Rollup merge of rust-lang#51057 - pnkfelix:issue-51025-make-ui-tests-…

…robust-wrt-nll, r=nikomatsakis

make ui tests robust with respect to NLL

This PR revises the `ui` tests that I could quickly identify that:
 1. previously had successful compilations under non-lexical lifetimes (NLL) because they assumed lexical lifetimes, but
 2. such assumption of lexical lifetimes was actually not necessarily part of the spirit of the original issue/bug we want to witness.

In many cases, this is simply a matter of adding a use of a borrow so that it gets extended long enough to observe a conflict.

(In some cases the revision was more subtle, such as adding a destructor, or revising the order of declaration of some variables.)

----

With these test revisions in place, I subsequently updated the expected stderr output under the NLL compiletest mode. So now we should get even more testing of NLL than we were before.

Fix rust-lang#51025

src/test/ui/borrowck/borrowck-report-with-custom-diagnostic.nll.stderr

@@ -1,14 +1,40 @@
-error: compilation successful
- --> $DIR/borrowck-report-with-custom-diagnostic.rs:12:1
+error[E0502]: cannot borrow `x` as immutable because it is also borrowed as mutable
+ --> $DIR/borrowck-report-with-custom-diagnostic.rs:17:13
  |
-LL | / fn main() { #![rustc_error] // rust-lang/rust#49855
-LL | | // Original borrow ends at end of function
-LL | |  let mut x = 1;
-LL | |  let y = &mut x;
-... |
-LL | | //~^ immutable borrow occurs here
-LL | | }
- | |_^
+LL |  let y = &mut x;
+ |  ------ mutable borrow occurs here
+LL | //~^ mutable borrow occurs here
+LL | let z = &x; //~ ERROR cannot borrow
+ | ^^ immutable borrow occurs here
+...
+LL |  y.use_mut();
+ |  - borrow later used here
 
-error: aborting due to previous error
+error[E0502]: cannot borrow `x` as mutable because it is also borrowed as immutable
+ --> $DIR/borrowck-report-with-custom-diagnostic.rs:30:21
+ |
+LL | let y = &x;
+ | -- immutable borrow occurs here
+LL | //~^ immutable borrow occurs here
+LL | let z = &mut x; //~ ERROR cannot borrow
+ | ^^^^^^ mutable borrow occurs here
+...
+LL | y.use_ref();
+ | - borrow later used here
+
+error[E0499]: cannot borrow `x` as mutable more than once at a time
+ --> $DIR/borrowck-report-with-custom-diagnostic.rs:45:17
+ |
+LL | let y = &mut x;
+ | ------ first mutable borrow occurs here
+LL | //~^ first mutable borrow occurs here
+LL | let z = &mut x; //~ ERROR cannot borrow
+ | ^^^^^^ second mutable borrow occurs here
+...
+LL | y.use_mut();
+ | - borrow later used here
+
+error: aborting due to 3 previous errors
 
+Some errors occurred: E0499, E0502.
+For more information about an error, try `rustc --explain E0499`.

src/test/ui/borrowck/borrowck-report-with-custom-diagnostic.rs

@@ -16,6 +16,8 @@ fn main() { #![rustc_error] // rust-lang/rust#49855
  //~^ mutable borrow occurs here
  let z = &x; //~ ERROR cannot borrow
  //~^ immutable borrow occurs here
+ z.use_ref();
+ y.use_mut();
 }
 
 fn foo() {
@@ -27,6 +29,8 @@ fn foo() {
  //~^ immutable borrow occurs here
  let z = &mut x; //~ ERROR cannot borrow
  //~^ mutable borrow occurs here
+ z.use_mut();
+ y.use_ref();
  }
  false => ()
  }
@@ -40,5 +44,10 @@ fn bar() {
  //~^ first mutable borrow occurs here
  let z = &mut x; //~ ERROR cannot borrow
  //~^ second mutable borrow occurs here
+ z.use_mut();
+ y.use_mut();
  };
 }
+
+trait Fake { fn use_mut(&mut self) { } fn use_ref(&self) { } }
+impl<T> Fake for T { }

src/test/ui/borrowck/borrowck-report-with-custom-diagnostic.stderr

@@ -6,31 +6,31 @@ LL | let y = &mut x;
 LL | //~^ mutable borrow occurs here
 LL | let z = &x; //~ ERROR cannot borrow
  | ^ immutable borrow occurs here
-LL | //~^ immutable borrow occurs here
+...
 LL | }
  | - mutable borrow ends here
 
 error[E0502]: cannot borrow `x` as mutable because it is also borrowed as immutable
- --> $DIR/borrowck-report-with-custom-diagnostic.rs:28:26
+ --> $DIR/borrowck-report-with-custom-diagnostic.rs:30:26
  |
 LL | let y = &x;
  | - immutable borrow occurs here
 LL | //~^ immutable borrow occurs here
 LL | let z = &mut x; //~ ERROR cannot borrow
  | ^ mutable borrow occurs here
-LL | //~^ mutable borrow occurs here
+...
 LL | }
  | - immutable borrow ends here
 
