self.depth);
         intravisit::walk_ty(self, arg);
         self.depth += 1;
     }

From 54af57018b57810c4467b6ed092a0294c3467ef5 Mon Sep 17 00:00:00 2001
From: gaurikholkar <f2013002@goa.bits-pilani.ac.in>
Date: Mon, 11 Sep 2017 23:58:29 +0530
Subject: [PATCH 4/8] correct depth initialisation

---
 .../error_reporting/anon_anon_conflict.rs     | 40 +++++--------------
 1 file changed, 11 insertions(+), 29 deletions(-)

diff --git a/src/librustc/infer/error_reporting/anon_anon_conflict.rs b/src/librustc/infer/error_reporting/anon_anon_conflict.rs
index 634f5788660..420ac040b30 100644
--- a/src/librustc/infer/error_reporting/anon_anon_conflict.rs
+++ b/src/librustc/infer/error_reporting/anon_anon_conflict.rs
@@ -192,7 +192,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             hir_map: &self.tcx.hir,
             bound_region: *br,
             found_type: None,
-            depth: 0,
+            depth: 1,
         };
         nested_visitor.visit_ty(arg);
         nested_visitor.found_type
@@ -233,6 +233,14 @@ impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindNestedTypeVisitor<'a, 'gcx, 'tcx> {
         };
 
         match arg.node {
+
+            hir::TyBareFn(ref fndecl) => {
+                self.depth += 1;
+                intravisit::walk_ty(self, arg);
+                self.depth -= 1;
+                return;
+            }
+
             hir::TyRptr(ref lifetime, _) => {
                 match self.infcx.tcx.named_region_map.defs.get(&lifetime.id) {
                     // the lifetime of the TyRptr
@@ -266,38 +274,13 @@ impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindNestedTypeVisitor<'a, 'gcx, 'tcx> {
                 }
             }
 
-            hir::TyBareFn(ref fndecl) => {
-                fndecl.lifetimes.iter().map(|lf| {
-                                            debug!("arg we are handling is...{:?}",arg);
-                    match self.infcx.tcx.named_region_map.defs.get(&lf.lifetime.id) {
-                        Some(&rl::Region::LateBoundAnon(debuijn_index, anon_index)) => {
-                            debug!("debuijn_index.depth ={:?} self.depth = {:?} anon_index ={:?} br_index={:?}",
-                            debuijn_index.depth, self.depth, anon_index, br_index);
-                        if debuijn_index.depth == self.depth && anon_index == br_index {
-                            debug!("arg is {:?}",Some(arg));
-                            self.found_type = Some(arg);
-                            return; // we can stop visiting now
-                        }
-                    }
-                    Some(&rl::Region::Static) |
-                    Some(&rl::Region::EarlyBound(_, _)) |
-                    Some(&rl::Region::LateBound(_, _)) |
-                    Some(&rl::Region::Free(_, _)) |
-                    None => {
-                        debug!("no arg found");
-                    }
-                }       
-            
-            }).next();}
-            
             _ => {}
         }
         // walk the embedded contents: e.g., if we are visiting `Vec<&Foo>`,
         // go on to visit `&Foo`
-        self.depth += 1;
-        debug!("depth is {:?}",self.depth);
+        debug!("depth is {:?}", self.depth);
         intravisit::walk_ty(self, arg);
-        self.depth += 1;
+
     }
 }
 
@@ -325,7 +308,6 @@ impl<'a, 'gcx, 'tcx> Visitor<'gcx> for TyPathVisitor<'a, 'gcx, 'tcx> {
             _ => return,
         };
 
-
         match self.infcx.tcx.named_region_map.defs.get(&lifetime.id) {
             // the lifetime of the TyPath!
             Some(&rl::Region::LateBoundAnon(debuijn_index, anon_index)) => {

From a128051f87be0baa953adbedfe780c1ef35379b6 Mon Sep 17 00:00:00 2001
From: gaurikholkar <f2013002@goa.bits-pilani.ac.in>
Date: Tue, 12 Sep 2017 00:34:52 +0530
Subject: [PATCH 5/8] fixes

