Rollup merge of rust-lang#60530 - eddyb:unfreevars, r=oli-obk

rustc: rename all occurences of "freevar" to "upvar".

Most of the more recent code talks about "(closure) upvars", so I believe that's the name we want to use.
There's also the possibility of using "capture" which is more user-facing, but I'd rather not change *both* "freevar" and "upvar" to something else in this one PR.

cc @nikomatsakis @petrochenkov

Author: Manishearth

src/librustc/hir/def.rs

@@ -140,7 +140,7 @@ pub enum Res<Id = hir::HirId> {
     SelfCtor(DefId /* impl */),  // `DefId` refers to the impl
     Local(Id),
     Upvar(Id,           // `HirId` of closed over local
-          usize,        // index in the `freevars` list of the closure
+          usize,        // index in the `upvars` list of the closure
           ast::NodeId), // expr node that creates the closure
 
     // Macro namespace

src/librustc/hir/mod.rs

@@ -2476,19 +2476,19 @@ impl ForeignItemKind {
     }
 }
 
-/// A free variable referred to in a function.
+/// A variable captured by a closure.
 #[derive(Debug, Copy, Clone, RustcEncodable, RustcDecodable, HashStable)]
-pub struct Freevar<Id = HirId> {
-    /// The variable being accessed free.
+pub struct Upvar<Id = HirId> {
+    /// The variable being captured.
     pub res: Res<Id>,
 
     // First span where it is accessed (there can be multiple).
     pub span: Span
 }
 
-impl<Id: fmt::Debug + Copy> Freevar<Id> {
-    pub fn map_id<R>(self, map: impl FnMut(Id) -> R) -> Freevar<R> {
-        Freevar {
+impl<Id: fmt::Debug + Copy> Upvar<Id> {
+    pub fn map_id<R>(self, map: impl FnMut(Id) -> R) -> Upvar<R> {
+        Upvar {
             res: self.res.map_id(map),
             span: self.span,
         }
@@ -2497,12 +2497,12 @@ impl<Id: fmt::Debug + Copy> Freevar<Id> {
     pub fn var_id(&self) -> Id {
         match self.res {
             Res::Local(id) | Res::Upvar(id, ..) => id,
-            _ => bug!("Freevar::var_id: bad res ({:?})", self.res)
+            _ => bug!("Upvar::var_id: bad res ({:?})", self.res)
         }
     }
 }
 
-pub type FreevarMap = NodeMap<Vec<Freevar<ast::NodeId>>>;
+pub type UpvarMap = NodeMap<Vec<Upvar<ast::NodeId>>>;
 
 pub type CaptureModeMap = NodeMap<CaptureClause>;
 

src/librustc/infer/error_reporting/note.rs

@@ -46,7 +46,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                 err.span_note(span,
                               "...so that pointer is not dereferenced outside its lifetime");
             }
-            infer::FreeVariable(span, id) => {
+            infer::ClosureCapture(span, id) => {
                 err.span_note(span,
                               &format!("...so that captured variable `{}` does not outlive the \
                                         enclosing closure",
@@ -214,7 +214,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                     "the reference is only valid for ", sup, "");
                 err
             }
-            infer::FreeVariable(span, id) => {
+            infer::ClosureCapture(span, id) => {
                 let mut err = struct_span_err!(self.tcx.sess,
                                                span,
                                                E0474,

src/librustc/infer/mod.rs

@@ -264,8 +264,8 @@ pub enum SubregionOrigin<'tcx> {
     /// Dereference of reference must be within its lifetime
     DerefPointer(Span),
 
-    /// Closure bound must not outlive captured free variables
-    FreeVariable(Span, ast::NodeId),
+    /// Closure bound must not outlive captured variables
+    ClosureCapture(Span, ast::NodeId),
 
     /// Index into slice must be within its lifetime
     IndexSlice(Span),
@@ -1660,7 +1660,7 @@ impl<'tcx> SubregionOrigin<'tcx> {
             InfStackClosure(a) => a,
             InvokeClosure(a) => a,
             DerefPointer(a) => a,
-            FreeVariable(a, _) => a,
+            ClosureCapture(a, _) => a,
             IndexSlice(a) => a,
             RelateObjectBound(a) => a,
             RelateParamBound(a, _) => a,

src/librustc/middle/expr_use_visitor.rs

@@ -931,42 +931,42 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
         debug!("walk_captures({:?})", closure_expr);
 