 error[E0499]: cannot borrow `x` as mutable more than once at a time
- --> $DIR/borrowck-report-with-custom-diagnostic.rs:41:22
+ --> $DIR/borrowck-report-with-custom-diagnostic.rs:45:22
  |
 LL | let y = &mut x;
  | - first mutable borrow occurs here
 LL | //~^ first mutable borrow occurs here
 LL | let z = &mut x; //~ ERROR cannot borrow
  | ^ second mutable borrow occurs here
-LL | //~^ second mutable borrow occurs here
+...
 LL | };
  | - first borrow ends here
 

src/test/ui/borrowck/mut-borrow-outside-loop.nll.stderr

@@ -1,14 +1,24 @@
-error: compilation successful
- --> $DIR/mut-borrow-outside-loop.rs:13:1
+error[E0499]: cannot borrow `void` as mutable more than once at a time
+ --> $DIR/mut-borrow-outside-loop.rs:17:18
  |
-LL | / fn main() { #![rustc_error] // rust-lang/rust#49855
-LL | | let mut void = ();
-LL | |
-LL | | let first = &mut void;
-... |
-LL | | }
-LL | | }
- | |_^
+LL | let first = &mut void;
+ | --------- first mutable borrow occurs here
+LL | let second = &mut void; //~ ERROR cannot borrow
+ | ^^^^^^^^^ second mutable borrow occurs here
+LL | first.use_mut();
+ | ----- borrow later used here
 
-error: aborting due to previous error
+error[E0499]: cannot borrow `inner_void` as mutable more than once at a time
+ --> $DIR/mut-borrow-outside-loop.rs:25:28
+ |
+LL | let inner_first = &mut inner_void;
+ | --------------- first mutable borrow occurs here
+LL | let inner_second = &mut inner_void; //~ ERROR cannot borrow
+ | ^^^^^^^^^^^^^^^ second mutable borrow occurs here
+LL | inner_second.use_mut();
+LL | inner_first.use_mut();
+ | ----------- borrow later used here
+
+error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0499`.

src/test/ui/borrowck/mut-borrow-outside-loop.rs

@@ -15,12 +15,18 @@ fn main() { #![rustc_error] // rust-lang/rust#49855
 
  let first = &mut void;
  let second = &mut void; //~ ERROR cannot borrow
+ first.use_mut();
+ second.use_mut();
 
  loop {
  let mut inner_void = ();
 
  let inner_first = &mut inner_void;
  let inner_second = &mut inner_void; //~ ERROR cannot borrow
+ inner_second.use_mut();
+ inner_first.use_mut();
  }
 }
 
+trait Fake { fn use_mut(&mut self) { } fn use_ref(&self) { } }
+impl<T> Fake for T { }

src/test/ui/borrowck/mut-borrow-outside-loop.stderr

@@ -10,12 +10,13 @@ LL | }
  | - first borrow ends here
 
 error[E0499]: cannot borrow `inner_void` as mutable more than once at a time
- --> $DIR/mut-borrow-outside-loop.rs:23:33
+ --> $DIR/mut-borrow-outside-loop.rs:25:33
  |
 LL | let inner_first = &mut inner_void;
  | ---------- first mutable borrow occurs here
 LL | let inner_second = &mut inner_void; //~ ERROR cannot borrow
  | ^^^^^^^^^^ second mutable borrow occurs here
+...
 LL | }
  | - first borrow ends here
 

src/test/ui/codemap_tests/issue-11715.nll.stderr

@@ -1,12 +1,14 @@
-error: compilation successful
- --> $DIR/issue-11715.rs:97:1
+error[E0499]: cannot borrow `x` as mutable more than once at a time
+ --> $DIR/issue-11715.rs:100:13
  |
-LL | / fn main() { #![rustc_error] // rust-lang/rust#49855
-LL | | let mut x = "foo";
-LL | | let y = &mut x;
-LL | | let z = &mut x; //~ ERROR cannot borrow
-LL | | }
- | |_^
+LL | let y = &mut x;
+ | ------ first mutable borrow occurs here
+LL | let z = &mut x; //~ ERROR cannot borrow
+ | ^^^^^^ second mutable borrow occurs here
+LL | z.use_mut();
+LL | y.use_mut();
+ | - borrow later used here
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0499`.

