auto merge of #20432 : nikomatsakis/rust/fn-inference-2, r=eddyb

Previously, the borrow mode of each upvar was inferred as part of regionck. This PR moves it into its own separate step. It also employs the `ExprUseVisitor`, further simplifying the code. The eventual goal is to support better inference of `Fn` vs `FnMut` vs `FnOnce` that is not based on the expected type, as well as supporting individual by-move upvars.

r? @eddyb

Author: bors

src/librustc/lint/builtin.rs

@@ -1612,15 +1612,11 @@ impl LintPass for MissingCopyImplementations {
             }
             _ => return,
         };
-        let parameter_environment = ty::empty_parameter_environment();
-        if !ty::type_moves_by_default(cx.tcx,
-                                      ty,
-                                      &parameter_environment) {
+        let parameter_environment = ty::empty_parameter_environment(cx.tcx);
+        if !ty::type_moves_by_default(&parameter_environment, item.span, ty) {
             return
         }
-        if ty::can_type_implement_copy(cx.tcx,
-                                       ty,
-                                       &parameter_environment).is_ok() {
+        if ty::can_type_implement_copy(&parameter_environment, item.span, ty).is_ok() {
             cx.span_lint(MISSING_COPY_IMPLEMENTATIONS,
                          item.span,
                          "type could implement `Copy`; consider adding `impl \

src/librustc/middle/check_match.rs

@@ -99,7 +99,7 @@ impl<'a> FromIterator<Vec<&'a Pat>> for Matrix<'a> {
 
 pub struct MatchCheckCtxt<'a, 'tcx: 'a> {
     pub tcx: &'a ty::ctxt<'tcx>,
-    pub param_env: ParameterEnvironment<'tcx>,
+    pub param_env: ParameterEnvironment<'a, 'tcx>,
 }
 
 #[deriving(Clone, PartialEq)]
@@ -148,7 +148,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for MatchCheckCtxt<'a, 'tcx> {
 pub fn check_crate(tcx: &ty::ctxt) {
     visit::walk_crate(&mut MatchCheckCtxt {
         tcx: tcx,
-        param_env: ty::empty_parameter_environment(),
+        param_env: ty::empty_parameter_environment(tcx),
     }, tcx.map.krate());
     tcx.sess.abort_if_errors();
 }
@@ -1032,9 +1032,7 @@ fn check_legality_of_move_bindings(cx: &MatchCheckCtxt,
                 match p.node {
                     ast::PatIdent(ast::BindByValue(_), _, ref sub) => {
                         let pat_ty = ty::node_id_to_type(tcx, p.id);
-                        if ty::type_moves_by_default(tcx,
-                                                      pat_ty,
-                                                      &cx.param_env) {
+                        if ty::type_moves_by_default(&cx.param_env, pat.span, pat_ty) {
                             check_move(p, sub.as_ref().map(|p| &**p));
                         }
                     }
@@ -1063,8 +1061,7 @@ fn check_for_mutation_in_guard<'a, 'tcx>(cx: &'a MatchCheckCtxt<'a, 'tcx>,
         cx: cx,
     };
     let mut visitor = ExprUseVisitor::new(&mut checker,
-                                          checker.cx.tcx,
-                                          &cx.param_env);
+                                          &checker.cx.param_env);
     visitor.walk_expr(guard);
 }
 

src/librustc/middle/check_rvalues.rs

@@ -41,7 +41,7 @@ impl<'a, 'tcx, 'v> visit::Visitor<'v> for RvalueContext<'a, 'tcx> {
         {
             let param_env = ParameterEnvironment::for_item(self.tcx, fn_id);
             let mut delegate = RvalueContextDelegate { tcx: self.tcx, param_env: &param_env };
-            let mut euv = euv::ExprUseVisitor::new(&mut delegate, self.tcx, &param_env);
+            let mut euv = euv::ExprUseVisitor::new(&mut delegate, &param_env);
             euv.walk_fn(fd, b);
         }
         visit::walk_fn(self, fk, fd, b, s)
@@ -50,7 +50,7 @@ impl<'a, 'tcx, 'v> visit::Visitor<'v> for RvalueContext<'a, 'tcx> {
 
