Point at variable moved by closure

Author: estebank

src/librustc_borrowck/borrowck/gather_loans/move_error.rs

@@ -11,6 +11,7 @@
 use borrowck::BorrowckCtxt;
 use rustc::middle::mem_categorization as mc;
 use rustc::middle::mem_categorization::Categorization;
+use rustc::middle::mem_categorization::NoteClosureEnv;
 use rustc::middle::mem_categorization::InteriorOffsetKind as Kind;
 use rustc::ty;
 use syntax::ast;
@@ -71,10 +72,12 @@ fn report_move_errors<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
         let mut err = report_cannot_move_out_of(bccx, error.move_from.clone());
         let mut is_first_note = true;
         for move_to in &error.move_to_places {
-            err = note_move_destination(err, move_to.span,
-                                  move_to.name, is_first_note);
+            err = note_move_destination(err, move_to.span, move_to.name, is_first_note);
             is_first_note = false;
         }
+        if let NoteClosureEnv(upvar_id) = error.move_from.note {
+            err.span_label(bccx.tcx.hir.span(upvar_id.var_id), &"captured outer variable");
+        }
         err.emit();
     }
 }

src/test/compile-fail/borrowck/borrowck-in-static.rs src/test/ui/borrowck/borrowck-in-static.rs

@@ -11,7 +11,7 @@
 // check that borrowck looks inside consts/statics
 
 static FN : &'static (Fn() -> (Box<Fn()->Box<i32>>) + Sync) = &|| {
-    let x = Box::new(0);
+    let x = Box::new(0); //~ NOTE moved
     Box::new(|| x) //~ ERROR cannot move out of captured outer variable
 };
 

src/test/ui/borrowck/borrowck-in-static.stderr

@@ -0,0 +1,10 @@
+error[E0507]: cannot move out of captured outer variable in an `Fn` closure
+  --> $DIR/borrowck-in-static.rs:15:17
+   |
+14 |     let x = Box::new(0); //~ NOTE moved
+   |         - captured outer variable
+15 |     Box::new(|| x) //~ ERROR cannot move out of captured outer variable
+   |                 ^ cannot move out of captured outer variable in an `Fn` closure
+
+error: aborting due to previous error
+

src/test/compile-fail/unboxed-closures-move-upvar-from-non-once-ref-closure.rs src/test/ui/borrowck/unboxed-closures-move-upvar-from-non-once-ref-closure.rs

@@ -16,7 +16,7 @@ fn call<F>(f: F) where F : Fn() {
 }
 
 fn main() {
-    let y = vec![format!("World")];
+    let y = vec![format!("World")];  //~ NOTE moved
     call(|| {
         y.into_iter();
         //~^ ERROR cannot move out of captured outer variable in an `Fn` closure

src/test/ui/borrowck/unboxed-closures-move-upvar-from-non-once-ref-closure.stderr

@@ -0,0 +1,11 @@
+error[E0507]: cannot move out of captured outer variable in an `Fn` closure
+  --> $DIR/unboxed-closures-move-upvar-from-non-once-ref-closure.rs:21:9
+   |
+19 |     let y = vec![format!("World")];  //~ NOTE moved
+   |         - captured outer variable
+20 |     call(|| {
+21 |         y.into_iter();
+   |         ^ cannot move out of captured outer variable in an `Fn` closure
+
+error: aborting due to previous error
+

src/test/ui/span/borrowck-call-is-borrow-issue-12224.rs

@@ -21,8 +21,11 @@ struct Test<'a> {
 fn call<F>(mut f: F) where F: FnMut(Fn) {
     f(Box::new(|| {
     //~^ ERROR: cannot borrow `f` as mutable more than once
+    //~| NOTE first mutable borrow occurs here
+    //~| NOTE second mutable borrow occurs here
         f((Box::new(|| {})))
     }));
+    //~^ NOTE first borrow ends here
 }
 
 fn test1() {
@@ -32,15 +35,21 @@ fn test1() {
 }
 
 fn test2<F>(f: &F) where F: FnMut() {
-    (*f)(); //~ ERROR: cannot borrow immutable borrowed content `*f` as mutable
+    //~^ NOTE use `&mut F` here to make mutable
+    (*f)();
+    //~^ ERROR cannot borrow immutable borrowed content `*f` as mutable
+    //~| NOTE cannot borrow as mutable
 }
 