         let closure_def_id = self.tcx().hir().local_def_id_from_hir_id(closure_expr.hir_id);
-        self.tcx().with_freevars(closure_expr.hir_id, |freevars| {
-            for freevar in freevars {
-                let var_hir_id = freevar.var_id();
+        if let Some(upvars) = self.tcx().upvars(closure_def_id) {
+            for upvar in upvars.iter() {
+                let var_hir_id = upvar.var_id();
                 let upvar_id = ty::UpvarId {
                     var_path: ty::UpvarPath { hir_id: var_hir_id },
                     closure_expr_id: closure_def_id.to_local(),
                 };
                 let upvar_capture = self.mc.tables.upvar_capture(upvar_id);
                 let cmt_var = return_if_err!(self.cat_captured_var(closure_expr.hir_id,
                                                                    fn_decl_span,
-                                                                   freevar));
+                                                                   upvar));
                 match upvar_capture {
                     ty::UpvarCapture::ByValue => {
                         let mode = copy_or_move(&self.mc,
                                                 self.param_env,
                                                 &cmt_var,
                                                 CaptureMove);
-                        self.delegate.consume(closure_expr.hir_id, freevar.span, &cmt_var, mode);
+                        self.delegate.consume(closure_expr.hir_id, upvar.span, &cmt_var, mode);
                     }
                     ty::UpvarCapture::ByRef(upvar_borrow) => {
                         self.delegate.borrow(closure_expr.hir_id,
                                              fn_decl_span,
                                              &cmt_var,
                                              upvar_borrow.region,
                                              upvar_borrow.kind,
-                                             ClosureCapture(freevar.span));
+                                             ClosureCapture(upvar.span));
                     }
                 }
             }
-        });
+        }
     }
 
     fn cat_captured_var(&mut self,
                         closure_hir_id: hir::HirId,
                         closure_span: Span,
-                        upvar: &hir::Freevar)
+                        upvar: &hir::Upvar)
                         -> mc::McResult<mc::cmt_<'tcx>> {
         // Create the cmt for the variable being borrowed, from the
         // caller's perspective

src/librustc/middle/liveness.rs

@@ -144,7 +144,7 @@ impl LiveNode {
 
 #[derive(Copy, Clone, PartialEq, Debug)]
 enum LiveNodeKind {
-    FreeVarNode(Span),
+    UpvarNode(Span),
     ExprNode(Span),
     VarDefNode(Span),
     ExitNode
@@ -153,8 +153,8 @@ enum LiveNodeKind {
 fn live_node_kind_to_string(lnk: LiveNodeKind, tcx: TyCtxt<'_, '_, '_>) -> String {
     let cm = tcx.sess.source_map();
     match lnk {
-        FreeVarNode(s) => {
-            format!("Free var node [{}]", cm.span_to_string(s))
+        UpvarNode(s) => {
+            format!("Upvar node [{}]", cm.span_to_string(s))
         }
         ExprNode(s) => {
             format!("Expr node [{}]", cm.span_to_string(s))
@@ -483,16 +483,17 @@ fn visit_expr<'a, 'tcx>(ir: &mut IrMaps<'a, 'tcx>, expr: &'tcx Expr) {
         // in better error messages than just pointing at the closure
         // construction site.
         let mut call_caps = Vec::new();
-        ir.tcx.with_freevars(expr.hir_id, |freevars| {
-            call_caps.extend(freevars.iter().filter_map(|fv| {
-                if let Res::Local(rv) = fv.res {
-                    let fv_ln = ir.add_live_node(FreeVarNode(fv.span));
-                    Some(CaptureInfo { ln: fv_ln, var_hid: rv })
+        let closure_def_id = ir.tcx.hir().local_def_id_from_hir_id(expr.hir_id);
+        if let Some(upvars) = ir.tcx.upvars(closure_def_id) {
+            call_caps.extend(upvars.iter().filter_map(|upvar| {
+                if let Res::Local(rv) = upvar.res {
+                    let upvar_ln = ir.add_live_node(UpvarNode(upvar.span));
+                    Some(CaptureInfo { ln: upvar_ln, var_hid: rv })
                 } else {
                     None
                 }
             }));
-        });
+        }
         ir.set_captures(expr.hir_id, call_caps);
 
         intravisit::walk_expr(ir, expr);

src/librustc/mir/mod.rs

@@ -2572,12 +2572,12 @@ impl<'tcx> Debug for Rvalue<'tcx> {
                             };
                             let mut struct_fmt = fmt.debug_struct(&name);
 
-                            tcx.with_freevars(hir_id, |freevars| {
-                                for (freevar, place) in freevars.iter().zip(places) {
-                                    let var_name = tcx.hir().name_by_hir_id(freevar.var_id());
+                            if let Some(upvars) = tcx.upvars(def_id) {
+                                for (upvar, place) in upvars.iter().zip(places) {
+                                    let var_name = tcx.hir().name_by_hir_id(upvar.var_id());
                                     struct_fmt.field(&var_name.as_str(), place);
                                 }
-                            });
+                            }
 