---
 .../error_reporting/anon_anon_conflict.rs     | 338 ------------------
 1 file changed, 338 deletions(-)
 delete mode 100644 src/librustc/infer/error_reporting/anon_anon_conflict.rs

diff --git a/src/librustc/infer/error_reporting/anon_anon_conflict.rs b/src/librustc/infer/error_reporting/anon_anon_conflict.rs
deleted file mode 100644
index 420ac040b30..00000000000
--- a/src/librustc/infer/error_reporting/anon_anon_conflict.rs
+++ /dev/null
@@ -1,338 +0,0 @@
-// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-//! Error Reporting for Anonymous Region Lifetime Errors
-//! where both the regions are anonymous.
-use hir;
-use infer::InferCtxt;
-use ty::{self, Region};
-use infer::region_inference::RegionResolutionError::*;
-use infer::region_inference::RegionResolutionError;
-use hir::map as hir_map;
-use middle::resolve_lifetime as rl;
-use hir::intravisit::{self, Visitor, NestedVisitorMap};
-
-impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
-    // This method prints the error message for lifetime errors when both the concerned regions
-    // are anonymous.
-    // Consider a case where we have
-    // fn foo(x: &mut Vec<&u8>, y: &u8)
-    //    { x.push(y); }.
-    // The example gives
-    // fn foo(x: &mut Vec<&u8>, y: &u8) {
-    //                    ---      --- these references are declared with different lifetimes...
-    //            x.push(y);
-    //            ^ ...but data from `y` flows into `x` here
-    // It has been extended for the case of structs too.
-    // Consider the example
-    // struct Ref<'a> { x: &'a u32 }
-    // fn foo(mut x: Vec<Ref>, y: Ref) {
-    //                   ---      --- these structs are declared with different lifetimes...
-    //               x.push(y);
-    //               ^ ...but data from `y` flows into `x` here
-    // }
-    // 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),
-            _ => return false, // inapplicable
-        };
-
-        // Determine whether the sub and sup consist of both anonymous (elided) regions.
-        let (ty1, ty2, scope_def_id_1, scope_def_id_2, bregion1, bregion2) = if
-            self.is_suitable_anonymous_region(sup, true).is_some() &&
-            self.is_suitable_anonymous_region(sub, true).is_some() {
-            if let (Some(anon_reg1), Some(anon_reg2)) =
-                (self.is_suitable_anonymous_region(sup, true),
-                 self.is_suitable_anonymous_region(sub, true)) {
-                let ((def_id1, br1), (def_id2, br2)) = (anon_reg1, anon_reg2);
-                let found_arg1 = self.find_anon_type(sup, &br1);
-                let found_arg2 = self.find_anon_type(sub, &br2);
-                match (found_arg1, found_arg2) {
-                    (Some(anonarg_1), Some(anonarg_2)) => {
-                        (anonarg_1, anonarg_2, def_id1, def_id2, br1, br2)
-                    }
-                    _ => {
-                        return false;
-                    }
-                }
-
-            } else {
-                return false;
-            }
-        } else {
-            return false; //inapplicable
-        };
-
-        let (label1, label2) = if let (Some(sup_arg), Some(sub_arg)) =
-            (self.find_arg_with_anonymous_region(sup, sup),
-             self.find_arg_with_anonymous_region(sub, sub)) {
-
-            let ((anon_arg1, _, _, is_first1), (anon_arg2, _, _, is_first2)) = (sup_arg, sub_arg);
-            if self.is_self_anon(is_first1, scope_def_id_1) ||
-               self.is_self_anon(is_first2, scope_def_id_2) {
-                return false;
-            }
-
-            if self.is_return_type_anon(scope_def_id_1, bregion1) ||
-               self.is_return_type_anon(scope_def_id_2, bregion2) {
-                return false;
-            }
-
-
-
-
-            if anon_arg1 == anon_arg2 {
-                (format!(" with one lifetime"), format!(" into the other"))
-            } else {
-                let span_label_var1 = if let Some(simple_name) = anon_arg1.pat.simple_name() {
-                    format!(" from `{}`", simple_name)
-                } else {
-                    format!("")
-                };
-
-                let span_label_var2 = if let Some(simple_name) = anon_arg2.pat.simple_name() {
-                    format!(" into `{}`", simple_name)
-                } else {
-                    format!("")
-                };
-
-                (span_label_var1, span_label_var2)
-            }
-        } else {
