add explicit revisions to polonius tests

The blessed expectations were recently removed because they were only
checked via the compare-mode. This switches to explicit revisions to
ensure it doesn't happen again.

- `assignment-to-differing-field`
- `polonius-smoke-test`
- `subset-relations`

tests/ui/nll/polonius/assignment-to-differing-field.stderr → tests/ui/nll/polonius/assignment-to-differing-field.legacy.stderr

@@ -1,5 +1,5 @@
 error[E0499]: cannot borrow `list.0.value` as mutable more than once at a time
-  --> $DIR/assignment-to-differing-field.rs:20:21
+  --> $DIR/assignment-to-differing-field.rs:23:21
    |
 LL | fn assignment_to_field_projection<'a, T>(
    |                                   -- lifetime `'a` defined here
@@ -11,7 +11,7 @@ LL |             return result;
    |                    ------ returning this value requires that `list.0.value` is borrowed for `'a`
 
 error[E0499]: cannot borrow `list.0.next` as mutable more than once at a time
-  --> $DIR/assignment-to-differing-field.rs:23:26
+  --> $DIR/assignment-to-differing-field.rs:26:26
    |
 LL | fn assignment_to_field_projection<'a, T>(
    |                                   -- lifetime `'a` defined here
@@ -23,7 +23,7 @@ LL |             list.1 = n;
    |             ---------- assignment requires that `list.0.next` is borrowed for `'a`
 
 error[E0499]: cannot borrow `list.0.0.0.0.0.value` as mutable more than once at a time
-  --> $DIR/assignment-to-differing-field.rs:37:21
+  --> $DIR/assignment-to-differing-field.rs:40:21
    |
 LL | fn assignment_through_projection_chain<'a, T>(
    |                                        -- lifetime `'a` defined here
@@ -35,7 +35,7 @@ LL |             return result;
    |                    ------ returning this value requires that `list.0.0.0.0.0.value` is borrowed for `'a`
 
 error[E0499]: cannot borrow `list.0.0.0.0.0.next` as mutable more than once at a time
-  --> $DIR/assignment-to-differing-field.rs:40:26
+  --> $DIR/assignment-to-differing-field.rs:43:26
    |
 LL | fn assignment_through_projection_chain<'a, T>(
    |                                        -- lifetime `'a` defined here

tests/ui/nll/polonius/assignment-to-differing-field.polonius.stderr

@@ -0,0 +1,51 @@
+error[E0499]: cannot borrow `list.0.value` as mutable more than once at a time
+  --> $DIR/assignment-to-differing-field.rs:23:21
+   |
+LL | fn assignment_to_field_projection<'a, T>(
+   |                                   -- lifetime `'a` defined here
+...
+LL |         result.push(&mut (list.0).value);
+   |                     ^^^^^^^^^^^^^^^^^^^ `list.0.value` was mutably borrowed here in the previous iteration of the loop
+...
+LL |             return result;
+   |                    ------ returning this value requires that `list.0.value` is borrowed for `'a`
+
+error[E0499]: cannot borrow `list.0.next` as mutable more than once at a time
+  --> $DIR/assignment-to-differing-field.rs:26:26
+   |
+LL | fn assignment_to_field_projection<'a, T>(
+   |                                   -- lifetime `'a` defined here
+...
+LL |         if let Some(n) = (list.0).next.as_mut() {
+   |                          ^^^^^^^^^^^^^ `list.0.next` was mutably borrowed here in the previous iteration of the loop
+LL |
+LL |             list.1 = n;
+   |             ---------- assignment requires that `list.0.next` is borrowed for `'a`
+
+error[E0499]: cannot borrow `list.0.0.0.0.0.value` as mutable more than once at a time
+  --> $DIR/assignment-to-differing-field.rs:40:21
+   |
+LL | fn assignment_through_projection_chain<'a, T>(
+   |                                        -- lifetime `'a` defined here
+...
+LL |         result.push(&mut ((((list.0).0).0).0).0.value);
+   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `list.0.0.0.0.0.value` was mutably borrowed here in the previous iteration of the loop
+...
+LL |             return result;
+   |                    ------ returning this value requires that `list.0.0.0.0.0.value` is borrowed for `'a`
+
+error[E0499]: cannot borrow `list.0.0.0.0.0.next` as mutable more than once at a time
+  --> $DIR/assignment-to-differing-field.rs:43:26
+   |
+LL | fn assignment_through_projection_chain<'a, T>(
+   |                                        -- lifetime `'a` defined here
+...
+LL |         if let Some(n) = ((((list.0).0).0).0).0.next.as_mut() {
+   |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^ `list.0.0.0.0.0.next` was mutably borrowed here in the previous iteration of the loop
+LL |
+LL |             *((((list.0).0).0).0).1 = n;
+   |             --------------------------- assignment requires that `list.0.0.0.0.0.next` is borrowed for `'a`
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0499`.