 fn test3<F>(f: &mut F) where F: FnMut() {
     (*f)();
 }
 
 fn test4(f: &Test) {
-    f.f.call_mut(()) //~ ERROR: cannot borrow immutable `Box` content `*f.f` as mutable
+    //~^ NOTE use `&mut Test` here to make mutable
+    f.f.call_mut(())
+    //~^ ERROR: cannot borrow immutable `Box` content `*f.f` as mutable
+    //~| NOTE cannot borrow as mutable
 }
 
 fn test5(f: &mut Test) {
@@ -57,10 +66,14 @@ fn test6() {
 fn test7() {
     fn foo<F>(_: F) where F: FnMut(Box<FnMut(isize)>, isize) {}
     let mut f = |g: Box<FnMut(isize)>, b: isize| {};
+    //~^ NOTE moved
     f(Box::new(|a| {
+    //~^ NOTE borrow of `f` occurs here
         foo(f);
         //~^ ERROR cannot move `f` into closure because it is borrowed
         //~| ERROR cannot move out of captured outer variable in an `FnMut` closure
+        //~| NOTE move into closure occurs here
+        //~| NOTE cannot move out of captured outer variable in an `FnMut` closure
     }), 3);
 }
 

src/test/ui/span/borrowck-call-is-borrow-issue-12224.stderr

@@ -5,40 +5,46 @@ error[E0499]: cannot borrow `f` as mutable more than once at a time
    |     -          ^^ second mutable borrow occurs here
    |     |
    |     first mutable borrow occurs here
-23 |     //~^ ERROR: cannot borrow `f` as mutable more than once
-24 |         f((Box::new(|| {})))
+...
+26 |         f((Box::new(|| {})))
    |         - borrow occurs due to use of `f` in closure
-25 |     }));
+27 |     }));
    |       - first borrow ends here
 
 error: cannot borrow immutable borrowed content `*f` as mutable
-  --> $DIR/borrowck-call-is-borrow-issue-12224.rs:35:5
+  --> $DIR/borrowck-call-is-borrow-issue-12224.rs:39:5
    |
-34 | fn test2<F>(f: &F) where F: FnMut() {
+37 | fn test2<F>(f: &F) where F: FnMut() {
    |                -- use `&mut F` here to make mutable
-35 |     (*f)(); //~ ERROR: cannot borrow immutable borrowed content `*f` as mutable
+38 |     //~^ NOTE use `&mut F` here to make mutable
+39 |     (*f)();
    |     ^^^^ cannot borrow as mutable
 
 error: cannot borrow immutable `Box` content `*f.f` as mutable
-  --> $DIR/borrowck-call-is-borrow-issue-12224.rs:43:5
+  --> $DIR/borrowck-call-is-borrow-issue-12224.rs:50:5
    |
-42 | fn test4(f: &Test) {
+48 | fn test4(f: &Test) {
    |             ----- use `&mut Test` here to make mutable
-43 |     f.f.call_mut(()) //~ ERROR: cannot borrow immutable `Box` content `*f.f` as mutable
+49 |     //~^ NOTE use `&mut Test` here to make mutable
+50 |     f.f.call_mut(())
    |     ^^^ cannot borrow as mutable
 
 error[E0504]: cannot move `f` into closure because it is borrowed
-  --> $DIR/borrowck-call-is-borrow-issue-12224.rs:61:13
+  --> $DIR/borrowck-call-is-borrow-issue-12224.rs:72:13
    |
-60 |     f(Box::new(|a| {
+70 |     f(Box::new(|a| {
    |     - borrow of `f` occurs here
-61 |         foo(f);
+71 |     //~^ NOTE borrow of `f` occurs here
+72 |         foo(f);
    |             ^ move into closure occurs here
 
 error[E0507]: cannot move out of captured outer variable in an `FnMut` closure
-  --> $DIR/borrowck-call-is-borrow-issue-12224.rs:61:13
+  --> $DIR/borrowck-call-is-borrow-issue-12224.rs:72:13
    |
-61 |         foo(f);
+68 |     let mut f = |g: Box<FnMut(isize)>, b: isize| {};
+   |         ----- captured outer variable
+...
+72 |         foo(f);
    |             ^ cannot move out of captured outer variable in an `FnMut` closure
 
 error: aborting due to 5 previous errors