-            return false;
-        };
-
-        struct_span_err!(self.tcx.sess, span, E0623, "lifetime mismatch")
-            .span_label(ty1.span,
-                        format!("these two types are declared with different lifetimes..."))
-            .span_label(ty2.span, format!(""))
-            .span_label(span, format!("...but data{} flows{} here", label1, label2))
-            .emit();
-        return true;
-
-    }
-
-    /// This function calls the `visit_ty` method for the parameters
-    /// corresponding to the anonymous regions. The `nested_visitor.found_type`
-    /// contains the anonymous type.
-    ///
-    /// # Arguments
-    ///
-    /// region - the anonymous region corresponding to the anon_anon conflict
-    /// br - the bound region corresponding to the above region which is of type `BrAnon(_)`
-    ///
-    /// # Example
-    /// ```
-    /// fn foo(x: &mut Vec<&u8>, y: &u8)
-    ///    { x.push(y); }
-    /// ```
-    /// The function returns the nested type corresponding to the anonymous region
-    /// for e.g. `&u8` and Vec<`&u8`.
-    pub fn find_anon_type(&self, region: Region<'tcx>, br: &ty::BoundRegion) -> Option<(&hir::Ty)> {
-        if let Some(anon_reg) = self.is_suitable_anonymous_region(region, true) {
-            let (def_id, _) = anon_reg;
-            if let Some(node_id) = self.tcx.hir.as_local_node_id(def_id) {
-                let ret_ty = self.tcx.type_of(def_id);
-                if let ty::TyFnDef(_, _) = ret_ty.sty {
-                    if let hir_map::NodeItem(it) = self.tcx.hir.get(node_id) {
-                        if let hir::ItemFn(ref fndecl, _, _, _, _, _) = it.node {
-                            return fndecl
-                                       .inputs
-                                       .iter()
-                                       .filter_map(|arg| {
-                                                       self.find_visitor_found_type(&**arg, br)
-                                                   })
-                                       .next();
-                        }
-                    } else if let hir_map::NodeTraitItem(it) = self.tcx.hir.get(node_id) {
-                        if let hir::TraitItemKind::Method(ref fndecl, _) = it.node {
-                            return fndecl
-                                       .decl
-                                       .inputs
-                                       .iter()
-                                       .filter_map(|arg| {
-                                                       self.find_visitor_found_type(&**arg, br)
-                                                   })
-                                       .next();
-                        }
-                    } else if let hir_map::NodeImplItem(it) = self.tcx.hir.get(node_id) {
-                        if let hir::ImplItemKind::Method(ref fndecl, _) = it.node {
-                            return fndecl
-                                       .decl
-                                       .inputs
-                                       .iter()
-                                       .filter_map(|arg| {
-                                                       self.find_visitor_found_type(&**arg, br)
-                                                   })
-                                       .next();
-                        }
-                    }
-                }
-            }
-        }
-        None
-    }
-
-    // This method creates a FindNestedTypeVisitor which returns the type corresponding
-    // to the anonymous region.
-    fn find_visitor_found_type(&self,
-                               arg: &'gcx hir::Ty,
-                               br: &ty::BoundRegion)
-                               -> Option<(&'gcx hir::Ty)> {
-        let mut nested_visitor = FindNestedTypeVisitor {
-            infcx: &self,
-            hir_map: &self.tcx.hir,
-            bound_region: *br,
-            found_type: None,
-            depth: 1,
-        };
-        nested_visitor.visit_ty(arg);
-        nested_visitor.found_type
-    }
-}
-
-// The FindNestedTypeVisitor captures the corresponding `hir::Ty` of the
-// anonymous region. The example above would lead to a conflict between
-// the two anonymous lifetimes for &u8 in x and y respectively. This visitor
-// would be invoked twice, once for each lifetime, and would
-// walk the types like &mut Vec<&u8> and &u8 looking for the HIR
-// 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>,