tests/ui/nll/polonius/assignment-to-differing-field.rs

@@ -4,7 +4,10 @@
 // that we do not kill too many borrows. Assignments to the `.1`
 // field projections should leave the borrows on `.0` intact.
 
-//@ compile-flags: -Z polonius
+//@ ignore-compare-mode-polonius (explicit revisions)
+//@ revisions: polonius legacy
+//@ [polonius] compile-flags: -Z polonius=next
+//@ [legacy] compile-flags: -Z polonius=legacy
 
 struct List<T> {
     value: T,

tests/ui/nll/polonius/polonius-smoke-test.stderr → tests/ui/nll/polonius/polonius-smoke-test.legacy.stderr

@@ -1,11 +1,11 @@
 error[E0515]: cannot return reference to local variable `x`
-  --> $DIR/polonius-smoke-test.rs:6:5
+  --> $DIR/polonius-smoke-test.rs:10:5
    |
 LL |     &x
    |     ^^ returns a reference to data owned by the current function
 
 error[E0503]: cannot use `x` because it was mutably borrowed
-  --> $DIR/polonius-smoke-test.rs:12:13
+  --> $DIR/polonius-smoke-test.rs:16:13
    |
 LL |     let y = &mut x;
    |             ------ `x` is borrowed here
@@ -15,7 +15,7 @@ LL |     let w = y;
    |             - borrow later used here
 
 error[E0505]: cannot move out of `x` because it is borrowed
-  --> $DIR/polonius-smoke-test.rs:18:13
+  --> $DIR/polonius-smoke-test.rs:22:13
    |
 LL | pub fn use_while_mut_fr(x: &mut i32) -> &mut i32 {
    |                         -  - let's call the lifetime of this reference `'1`
@@ -35,7 +35,7 @@ LL +     let y = &mut x.clone();
    |
 
 error[E0505]: cannot move out of `s` because it is borrowed
-  --> $DIR/polonius-smoke-test.rs:42:5
+  --> $DIR/polonius-smoke-test.rs:46:5
    |
 LL |     let s = &mut 1;
    |         - binding `s` declared here

