Auto merge of #43324 - Nashenas88:visit_locations, r=arielb1

Provide positional information when visiting ty, substs and closure_substs in MIR

This will enable the region renumbering portion of #43234 (non-lexical lifetimes). @nikomatsakis's current plan [here](https://gist.github.com/nikomatsakis/dfc27b28cd024eb25054b52bb11082f2) shows that we need spans of the original code to create new region variables, e.g. `self.infcx.next_region_var(infer::MiscVariable(span))`. The current visitor impls did not pass positional information (`Location` in some, `Span` and `SourceInfo` for others) for all types. I did not expand this to all visits, just the ones necessary for the above-mentioned plan.

4 files changed, 37 insertions, 23 deletions

diff --git a/src/librustc/mir/visit.rs b/src/librustc/mir/visit.rs
index ac1c0306f70..fd3a9f8cd2d 100644
--- a/src/librustc/mir/visit.rs
+++ b/src/librustc/mir/visit.rs
@@ -210,17 +210,20 @@ macro_rules! make_mir_visitor {
             }
 
             fn visit_ty(&mut self,
-                        ty: & $($mutability)* Ty<'tcx>) {
+                        ty: & $($mutability)* Ty<'tcx>,
+                        _: Lookup) {
                 self.super_ty(ty);
             }
 
             fn visit_substs(&mut self,
-                            substs: & $($mutability)* &'tcx Substs<'tcx>) {
+                            substs: & $($mutability)* &'tcx Substs<'tcx>,
+                            _: Location) {
                 self.super_substs(substs);
             }
 
             fn visit_closure_substs(&mut self,
-                                    substs: & $($mutability)* ClosureSubsts<'tcx>) {
+                                    substs: & $($mutability)* ClosureSubsts<'tcx>,
+                                    _: Location) {
                 self.super_closure_substs(substs);
             }
 
@@ -266,7 +269,11 @@ macro_rules! make_mir_visitor {
                     self.visit_visibility_scope_data(scope);
                 }
 
-                self.visit_ty(&$($mutability)* mir.return_ty);
+                let lookup = Lookup::Src(SourceInfo {
+                    span: mir.span,
+                    scope: ARGUMENT_VISIBILITY_SCOPE,
+                });
+                self.visit_ty(&$($mutability)* mir.return_ty, lookup);
 
                 for local_decl in &$($mutability)* mir.local_decls {
                     self.visit_local_decl(local_decl);
@@ -385,7 +392,7 @@ macro_rules! make_mir_visitor {
                                                 ref values,
                                                 ref targets } => {
                         self.visit_operand(discr, source_location);
-                        self.visit_ty(switch_ty);
+                        self.visit_ty(switch_ty, Lookup::Loc(source_location));
                         for value in &values[..] {
                             self.visit_const_int(value, source_location);
                         }
@@ -489,7 +496,7 @@ macro_rules! make_mir_visitor {
                                  ref $($mutability)* operand,
                                  ref $($mutability)* ty) => {
                         self.visit_operand(operand, location);
-                        self.visit_ty(ty);
+                        self.visit_ty(ty, Lookup::Loc(location));
                     }
 
                     Rvalue::BinaryOp(_bin_op,
@@ -511,7 +518,7 @@ macro_rules! make_mir_visitor {
                     }
 
                     Rvalue::NullaryOp(_op, ref $($mutability)* ty) => {
-                        self.visit_ty(ty);
+                        self.visit_ty(ty, Lookup::Loc(location));
                     }
 
                     Rvalue::Aggregate(ref $($mutability)* kind,
@@ -519,7 +526,7 @@ macro_rules! make_mir_visitor {
                         let kind = &$($mutability)* **kind;
                         match *kind {
                             AggregateKind::Array(ref $($mutability)* ty) => {
-                                self.visit_ty(ty);
+                                self.visit_ty(ty, Lookup::Loc(location));
                             }
                             AggregateKind::Tuple => {
                             }
@@ -527,12 +534,12 @@ macro_rules! make_mir_visitor {
                                                _variant_index,
                                                ref $($mutability)* substs,
                                                _active_field_index) => {
-                                self.visit_substs(substs);
+                                self.visit_substs(substs, location);
                             }
                             AggregateKind::Closure(ref $($mutability)* def_id,
                                                    ref $($mutability)* closure_substs) => {
                                 self.visit_def_id(def_id, location);
-                                self.visit_closure_substs(closure_substs);
+                                self.visit_closure_substs(closure_substs, location);
                             }
                         }
 
@@ -581,7 +588,7 @@ macro_rules! make_mir_visitor {
                     ref $($mutability)* ty,
                 } = *static_;
                 self.visit_def_id(def_id, location);
-                self.visit_ty(ty);
+                self.visit_ty(ty, Lookup::Loc(location));
             }
 
             fn super_projection(&mut self,
@@ -611,7 +618,7 @@ macro_rules! make_mir_visitor {
                     ProjectionElem::Subslice { from: _, to: _ } => {
                     }
                     ProjectionElem::Field(_field, ref $($mutability)* ty) => {
-                        self.visit_ty(ty);
+                        self.visit_ty(ty, Lookup::Loc(location));
                     }
                     ProjectionElem::Index(ref $($mutability)* operand) => {
                         self.visit_operand(operand, location);
@@ -635,7 +642,7 @@ macro_rules! make_mir_visitor {
                     is_user_variable: _,
                 } = *local_decl;
 
-                self.visit_ty(ty);
+                self.visit_ty(ty, Lookup::Src(*source_info));
                 self.visit_source_info(source_info);
             }
 