-    // The bound_region corresponding to the Refree(freeregion)
-    // associated with the anonymous region we are looking for.
-    bound_region: ty::BoundRegion,
-    // The type where the anonymous lifetime appears
-    // for e.g. Vec<`&u8`> and <`&u8`>
-    found_type: Option<&'gcx hir::Ty>,
-    depth: u32,
-}
-
-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)
-    }
-
-    fn visit_ty(&mut self, arg: &'gcx hir::Ty) {
-        // 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.
-        let br_index = match self.bound_region {
-            ty::BrAnon(index) => index,
-            _ => return,
-        };
-
-        match arg.node {
-
-            hir::TyBareFn(ref fndecl) => {
-                self.depth += 1;
-                intravisit::walk_ty(self, arg);
-                self.depth -= 1;
-                return;
-            }
-
-            hir::TyRptr(ref lifetime, _) => {
-                match self.infcx.tcx.named_region_map.defs.get(&lifetime.id) {
-                    // the lifetime of the TyRptr
-                    Some(&rl::Region::LateBoundAnon(debuijn_index, anon_index)) => {
-                        if debuijn_index.depth == 1 && anon_index == br_index {
-                            self.found_type = Some(arg);
-                            return; // we can stop visiting now
-                        }
-                    }
-                    Some(&rl::Region::Static) |
-                    Some(&rl::Region::EarlyBound(_, _)) |
-                    Some(&rl::Region::LateBound(_, _)) |
-                    Some(&rl::Region::Free(_, _)) |
-                    None => {
-                        debug!("no arg found");
-                    }
-                }
-            }
-            // Checks if it is of type `hir::TyPath` which corresponds to a struct.
-            hir::TyPath(_) => {
-                let subvisitor = &mut TyPathVisitor {
-                                          infcx: self.infcx,
-                                          found_it: false,
-                                          bound_region: self.bound_region,
-                                          hir_map: self.hir_map,
-                                      };
-                intravisit::walk_ty(subvisitor, arg); // call walk_ty; as visit_ty is empty,
-                // this will visit only outermost type
-                if subvisitor.found_it {
-                    self.found_type = Some(arg);
-                }
-            }
-
-            _ => {}
-        }
-        // walk the embedded contents: e.g., if we are visiting `Vec<&Foo>`,
-        // go on to visit `&Foo`
-        debug!("depth is {:?}", self.depth);
-        intravisit::walk_ty(self, arg);
-
-    }
-}
-
-// The visitor captures the corresponding `hir::Ty` of the anonymous region
-// in the case of structs ie. `hir::TyPath`.
-// This visitor would be invoked for each lifetime corresponding to a struct,
-// and would walk the types like Vec<Ref> in the above example and Ref looking for the HIR
-// 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>,
-    found_it: bool,
-    bound_region: ty::BoundRegion,
-}
-
-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)
-    }
-
-    fn visit_lifetime(&mut self, lifetime: &hir::Lifetime) {
-        let br_index = match self.bound_region {
-            ty::BrAnon(index) => index,
-            _ => return,
-        };
-
-        match self.infcx.tcx.named_region_map.defs.get(&lifetime.id) {
-            // the lifetime of the TyPath!
-            Some(&rl::Region::LateBoundAnon(debuijn_index, anon_index)) => {
-                if debuijn_index.depth == 1 && anon_index == br_index {
-                    self.found_it = true;
-                }
-            }
-            Some(&rl::Region::Static) |
-            Some(&rl::Region::EarlyBound(_, _)) |
-            Some(&rl::Region::LateBound(_, _)) |
-            Some(&rl::Region::Free(_, _)) |
-            None => {
-                debug!("no arg found");
-            }
-        }
-    }
-
-    fn visit_ty(&mut self, arg: &'gcx hir::Ty) {
-        // ignore nested types
-        //
-        // If you have a type like `Foo<'a, &Ty>` we
-        // are only interested in the immediate lifetimes ('a).
-        //
-        // Making `visit_ty` empty will ignore the `&Ty` embedded
-        // inside, it will get reached by the outer visitor.
-        debug!("`Ty` corresponding to a struct is {:?}", arg);
-    }
-}

