Add better error message for partial move

src/librustc_mir/borrow_check/error_reporting.rs

@@ -130,13 +130,15 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
  );
 
  let mut is_loop_move = false;
+ let mut is_partial_move = false;
  for move_site in &move_site_vec {
  let move_out = self.move_data.moves[(*move_site).moi];
  let moved_place = &self.move_data.move_paths[move_out.path].place;
 
  let move_spans = self.move_spans(moved_place, move_out.source);
  let move_span = move_spans.args_or_use();
 
+ is_partial_move = used_place.is_prefix_of(moved_place);
  let move_msg = if move_spans.for_closure() {
  " into closure"
  } else {
@@ -175,8 +177,9 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
  err.span_label(
  span,
  format!(
- "value {} here after move",
- desired_action.as_verb_in_past_tense()
+ "value {} here {}",
+ desired_action.as_verb_in_past_tense(),
+ if is_partial_move { "after partial move" } else { "after move" },
  ),
  );
  }

src/test/ui/borrowck/borrowck-asm.mir.stderr

@@ -8,7 +8,7 @@ LL | asm!("nop" : : "r"(x));
  | - value moved here
 LL | }
 LL | let z = x; //[ast]~ ERROR use of moved value: `x`
- | ^ value used here after move
+ | ^ value used here after partial move
 
 error[E0503]: cannot use `x` because it was mutably borrowed
  --> $DIR/borrowck-asm.rs:35:32
@@ -71,7 +71,7 @@ LL | let x = &mut 2;
  | - move occurs because `x` has type `&mut i32`, which does not implement the `Copy` trait
 LL | unsafe {
 LL | asm!("nop" : : "r"(x), "r"(x) ); //[ast]~ ERROR use of moved value
- | - ^ value used here after move
+ | - ^ value used here after partial move
  | |
  | value moved here
 

src/test/ui/borrowck/borrowck-describe-lvalue.mir.stderr

@@ -367,7 +367,7 @@ error[E0382]: use of moved value: `x`
 LL | drop(x);
  | - value moved here
 LL | drop(x); //[ast]~ ERROR use of moved value: `x`
- | ^ value used here after move
+ | ^ value used here after partial move
  |
  = note: move occurs because `x` has type `std::vec::Vec<i32>`, which does not implement the `Copy` trait
 

src/test/ui/borrowck/borrowck-drop-from-guard.stderr

@@ -8,7 +8,7 @@ LL | Some(_) if { drop(my_str); false } => {}
  | ------ value moved here
 LL | Some(_) => {}
 LL | None => { foo(my_str); } //~ ERROR [E0382]
- | ^^^^^^ value used here after move
+ | ^^^^^^ value used here after partial move
 
 error: aborting due to previous error
 

src/test/ui/borrowck/borrowck-issue-48962.stderr

@@ -6,7 +6,7 @@ LL | let mut src = &mut node;
 LL | {src};
  | --- value moved here
 LL | src.next = None; //~ ERROR use of moved value: `src` [E0382]
- | ^^^^^^^^ value used here after move
+ | ^^^^^^^^ value used here after partial move
 
 error[E0382]: use of moved value: `src`
  --> $DIR/borrowck-issue-48962.rs:22:5
@@ -16,7 +16,7 @@ LL | let mut src = &mut (22, 44);
 LL | {src};
  | --- value moved here
 LL | src.0 = 66; //~ ERROR use of moved value: `src` [E0382]
- | ^^^^^^^^^^ value used here after move
+ | ^^^^^^^^^^ value used here after partial move
 
 error: aborting due to 2 previous errors
 

src/test/ui/borrowck/borrowck-move-moved-value-into-closure.mir.stderr

@@ -11,7 +11,7 @@ LL | call_f(move|| { *t + 1 });
 LL | call_f(move|| { *t + 1 }); //[ast]~ ERROR capture of moved value
  | ^^^^^^ - use occurs due to use in closure
  | |
- | value used here after move
+ | value used here after partial move
 
 error: aborting due to previous error
 

src/test/ui/borrowck/borrowck-move-out-from-array.mir.stderr

@@ -4,7 +4,7 @@ error[E0382]: use of moved value: `a[..]`
 LL | let [_, _x] = a;
  | -- value moved here
 LL | let [.., _y] = a; //[ast]~ ERROR [E0382]
- | ^^ value used here after move
+ | ^^ value used here after partial move
  |
  = note: move occurs because `a[..]` has type `std::boxed::Box<i32>`, which does not implement the `Copy` trait
 