tests/ui/nll/polonius/polonius-smoke-test.polonius.stderr

@@ -0,0 +1,59 @@
+error[E0515]: cannot return reference to local variable `x`
+  --> $DIR/polonius-smoke-test.rs:10:5
+   |
+LL |     &x
+   |     ^^ returns a reference to data owned by the current function
+
+error[E0503]: cannot use `x` because it was mutably borrowed
+  --> $DIR/polonius-smoke-test.rs:16:13
+   |
+LL |     let y = &mut x;
+   |             ------ `x` is borrowed here
+LL |     let z = x;
+   |             ^ use of borrowed `x`
+LL |     let w = y;
+   |             - borrow later used here
+
+error[E0505]: cannot move out of `x` because it is borrowed
+  --> $DIR/polonius-smoke-test.rs:22:13
+   |
+LL | pub fn use_while_mut_fr(x: &mut i32) -> &mut i32 {
+   |                         -  - let's call the lifetime of this reference `'1`
+   |                         |
+   |                         binding `x` declared here
+LL |     let y = &mut *x;
+   |             ------- borrow of `*x` occurs here
+LL |     let z = x;
+   |             ^ move out of `x` occurs here
+LL |     y
+   |     - returning this value requires that `*x` is borrowed for `'1`
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL -     let y = &mut *x;
+LL +     let y = &mut x.clone();
+   |
+
+error[E0505]: cannot move out of `s` because it is borrowed
+  --> $DIR/polonius-smoke-test.rs:46:5
+   |
+LL |     let s = &mut 1;
+   |         - binding `s` declared here
+LL |     let r = &mut *s;
+   |             ------- borrow of `*s` occurs here
+LL |     let tmp = foo(&r);
+LL |     s;
+   |     ^ move out of `s` occurs here
+LL |     tmp;
+   |     --- borrow later used here
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL -     let r = &mut *s;
+LL +     let r = &mut s.clone();
+   |
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0503, E0505, E0515.
+For more information about an error, try `rustc --explain E0503`.

tests/ui/nll/polonius/polonius-smoke-test.rs

@@ -1,5 +1,9 @@
-// Check that Polonius borrow check works for simple cases.
-//@ compile-flags: -Z polonius
+// Check that Polonius works for simple cases.
+
+//@ ignore-compare-mode-polonius (explicit revisions)
+//@ revisions: polonius legacy
+//@ [polonius] compile-flags: -Z polonius=next
+//@ [legacy] compile-flags: -Z polonius=legacy
 
 pub fn return_ref_to_local() -> &'static i32 {
     let x = 0;

tests/ui/nll/polonius/subset-relations.stderr → tests/ui/nll/polonius/subset-relations.legacy.stderr

@@ -1,5 +1,5 @@
 error: lifetime may not live long enough
-  --> $DIR/subset-relations.rs:10:5
+  --> $DIR/subset-relations.rs:13:5
    |
 LL | fn missing_subset<'a, 'b>(x: &'a u32, y: &'b u32) -> &'a u32 {
    |                   --  -- lifetime `'b` defined here

tests/ui/nll/polonius/subset-relations.polonius.stderr

@@ -0,0 +1,14 @@
+error: lifetime may not live long enough
+  --> $DIR/subset-relations.rs:13:5
+   |
+LL | fn missing_subset<'a, 'b>(x: &'a u32, y: &'b u32) -> &'a u32 {
+   |                   --  -- lifetime `'b` defined here
+   |                   |
+   |                   lifetime `'a` defined here
+LL |     y
+   |     ^ function was supposed to return data with lifetime `'a` but it is returning data with lifetime `'b`
+   |
+   = help: consider adding the following bound: `'b: 'a`
+
+error: aborting due to 1 previous error
+

tests/ui/nll/polonius/subset-relations.rs

@@ -3,7 +3,10 @@
 // two free regions outlive each other, without any evidence that this
 // relation holds.
 
-//@ compile-flags: -Z polonius
+//@ ignore-compare-mode-polonius (explicit revisions)
+//@ revisions: polonius legacy
+//@ [polonius] compile-flags: -Z polonius=next
+//@ [legacy] compile-flags: -Z polonius=legacy
 
 // returning `y` requires that `'b: 'a`, but it's not known to be true
 fn missing_subset<'a, 'b>(x: &'a u32, y: &'b u32) -> &'a u32 {
@@ -22,7 +25,7 @@ fn implied_bounds_subset<'a, 'b>(x: &'a &'b mut u32) -> &'a u32 {
 
 // `'b: 'a` is declared, and `'a: 'c` is known via implied bounds:
 // `'b: 'c` is therefore known to hold transitively
-fn transitively_valid_subset<'a, 'b: 'a, 'c>(x: &'c &'a u32, y: &'b u32) -> &'c u32  {
+fn transitively_valid_subset<'a, 'b: 'a, 'c>(x: &'c &'a u32, y: &'b u32) -> &'c u32 {
     y
 }