From 93529b40ca9471ebe3f79817d4f71a5245bec50e Mon Sep 17 00:00:00 2001
From: gaurikholkar <f2013002@goa.bits-pilani.ac.in>
Date: Tue, 12 Sep 2017 16:48:01 +0530
Subject: [PATCH 6/8] add ui test for fn items, tidy fixes

---
 .../infer/error_reporting/different_lifetimes.rs   |  2 +-
 .../ex3-both-anon-regions-one-is-struct-3.rs       |  4 ----
 .../ex3-both-anon-regions-using-fn-items.rs        | 14 ++++++++++++++
 .../ex3-both-anon-regions-using-fn-items.stderr    | 10 ++++++++++
 4 files changed, 25 insertions(+), 5 deletions(-)
 create mode 100644 src/test/ui/lifetime-errors/ex3-both-anon-regions-using-fn-items.rs
 create mode 100644 src/test/ui/lifetime-errors/ex3-both-anon-regions-using-fn-items.stderr

diff --git a/src/librustc/infer/error_reporting/different_lifetimes.rs b/src/librustc/infer/error_reporting/different_lifetimes.rs
index 9546d8a4dd2..a54e75857dd 100644
--- a/src/librustc/infer/error_reporting/different_lifetimes.rs
+++ b/src/librustc/infer/error_reporting/different_lifetimes.rs
@@ -210,7 +210,7 @@ impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindNestedTypeVisitor<'a, 'gcx, 'tcx> {
                 self.depth -= 1;
                 return;
             }
-            
+
             hir::TyRptr(ref lifetime, _) => {
                 // the lifetime of the TyRptr
                 let hir_id = self.infcx.tcx.hir.node_to_hir_id(lifetime.id);
diff --git a/src/test/ui/lifetime-errors/ex3-both-anon-regions-one-is-struct-3.rs b/src/test/ui/lifetime-errors/ex3-both-anon-regions-one-is-struct-3.rs
index 5920eeed6b1..4933dbb7e7a 100644
--- a/src/test/ui/lifetime-errors/ex3-both-anon-regions-one-is-struct-3.rs
+++ b/src/test/ui/lifetime-errors/ex3-both-anon-regions-one-is-struct-3.rs
@@ -11,11 +11,7 @@
 struct Ref<'a, 'b> { a: &'a u32, b: &'b u32 }
 
 fn foo(mut y: Ref, x: &u32) {
-<<<<<<< HEAD
     y.b = x;
-=======
-    x = y.b;
->>>>>>> Adding E0623 for structs
 }
 
 fn main() { }
diff --git a/src/test/ui/lifetime-errors/ex3-both-anon-regions-using-fn-items.rs b/src/test/ui/lifetime-errors/ex3-both-anon-regions-using-fn-items.rs
new file mode 100644
index 00000000000..9220c34489f
--- /dev/null
+++ b/src/test/ui/lifetime-errors/ex3-both-anon-regions-using-fn-items.rs
@@ -0,0 +1,14 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+fn foo(x:fn(&u8, &u8), y: Vec<&u8>, z: &u8) {
+  y.push(z);
+}
+
+fn main() { }
diff --git a/src/test/ui/lifetime-errors/ex3-both-anon-regions-using-fn-items.stderr b/src/test/ui/lifetime-errors/ex3-both-anon-regions-using-fn-items.stderr
new file mode 100644
index 00000000000..0913abad3cc
--- /dev/null
+++ b/src/test/ui/lifetime-errors/ex3-both-anon-regions-using-fn-items.stderr
@@ -0,0 +1,10 @@
+error[E0623]: lifetime mismatch
+  --> src/test/ui/lifetime-errors/ex3-both-anon-regions-using-fn-items.rs:11:10
+   |
+10 | fn foo(x:fn(&u8, &u8), y: Vec<&u8>, z: &u8) {
+   |                               ---      --- these two types are declared with different lifetimes...
+11 |   y.push(z);
+   |          ^ ...but data from `z` flows into `y` here
+
+error: aborting due to previous error
+