@@ -14,7 +14,7 @@ error[E0382]: use of moved value: `a[..]`
 LL | let [_x, _] = a;
  | -- value moved here
 LL | let [_y..] = a; //[ast]~ ERROR [E0382]
- | ^^ value used here after move
+ | ^^ value used here after partial move
  |
  = note: move occurs because `a[..]` has type `std::boxed::Box<i32>`, which does not implement the `Copy` trait
 

src/test/ui/borrowck/borrowck-reinit.stderr

@@ -17,7 +17,7 @@ LL | let mut x = Box::new(0);
 LL | drop(x);
  | - value moved here
 LL | let _ = (1,x); //~ ERROR use of moved value: `x` (Ast)
- | ^ value used here after move
+ | ^ value used here after partial move
 
 error: aborting due to 2 previous errors
 

src/test/ui/borrowck/borrowck-uninit-field-access.mir.stderr

@@ -20,7 +20,7 @@ error[E0382]: use of moved value: `line2`
 LL | let _moved = (line2.origin, line2.middle);
  | ------------ value moved here
 LL | line2.consume(); //[ast]~ ERROR use of partially moved value: `line2` [E0382]
- | ^^^^^ value used here after move
+ | ^^^^^ value used here after partial move
  |
  = note: move occurs because `line2.middle` has type `Point`, which does not implement the `Copy` trait
 

src/test/ui/borrowck/issue-54499-field-mutation-of-moved-out-with-mut.nll.stderr

@@ -6,7 +6,7 @@ LL | let mut t: Tuple = (S(0), 0);
 LL | drop(t);
  | - value moved here
 LL | t.0 = S(1);
- | ^^^^^^^^^^ value partially assigned here after move
+ | ^^^^^^^^^^ value partially assigned here after partial move
 
 error[E0382]: assign to part of moved value: `u`
  --> $DIR/issue-54499-field-mutation-of-moved-out-with-mut.rs:34:9
@@ -16,7 +16,7 @@ LL | let mut u: Tpair = Tpair(S(0), 0);
 LL | drop(u);
  | - value moved here
 LL | u.0 = S(1);
- | ^^^^^^^^^^ value partially assigned here after move
+ | ^^^^^^^^^^ value partially assigned here after partial move
 
 error[E0382]: assign to part of moved value: `v`
  --> $DIR/issue-54499-field-mutation-of-moved-out-with-mut.rs:45:9
@@ -26,7 +26,7 @@ LL | let mut v: Spair = Spair { x: S(0), y: 0 };
 LL | drop(v);
  | - value moved here
 LL | v.x = S(1);
- | ^^^^^^^^^^ value partially assigned here after move
+ | ^^^^^^^^^^ value partially assigned here after partial move
 
 error: aborting due to 3 previous errors
 

src/test/ui/borrowck/issue-54499-field-mutation-of-moved-out.nll.stderr

@@ -15,7 +15,7 @@ LL | let t: Tuple = (S(0), 0);
 LL | drop(t);
  | - value moved here
 LL | t.0 = S(1);
- | ^^^^^^^^^^ value partially assigned here after move
+ | ^^^^^^^^^^ value partially assigned here after partial move
 
 error[E0594]: cannot assign to `t.1`, as `t` is not declared as mutable
  --> $DIR/issue-54499-field-mutation-of-moved-out.rs:27:9
@@ -43,7 +43,7 @@ LL | let u: Tpair = Tpair(S(0), 0);
 LL | drop(u);
  | - value moved here
 LL | u.0 = S(1);
- | ^^^^^^^^^^ value partially assigned here after move
+ | ^^^^^^^^^^ value partially assigned here after partial move
 
 error[E0594]: cannot assign to `u.1`, as `u` is not declared as mutable
  --> $DIR/issue-54499-field-mutation-of-moved-out.rs:42:9
@@ -71,7 +71,7 @@ LL | let v: Spair = Spair { x: S(0), y: 0 };
 LL | drop(v);
  | - value moved here
 LL | v.x = S(1);
- | ^^^^^^^^^^ value partially assigned here after move
+ | ^^^^^^^^^^ value partially assigned here after partial move
 
 error[E0594]: cannot assign to `v.y`, as `v` is not declared as mutable
  --> $DIR/issue-54499-field-mutation-of-moved-out.rs:57:9

