thread tighter span for closures around

Track the span corresponding to the `|...|` part of the closure.

src/librustc/hir/fold.rs

@@ -1060,10 +1060,11 @@ pub fn noop_fold_expr<T: Folder>(Expr { id, node, span, attrs }: Expr, folder: &
                           arms.move_map(|x| folder.fold_arm(x)),
                           source)
             }
-            ExprClosure(capture_clause, decl, body) => {
+            ExprClosure(capture_clause, decl, body, fn_decl_span) => {
                 ExprClosure(capture_clause,
                             folder.fold_fn_decl(decl),
-                            folder.fold_block(body))
+                            folder.fold_block(body),
+                            folder.new_span(fn_decl_span))
             }
             ExprBlock(blk) => ExprBlock(folder.fold_block(blk)),
             ExprAssign(el, er) => {

src/librustc/hir/intravisit.rs

@@ -785,7 +785,7 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr) {
             visitor.visit_expr(subexpression);
             walk_list!(visitor, visit_arm, arms);
         }
-        ExprClosure(_, ref function_declaration, ref body) => {
+        ExprClosure(_, ref function_declaration, ref body, _fn_decl_span) => {
             visitor.visit_fn(FnKind::Closure(expression.attrs.as_attr_slice()),
                              function_declaration,
                              body,

src/librustc/hir/lowering.rs

@@ -1260,11 +1260,12 @@ pub fn lower_expr(lctx: &LoweringContext, e: &Expr) -> P<hir::Expr> {
                                arms.iter().map(|x| lower_arm(lctx, x)).collect(),
                                hir::MatchSource::Normal)
             }
-            ExprKind::Closure(capture_clause, ref decl, ref body) => {
+            ExprKind::Closure(capture_clause, ref decl, ref body, fn_decl_span) => {
                 lctx.with_parent_def(e.id, || {
                     hir::ExprClosure(lower_capture_clause(lctx, capture_clause),
                                      lower_fn_decl(lctx, decl),
-                                     lower_block(lctx, body))
+                                     lower_block(lctx, body),
+                                     fn_decl_span)
                 })
             }
             ExprKind::Block(ref blk) => hir::ExprBlock(lower_block(lctx, blk)),

src/librustc/hir/map/blocks.rs

@@ -250,7 +250,7 @@ impl<'a> FnLikeNode<'a> {
                 }
             }
             map::NodeExpr(e) => match e.node {
-                ast::ExprClosure(_, ref decl, ref block) =>
+                ast::ExprClosure(_, ref decl, ref block, _fn_decl_span) =>
                     closure(ClosureParts::new(&decl,
                                               &block,
                                               e.id,

src/librustc/hir/mod.rs

@@ -949,8 +949,10 @@ pub enum Expr_ {
     /// A `match` block, with a source that indicates whether or not it is
     /// the result of a desugaring, and if so, which kind.
     ExprMatch(P<Expr>, HirVec<Arm>, MatchSource),
-    /// A closure (for example, `move |a, b, c| {a + b + c}`)
-    ExprClosure(CaptureClause, P<FnDecl>, P<Block>),
+    /// A closure (for example, `move |a, b, c| {a + b + c}`).
+    ///
+    /// The final span is the span of the argument block `|...|`
+    ExprClosure(CaptureClause, P<FnDecl>, P<Block>, Span),
     /// A block (`{ ... }`)
     ExprBlock(P<Block>),
 

src/librustc/hir/print.rs

@@ -1392,7 +1392,7 @@ impl<'a> State<'a> {
                 }
                 self.bclose_(expr.span, indent_unit)?;
             }
-            hir::ExprClosure(capture_clause, ref decl, ref body) => {
+            hir::ExprClosure(capture_clause, ref decl, ref body, _fn_decl_span) => {
                 self.print_capture_clause(capture_clause)?;
 
                 self.print_fn_block_args(&decl)?;

src/librustc/middle/expr_use_visitor.rs

@@ -537,8 +537,8 @@ impl<'d,'t,'a,'tcx> ExprUseVisitor<'d,'t,'a,'tcx> {
                 self.consume_expr(&count);
             }
 
-            hir::ExprClosure(..) => {
-                self.walk_captures(expr)
+            hir::ExprClosure(_, _, _, fn_decl_span) => {
+                self.walk_captures(expr, fn_decl_span)
             }
 
             hir::ExprBox(ref base) => {
@@ -1142,7 +1142,7 @@ impl<'d,'t,'a,'tcx> ExprUseVisitor<'d,'t,'a,'tcx> {
         }));
     }
 
-    fn walk_captures(&mut self, closure_expr: &hir::Expr) {
+    fn walk_captures(&mut self, closure_expr: &hir::Expr, fn_decl_span: Span) {
         debug!("walk_captures({:?})", closure_expr);
 
         self.tcx().with_freevars(closure_expr.id, |freevars| {
@@ -1152,7 +1152,7 @@ impl<'d,'t,'a,'tcx> ExprUseVisitor<'d,'t,'a,'tcx> {
                                              closure_expr_id: closure_expr.id };
                 let upvar_capture = self.typer.upvar_capture(upvar_id).unwrap();
                 let cmt_var = return_if_err!(self.cat_captured_var(closure_expr.id,
-                                                                   closure_expr.span,
+                                                                   fn_decl_span,
                                                                    freevar.def));
                 match upvar_capture {
                     ty::UpvarCapture::ByValue => {
@@ -1161,7 +1161,7 @@ impl<'d,'t,'a,'tcx> ExprUseVisitor<'d,'t,'a,'tcx> {
                     }
                     ty::UpvarCapture::ByRef(upvar_borrow) => {
                         self.delegate.borrow(closure_expr.id,
-                                             closure_expr.span,
+                                             fn_decl_span,
                                              cmt_var,
                                              upvar_borrow.region,
                                              upvar_borrow.kind,

src/librustc/middle/liveness.rs

@@ -948,7 +948,7 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
               self.propagate_through_expr(&e, succ)
           }
 
-          hir::ExprClosure(_, _, ref blk) => {
+          hir::ExprClosure(_, _, ref blk, _) => {
               debug!("{} is an ExprClosure",
                      expr_to_string(expr));
 

src/librustc/middle/mem_categorization.rs

@@ -728,7 +728,7 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
             };
 
             match fn_expr.node {
-                hir::ExprClosure(_, _, ref body) => body.id,
+                hir::ExprClosure(_, _, ref body, _) => body.id,
                 _ => bug!()
             }
         };