From 6e3cdcea4c600b89dd067d8af8b7e1738f7df6a5 Mon Sep 17 00:00:00 2001
From: gaurikholkar <f2013002@goa.bits-pilani.ac.in>
Date: Tue, 12 Sep 2017 18:22:22 +0530
Subject: [PATCH 7/8] Adding changes for trait objects

---
 .../infer/error_reporting/different_lifetimes.rs   | 14 ++++++++++++--
 .../ex3-both-anon-regions-using-trait-objects.rs   | 14 ++++++++++++++
 ...x3-both-anon-regions-using-trait-objects.stderr | 10 ++++++++++
 3 files changed, 36 insertions(+), 2 deletions(-)
 create mode 100644 src/test/ui/lifetime-errors/ex3-both-anon-regions-using-trait-objects.rs
 create mode 100644 src/test/ui/lifetime-errors/ex3-both-anon-regions-using-trait-objects.stderr

diff --git a/src/librustc/infer/error_reporting/different_lifetimes.rs b/src/librustc/infer/error_reporting/different_lifetimes.rs
index a54e75857dd..051263dfb53 100644
--- a/src/librustc/infer/error_reporting/different_lifetimes.rs
+++ b/src/librustc/infer/error_reporting/different_lifetimes.rs
@@ -173,6 +173,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             hir_map: &self.tcx.hir,
             bound_region: *br,
             found_type: None,
+            depth: 1,
         };
         nested_visitor.visit_ty(arg);
         nested_visitor.found_type
@@ -195,6 +196,7 @@ struct FindNestedTypeVisitor<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
     // The type where the anonymous lifetime appears
     // for e.g. Vec<`&u8`> and <`&u8`>
     found_type: Option<&'gcx hir::Ty>,
+    depth: u32,
 }
 
 impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindNestedTypeVisitor<'a, 'gcx, 'tcx> {
@@ -211,6 +213,14 @@ impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindNestedTypeVisitor<'a, 'gcx, 'tcx> {
                 return;
             }
 