src/test/ui/borrowck/two-phase-nonrecv-autoref.nll.stderr

@@ -13,7 +13,7 @@ error[E0382]: use of moved value: `*f`
 LL | fn twice_ten_so<F: FnOnce(i32) -> i32>(f: Box<F>) {
  | - consider adding a `Copy` constraint to this type argument
 LL | f(f(10));
- | - ^ value used here after move
+ | - ^ value used here after partial move
  | |
  | value moved here
  |
@@ -44,7 +44,7 @@ error[E0382]: use of moved value: `*f`
  --> $DIR/two-phase-nonrecv-autoref.rs:85:11
  |
 LL | f(f(10));
- | - ^ value used here after move
+ | - ^ value used here after partial move
  | |
  | value moved here
  |

src/test/ui/issues/issue-29723.stderr

@@ -8,7 +8,7 @@ LL | 0 if { drop(s); false } => String::from("oops"),
  | - value moved here
 ...
 LL | s
- | ^ value used here after move
+ | ^ value used here after partial move
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-34721.stderr

@@ -13,7 +13,7 @@ LL | x.zero()
  | - value moved here
 LL | };
 LL | x.zero()
- | ^ value used here after move
+ | ^ value used here after partial move
 
 error: aborting due to previous error
 

src/test/ui/moves/moves-based-on-type-tuple.stderr

@@ -14,7 +14,7 @@ error[E0382]: use of moved value: `x` (Mir)
 LL | fn dup(x: Box<isize>) -> Box<(Box<isize>,Box<isize>)> {
  | - move occurs because `x` has type `std::boxed::Box<isize>`, which does not implement the `Copy` trait
 LL | box (x, x)
- | - ^ value used here after move
+ | - ^ value used here after partial move
  | |
  | value moved here
 

src/test/ui/nll/closure-access-spans.stderr

@@ -66,7 +66,7 @@ LL | let r = x;
 LL | || x.len(); //~ ERROR
  | ^^ - borrow occurs due to use in closure
  | |
- | value borrowed here after move
+ | value borrowed here after partial move
 
 error[E0382]: borrow of moved value: `x`
  --> $DIR/closure-access-spans.rs:42:5
@@ -78,7 +78,7 @@ LL | let r = x;
 LL | || x = String::new(); //~ ERROR
  | ^^ - borrow occurs due to use in closure
  | |
- | value borrowed here after move
+ | value borrowed here after partial move
 
 error[E0382]: borrow of moved value: `x`
  --> $DIR/closure-access-spans.rs:47:5
@@ -90,7 +90,7 @@ LL | let r = x;
 LL | || *x = String::new(); //~ ERROR
  | ^^ - borrow occurs due to use in closure
  | |
- | value borrowed here after move
+ | value borrowed here after partial move
 
 error[E0382]: use of moved value: `x`
  --> $DIR/closure-access-spans.rs:52:5
@@ -102,7 +102,7 @@ LL | let r = x;
 LL | || x; //~ ERROR
  | ^^ - use occurs due to use in closure
  | |
- | value used here after move
+ | value used here after partial move
 
 error: aborting due to 9 previous errors
 

src/test/ui/nll/closure-move-spans.stderr

@@ -8,7 +8,7 @@ LL | || x;
  | |
  | value moved into closure here
 LL | let y = x; //~ ERROR
- | ^ value used here after move
+ | ^ value used here after partial move
 
 error[E0382]: borrow of moved value: `x`
  --> $DIR/closure-move-spans.rs:12:13
@@ -20,7 +20,7 @@ LL | || x;
  | |
  | value moved into closure here
 LL | let y = &x; //~ ERROR
- | ^^ value borrowed here after move
+ | ^^ value borrowed here after partial move
 
 error[E0382]: borrow of moved value: `x`
  --> $DIR/closure-move-spans.rs:17:13
@@ -32,7 +32,7 @@ LL | || x;
  | |
  | value moved into closure here
 LL | let y = &mut x; //~ ERROR
- | ^^^^^^ value borrowed here after move
+ | ^^^^^^ value borrowed here after partial move
 
 error: aborting due to 3 previous errors
 

src/test/ui/nll/decl-macro-illegal-copy.stderr

@@ -5,7 +5,7 @@ LL | $wrapper.inner
  | -------------- value moved here
 ...
 LL | wrapper.inner,
- | ^^^^^^^^^^^^^ value used here after move
+ | ^^^^^^^^^^^^^ value used here after partial move
  |
  = note: move occurs because `wrapper.inner` has type `NonCopy`, which does not implement the `Copy` trait
 