                             struct_fmt.finish()
                         } else {
@@ -2591,12 +2591,12 @@ impl<'tcx> Debug for Rvalue<'tcx> {
                                                tcx.hir().span_by_hir_id(hir_id));
                             let mut struct_fmt = fmt.debug_struct(&name);
 
-                            tcx.with_freevars(hir_id, |freevars| {
-                                for (freevar, place) in freevars.iter().zip(places) {
-                                    let var_name = tcx.hir().name_by_hir_id(freevar.var_id());
+                            if let Some(upvars) = tcx.upvars(def_id) {
+                                for (upvar, place) in upvars.iter().zip(places) {
+                                    let var_name = tcx.hir().name_by_hir_id(upvar.var_id());
                                     struct_fmt.field(&var_name.as_str(), place);
                                 }
-                            });
+                            }
 
                             struct_fmt.finish()
                         } else {

src/librustc/query/mod.rs

@@ -824,7 +824,7 @@ rustc_queries! {
             desc { "generating a postorder list of CrateNums" }
         }
 
-        query freevars(_: DefId) -> Option<Lrc<Vec<hir::Freevar>>> {
+        query upvars(_: DefId) -> Option<Lrc<Vec<hir::Upvar>>> {
             eval_always
         }
         query maybe_unused_trait_import(_: DefId) -> bool {

src/librustc/ty/context.rs

@@ -1071,10 +1071,10 @@ pub struct GlobalCtxt<'tcx> {
 
     pub queries: query::Queries<'tcx>,
 
-    // Records the free variables referenced by every closure
+    // Records the captured variables referenced by every closure
     // expression. Do not track deps for this, just recompute it from
     // scratch every time.
-    freevars: FxHashMap<DefId, Lrc<Vec<hir::Freevar>>>,
+    upvars: FxHashMap<DefId, Lrc<Vec<hir::Upvar>>>,
 
     maybe_unused_trait_imports: FxHashSet<DefId>,
     maybe_unused_extern_crates: Vec<(DefId, Span)>,
@@ -1317,7 +1317,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                 }).collect();
                 (k, Lrc::new(exports))
             }).collect(),
-            freevars: resolutions.freevars.into_iter().map(|(k, v)| {
+            upvars: resolutions.upvars.into_iter().map(|(k, v)| {
                 let vars: Vec<_> = v.into_iter().map(|e| {
                     e.map_id(|id| hir.node_to_hir_id(id))
                 }).collect();
@@ -3055,7 +3055,7 @@ pub fn provide(providers: &mut ty::query::Providers<'_>) {
         assert_eq!(id, LOCAL_CRATE);
         Lrc::new(middle::lang_items::collect(tcx))
     };
-    providers.freevars = |tcx, id| tcx.gcx.freevars.get(&id).cloned();
+    providers.upvars = |tcx, id| tcx.gcx.upvars.get(&id).cloned();
     providers.maybe_unused_trait_import = |tcx, id| {
         tcx.maybe_unused_trait_imports.contains(&id)
     };

src/librustc/ty/mod.rs

@@ -8,8 +8,8 @@ pub use self::BorrowKind::*;
 pub use self::IntVarValue::*;
 pub use self::fold::TypeFoldable;
 
-use crate::hir::{map as hir_map, FreevarMap, GlobMap, TraitMap};
-use crate::hir::{HirId, Node};
+use crate::hir::{map as hir_map, UpvarMap, GlobMap, TraitMap};
+use crate::hir::Node;
 use crate::hir::def::{Res, DefKind, CtorOf, CtorKind, ExportMap};
 use crate::hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_INDEX, LOCAL_CRATE};
 use rustc_data_structures::svh::Svh;
@@ -122,7 +122,7 @@ mod sty;
 
 #[derive(Clone)]
 pub struct Resolutions {
-    pub freevars: FreevarMap,
+    pub upvars: UpvarMap,
     pub trait_map: TraitMap,
     pub maybe_unused_trait_imports: NodeSet,
     pub maybe_unused_extern_crates: Vec<(NodeId, Span)>,
@@ -3120,18 +3120,6 @@ impl Iterator for AssociatedItemsIterator<'_, '_, '_> {
     }
 }
 
-impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
-    pub fn with_freevars<T, F>(self, fid: HirId, f: F) -> T where
-        F: FnOnce(&[hir::Freevar]) -> T,
-    {
-        let def_id = self.hir().local_def_id_from_hir_id(fid);
-        match self.freevars(def_id) {
-            None => f(&[]),
-            Some(d) => f(&d),
-        }
-    }
-}
-
 fn associated_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> AssociatedItem {
     let id = tcx.hir().as_local_hir_id(def_id).unwrap();
     let parent_id = tcx.hir().get_parent_item(id);