 struct RvalueContextDelegate<'a, 'tcx: 'a> {
     tcx: &'a ty::ctxt<'tcx>,
-    param_env: &'a ty::ParameterEnvironment<'tcx>,
+    param_env: &'a ty::ParameterEnvironment<'a,'tcx>,
 }
 
 impl<'a, 'tcx> euv::Delegate<'tcx> for RvalueContextDelegate<'a, 'tcx> {
@@ -60,7 +60,7 @@ impl<'a, 'tcx> euv::Delegate<'tcx> for RvalueContextDelegate<'a, 'tcx> {
                cmt: mc::cmt<'tcx>,
                _: euv::ConsumeMode) {
         debug!("consume; cmt: {}; type: {}", *cmt, ty_to_string(self.tcx, cmt.ty));
-        if !ty::type_is_sized(self.tcx, cmt.ty, self.param_env) {
+        if !ty::type_is_sized(self.param_env, span, cmt.ty) {
             span_err!(self.tcx.sess, span, E0161,
                 "cannot move a value of type {0}: the size of {0} cannot be statically determined",
                 ty_to_string(self.tcx, cmt.ty));

src/librustc/middle/check_static.rs

@@ -54,7 +54,7 @@ struct CheckStaticVisitor<'a, 'tcx: 'a> {
 }
 
 struct GlobalVisitor<'a,'b,'tcx:'a+'b>(
-    euv::ExprUseVisitor<'a,'b,'tcx,ty::ctxt<'tcx>>);
+    euv::ExprUseVisitor<'a,'b,'tcx,ty::ParameterEnvironment<'b,'tcx>>);
 struct GlobalChecker {
     static_consumptions: NodeSet,
     const_borrows: NodeSet,
@@ -70,8 +70,8 @@ pub fn check_crate(tcx: &ty::ctxt) {
         static_local_borrows: NodeSet::new(),
     };
     {
-        let param_env = ty::empty_parameter_environment();
-        let visitor = euv::ExprUseVisitor::new(&mut checker, tcx, &param_env);
+        let param_env = ty::empty_parameter_environment(tcx);
+        let visitor = euv::ExprUseVisitor::new(&mut checker, &param_env);
         visit::walk_crate(&mut GlobalVisitor(visitor), tcx.map.krate());
     }
     visit::walk_crate(&mut CheckStaticVisitor {
@@ -121,8 +121,8 @@ impl<'a, 'tcx> CheckStaticVisitor<'a, 'tcx> {
         let mut fulfill_cx = traits::FulfillmentContext::new();
         let cause = traits::ObligationCause::new(e.span, e.id, traits::SharedStatic);
         fulfill_cx.register_builtin_bound(&infcx, ty, ty::BoundSync, cause);
-        let env = ty::empty_parameter_environment();
-        match fulfill_cx.select_all_or_error(&infcx, &env, self.tcx) {
+        let env = ty::empty_parameter_environment(self.tcx);
+        match fulfill_cx.select_all_or_error(&infcx, &env) {
             Ok(()) => { },
             Err(ref errors) => {
                 traits::report_fulfillment_errors(&infcx, errors);

src/librustc/middle/def.rs

@@ -126,6 +126,12 @@ impl TraitItemKind {
 }
 
 impl Def {
+    pub fn local_node_id(&self) -> ast::NodeId {
+        let def_id = self.def_id();
+        assert_eq!(def_id.krate, ast::LOCAL_CRATE);
+        def_id.node
+    }
+
     pub fn def_id(&self) -> ast::DefId {
         match *self {
             DefFn(id, _) | DefStaticMethod(id, _) | DefMod(id) |