+            hir::TyTraitObject(ref bounds, _) => {
+                for bound in bounds {
+                    self.depth += 1;
+                    self.visit_poly_trait_ref(bound, hir::TraitBoundModifier::None);
+                    self.depth -= 1;
+                }
+            }
+
             hir::TyRptr(ref lifetime, _) => {
                 // the lifetime of the TyRptr
                 let hir_id = self.infcx.tcx.hir.node_to_hir_id(lifetime.id);
@@ -224,7 +234,7 @@ impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindNestedTypeVisitor<'a, 'gcx, 'tcx> {
                                debruijn_index.depth,
                                anon_index,
                                br_index);
-                        if debruijn_index.depth == 1 && anon_index == br_index {
+                        if debruijn_index.depth == self.depth && anon_index == br_index {
                             self.found_type = Some(arg);
                             return; // we can stop visiting now
                         }
@@ -253,7 +263,7 @@ impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindNestedTypeVisitor<'a, 'gcx, 'tcx> {
                         debug!("self.infcx.tcx.hir.local_def_id(id)={:?}",
                                self.infcx.tcx.hir.local_def_id(id));
                         debug!("def_id={:?}", def_id);
-                        if debruijn_index.depth == 1 &&
+                        if debruijn_index.depth == self.depth &&
                            self.infcx.tcx.hir.local_def_id(id) == def_id {
                             self.found_type = Some(arg);
                             return; // we can stop visiting now
diff --git a/src/test/ui/lifetime-errors/ex3-both-anon-regions-using-trait-objects.rs b/src/test/ui/lifetime-errors/ex3-both-anon-regions-using-trait-objects.rs
new file mode 100644
index 00000000000..78a6ad54eae
--- /dev/null
+++ b/src/test/ui/lifetime-errors/ex3-both-anon-regions-using-trait-objects.rs
@@ -0,0 +1,14 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+fn foo(x:Box<Fn(&u8, &u8)> , y: Vec<&u8>, z: &u8) {
+  y.push(z);
+}
+
+fn main() { }
diff --git a/src/test/ui/lifetime-errors/ex3-both-anon-regions-using-trait-objects.stderr b/src/test/ui/lifetime-errors/ex3-both-anon-regions-using-trait-objects.stderr
new file mode 100644
index 00000000000..ce766b2e406
--- /dev/null
+++ b/src/test/ui/lifetime-errors/ex3-both-anon-regions-using-trait-objects.stderr
@@ -0,0 +1,10 @@
+error[E0623]: lifetime mismatch
+  --> $DIR/ex3-both-anon-regions-using-trait-objects.rs:11:10
+   |
+10 | fn foo(x:Box<Fn(&u8, &u8)> , y: Vec<&u8>, z: &u8) {
+   |                 ---  --- these two types are declared with different lifetimes...
+11 |   y.push(z);
+   |          ^ ...but data from `z` flows into `y` here
+
+error: aborting due to previous error
+

From e71eef1775f9da8bc2e8d312b83df007b4751ec6 Mon Sep 17 00:00:00 2001
From: gaurikholkar <f2013002@goa.bits-pilani.ac.in>
Date: Wed, 13 Sep 2017 20:56:27 +0530
Subject: [PATCH 8/8] fix ui tests

---
 .../ex3-both-anon-regions-both-are-structs-4.stderr             | 2 +-
 .../lifetime-errors/ex3-both-anon-regions-using-fn-items.stderr | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/test/ui/lifetime-errors/ex3-both-anon-regions-both-are-structs-4.stderr b/src/test/ui/lifetime-errors/ex3-both-anon-regions-both-are-structs-4.stderr
index 2ef1cd507f1..689a1ac292b 100644
--- a/src/test/ui/lifetime-errors/ex3-both-anon-regions-both-are-structs-4.stderr
+++ b/src/test/ui/lifetime-errors/ex3-both-anon-regions-both-are-structs-4.stderr
@@ -4,7 +4,7 @@ error[E0623]: lifetime mismatch
 15 | fn foo(mut x: Ref) {
    |               ---
    |               |
-   |               these two types are declared with different lifetimes...
+   |               this type was declared with multiple lifetimes...
 16 |     x.a = x.b;
    |           ^^^ ...but data with one lifetime flows into the other here
 
diff --git a/src/test/ui/lifetime-errors/ex3-both-anon-regions-using-fn-items.stderr b/src/test/ui/lifetime-errors/ex3-both-anon-regions-using-fn-items.stderr
index 0913abad3cc..adfc4dc0c27 100644
--- a/src/test/ui/lifetime-errors/ex3-both-anon-regions-using-fn-items.stderr
+++ b/src/test/ui/lifetime-errors/ex3-both-anon-regions-using-fn-items.stderr
@@ -1,5 +1,5 @@
 error[E0623]: lifetime mismatch
-  --> src/test/ui/lifetime-errors/ex3-both-anon-regions-using-fn-items.rs:11:10
+  --> $DIR/ex3-both-anon-regions-using-fn-items.rs:11:10
    |
 10 | fn foo(x:fn(&u8, &u8), y: Vec<&u8>, z: &u8) {
    |                               ---      --- these two types are declared with different lifetimes...