@@ -658,7 +665,7 @@ macro_rules! make_mir_visitor {
                 } = *constant;
 
                 self.visit_span(span);
-                self.visit_ty(ty);
+                self.visit_ty(ty, Lookup::Loc(location));
                 self.visit_literal(literal, location);
             }
 
@@ -669,7 +676,7 @@ macro_rules! make_mir_visitor {
                     Literal::Item { ref $($mutability)* def_id,
                                     ref $($mutability)* substs } => {
                         self.visit_def_id(def_id, location);
-                        self.visit_substs(substs);
+                        self.visit_substs(substs, location);
                     }
                     Literal::Value { ref $($mutability)* value } => {
                         self.visit_const_val(value, location);
@@ -734,6 +741,11 @@ macro_rules! make_mir_visitor {
 make_mir_visitor!(Visitor,);
 make_mir_visitor!(MutVisitor,mut);
 
+pub enum Lookup {
+    Loc(Location),
+    Src(SourceInfo),
+}
+
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub enum LvalueContext<'tcx> {
     // Appears as LHS of an assignment
diff --git a/src/librustc_mir/build/mod.rs b/src/librustc_mir/build/mod.rs
index 5badef3cfa1..3353fb9a5b4 100644
--- a/src/librustc_mir/build/mod.rs
+++ b/src/librustc_mir/build/mod.rs
@@ -17,7 +17,7 @@ use rustc::hir::def_id::DefId;
 use rustc::middle::region::CodeExtent;
 use rustc::mir::*;
 use rustc::mir::transform::MirSource;
-use rustc::mir::visit::MutVisitor;
+use rustc::mir::visit::{MutVisitor, Lookup};
 use rustc::ty::{self, Ty, TyCtxt};
 use rustc::ty::subst::Substs;
 use rustc::util::nodemap::NodeMap;
@@ -143,7 +143,7 @@ struct GlobalizeMir<'a, 'gcx: 'a> {
 }
 
 impl<'a, 'gcx: 'tcx, 'tcx> MutVisitor<'tcx> for GlobalizeMir<'a, 'gcx> {
-    fn visit_ty(&mut self, ty: &mut Ty<'tcx>) {
+    fn visit_ty(&mut self, ty: &mut Ty<'tcx>, _: Lookup) {
         if let Some(lifted) = self.tcx.lift(ty) {
             *ty = lifted;
         } else {
@@ -153,7 +153,7 @@ impl<'a, 'gcx: 'tcx, 'tcx> MutVisitor<'tcx> for GlobalizeMir<'a, 'gcx> {
         }
     }
 
-    fn visit_substs(&mut self, substs: &mut &'tcx Substs<'tcx>) {
+    fn visit_substs(&mut self, substs: &mut &'tcx Substs<'tcx>, _: Location) {
         if let Some(lifted) = self.tcx.lift(substs) {
             *substs = lifted;
         } else {
diff --git a/src/librustc_mir/transform/erase_regions.rs b/src/librustc_mir/transform/erase_regions.rs
index eb283df869f..da9032685e0 100644
--- a/src/librustc_mir/transform/erase_regions.rs
+++ b/src/librustc_mir/transform/erase_regions.rs
@@ -15,7 +15,7 @@
 use rustc::ty::subst::Substs;
 use rustc::ty::{Ty, TyCtxt, ClosureSubsts};
 use rustc::mir::*;
-use rustc::mir::visit::MutVisitor;
+use rustc::mir::visit::{MutVisitor, Lookup};
 use rustc::mir::transform::{MirPass, MirSource};
 
 struct EraseRegionsVisitor<'a, 'tcx: 'a> {
@@ -31,12 +31,12 @@ impl<'a, 'tcx> EraseRegionsVisitor<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> MutVisitor<'tcx> for EraseRegionsVisitor<'a, 'tcx> {
-    fn visit_ty(&mut self, ty: &mut Ty<'tcx>) {
+    fn visit_ty(&mut self, ty: &mut Ty<'tcx>, _: Lookup) {
         let old_ty = *ty;
         *ty = self.tcx.erase_regions(&old_ty);
     }
 
-    fn visit_substs(&mut self, substs: &mut &'tcx Substs<'tcx>) {
+    fn visit_substs(&mut self, substs: &mut &'tcx Substs<'tcx>, _: Location) {
         *substs = self.tcx.erase_regions(&{*substs});
     }
 
@@ -62,7 +62,8 @@ impl<'a, 'tcx> MutVisitor<'tcx> for EraseRegionsVisitor<'a, 'tcx> {
     }
 
     fn visit_closure_substs(&mut self,
-                            substs: &mut ClosureSubsts<'tcx>) {
+                            substs: &mut ClosureSubsts<'tcx>,
+                            _: Location) {
         *substs = self.tcx.erase_regions(substs);
     }
 
diff --git a/src/librustc_passes/mir_stats.rs b/src/librustc_passes/mir_stats.rs
index 4dd38cc515c..9895802700e 100644
--- a/src/librustc_passes/mir_stats.rs
+++ b/src/librustc_passes/mir_stats.rs
@@ -279,7 +279,8 @@ impl<'a, 'tcx> mir_visit::Visitor<'tcx> for StatCollector<'a, 'tcx> {
     }
 
     fn visit_closure_substs(&mut self,
-                            substs: &ClosureSubsts<'tcx>) {
+                            substs: &ClosureSubsts<'tcx>,
+                            _: Location) {
         self.record("ClosureSubsts", substs);
         self.super_closure_substs(substs);
     }