src/test/ui/nll/issue-21232-partial-init-and-erroneous-use.stderr

@@ -18,7 +18,7 @@ LL | let mut d = D { x: 0, s: S{ y: 0, z: 0 } };
 LL | drop(d);
  | - value moved here
 LL | d.x = 10;
- | ^^^^^^^^ value assigned here after move
+ | ^^^^^^^^ value assigned here after partial move
 
 error[E0381]: assign to part of possibly uninitialized variable: `d`
  --> $DIR/issue-21232-partial-init-and-erroneous-use.rs:49:5

src/test/ui/nll/issue-21232-partial-init-and-use.stderr

@@ -18,7 +18,7 @@ LL | let mut s: S<B> = S::new(); drop(s);
  | |
  | move occurs because `s` has type `S<std::boxed::Box<u32>>`, which does not implement the `Copy` trait
 LL | s.x = 10; s.y = Box::new(20);
- | ^^^^^^^^ value partially assigned here after move
+ | ^^^^^^^^ value partially assigned here after partial move
 
 error[E0382]: assign to part of moved value: `t`
  --> $DIR/issue-21232-partial-init-and-use.rs:120:5
@@ -28,7 +28,7 @@ LL | let mut t: T = (0, Box::new(0)); drop(t);
  | |
  | move occurs because `t` has type `(u32, std::boxed::Box<u32>)`, which does not implement the `Copy` trait
 LL | t.0 = 10; t.1 = Box::new(20);
- | ^^^^^^^^ value partially assigned here after move
+ | ^^^^^^^^ value partially assigned here after partial move
 
 error[E0381]: assign to part of possibly uninitialized variable: `s`
  --> $DIR/issue-21232-partial-init-and-use.rs:127:5
@@ -50,7 +50,7 @@ LL | let mut s: S<B> = S::new(); drop(s);
  | |
  | move occurs because `s` has type `S<std::boxed::Box<u32>>`, which does not implement the `Copy` trait
 LL | s.x = 10;
- | ^^^^^^^^ value partially assigned here after move
+ | ^^^^^^^^ value partially assigned here after partial move
 
 error[E0382]: assign to part of moved value: `t`
  --> $DIR/issue-21232-partial-init-and-use.rs:148:5
@@ -60,7 +60,7 @@ LL | let mut t: T = (0, Box::new(0)); drop(t);
  | |
  | move occurs because `t` has type `(u32, std::boxed::Box<u32>)`, which does not implement the `Copy` trait
 LL | t.0 = 10;
- | ^^^^^^^^ value partially assigned here after move
+ | ^^^^^^^^ value partially assigned here after partial move
 
 error[E0381]: assign to part of possibly uninitialized variable: `s`
  --> $DIR/issue-21232-partial-init-and-use.rs:155:5
@@ -159,7 +159,7 @@ LL | match c {
 LL | c2 => {
  | -- value moved here
 LL | c.0 = 2; //~ ERROR assign to part of moved value
- | ^^^^^^^ value partially assigned here after move
+ | ^^^^^^^ value partially assigned here after partial move
 
 error[E0382]: assign to part of moved value: `c`
  --> $DIR/issue-21232-partial-init-and-use.rs:269:13

src/test/ui/nll/move-subpaths-moves-root.stderr

@@ -4,7 +4,7 @@ error[E0382]: use of moved value: `x`
 LL | drop(x.0);
  | --- value moved here
 LL | drop(x); //~ ERROR use of moved value
- | ^ value used here after move
+ | ^ value used here after partial move
  |
  = note: move occurs because `x.0` has type `std::vec::Vec<i32>`, which does not implement the `Copy` trait
 

src/test/ui/try-block/try-block-bad-lifetime.stderr

@@ -32,7 +32,7 @@ LL | Err(k) ?;
  | - value moved here
 ...
 LL | ::std::mem::drop(k); //~ ERROR use of moved value: `k`
- | ^ value used here after move
+ | ^ value used here after partial move
 
 error[E0506]: cannot assign to `i` because it is borrowed
  --> $DIR/try-block-bad-lifetime.rs:32:9

src/test/ui/try-block/try-block-maybe-bad-lifetime.stderr

@@ -20,7 +20,7 @@ LL | ::std::mem::drop(x);
  | - value moved here
 LL | };
 LL | println!("{}", x); //~ ERROR borrow of moved value: `x`
- | ^ value borrowed here after move
+ | ^ value borrowed here after partial move
 
 error[E0506]: cannot assign to `i` because it is borrowed
  --> $DIR/try-block-maybe-bad-lifetime.rs:40:9