src/test/ui/codemap_tests/issue-11715.rs

@@ -98,4 +98,9 @@ fn main() { #![rustc_error] // rust-lang/rust#49855
  let mut x = "foo";
  let y = &mut x;
  let z = &mut x; //~ ERROR cannot borrow
+ z.use_mut();
+ y.use_mut();
 }
+
+trait Fake { fn use_mut(&mut self) { } fn use_ref(&self) { } }
+impl<T> Fake for T { }

src/test/ui/codemap_tests/issue-11715.stderr

@@ -5,6 +5,7 @@ LL | let y = &mut x;
  | - first mutable borrow occurs here
 LL | let z = &mut x; //~ ERROR cannot borrow
  | ^ second mutable borrow occurs here
+...
 LL | }
  | - first borrow ends here
 

src/test/ui/dropck/dropck-eyepatch-extern-crate.nll.stderr

@@ -1,14 +1,15 @@
-error: compilation successful
- --> $DIR/dropck-eyepatch-extern-crate.rs:27:1
+error[E0597]: `c_shortest` does not live long enough
+ --> $DIR/dropck-eyepatch-extern-crate.rs:47:19
  |
-LL | / fn main() { #![rustc_error] // rust-lang/rust#49855
-LL | | use std::cell::Cell;
-LL | | let c_long;
-LL | | let (c, mut dt, mut dr, mut pt, mut pr, st, sr)
-... |
-LL | | println!("{:?}", (dt.0, dr.0, pt.0, pr.0, st.0, sr.0));
-LL | | }
- | |_^
+LL |  dt = Dt("dt", &c_shortest);
+ |  ^^^^^^^^^^^ borrowed value does not live long enough
+...
+LL | }
+ | -
+ | |
+ | borrowed value only lives until here
+ | borrow later used here, when `dt` is dropped
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0597`.

src/test/ui/dropck/dropck-eyepatch-extern-crate.rs

@@ -27,33 +27,41 @@ use other::{Dt,Dr,Pt,Pr,St,Sr};
 fn main() { #![rustc_error] // rust-lang/rust#49855
  use std::cell::Cell;
  let c_long;
- let (c, mut dt, mut dr, mut pt, mut pr, st, sr)
- : (Cell<_>, Dt<_>, Dr<_>, Pt<_, _>, Pr<_>, St<_>, Sr<_>);
+ let (c, mut dt, mut dr, mut pt, mut pr, st, sr, c_shortest)
+ : (Cell<_>, Dt<_>, Dr<_>, Pt<_, _>, Pr<_>, St<_>, Sr<_>, Cell<_>);
  c_long = Cell::new(1);
  c = Cell::new(1);
+ c_shortest = Cell::new(1);
 
  // No error: sufficiently long-lived state can be referenced in dtors
  dt = Dt("dt", &c_long);
  dr = Dr("dr", &c_long);
+
  // Error: destructor order imprecisely modelled
  dt = Dt("dt", &c);
  //~^ ERROR `c` does not live long enough
  dr = Dr("dr", &c);
  //~^ ERROR `c` does not live long enough
 
+ // Error: `c_shortest` dies too soon for the references in dtors to be valid.
+ dt = Dt("dt", &c_shortest);
+ //~^ ERROR `c_shortest` does not live long enough
+ dr = Dr("dr", &c_shortest);
+ //~^ ERROR `c_shortest` does not live long enough
+
  // No error: Drop impl asserts .1 (A and &'a _) are not accessed
- pt = Pt("pt", &c, &c_long);
- pr = Pr("pr", &c, &c_long);
+ pt = Pt("pt", &c_shortest, &c_long);
+ pr = Pr("pr", &c_shortest, &c_long);
 
  // Error: Drop impl's assertion does not apply to `B` nor `&'b _`
- pt = Pt("pt", &c_long, &c);
- //~^ ERROR `c` does not live long enough
- pr = Pr("pr", &c_long, &c);
- //~^ ERROR `c` does not live long enough
+ pt = Pt("pt", &c_long, &c_shortest);
+ //~^ ERROR `c_shortest` does not live long enough
+ pr = Pr("pr", &c_long, &c_shortest);
+ //~^ ERROR `c_shortest` does not live long enough
 
  // No error: St and Sr have no destructor.
- st = St("st", &c);
- sr = Sr("sr", &c);
+ st = St("st", &c_shortest);
+ sr = Sr("sr", &c_shortest);
 
  println!("{:?}", (dt.0, dr.0, pt.0, pr.0, st.0, sr.0));
 }

src/test/ui/dropck/dropck-eyepatch-extern-crate.stderr

@@ -1,5 +1,5 @@
 error[E0597]: `c` does not live long enough
- --> $DIR/dropck-eyepatch-extern-crate.rs:39:20
+ --> $DIR/dropck-eyepatch-extern-crate.rs:41:20
  |
 LL | dt = Dt("dt", &c);
  | ^ borrowed value does not live long enough
@@ -10,7 +10,7 @@ LL | }
  = note: values in a scope are dropped in the opposite order they are created
 
 error[E0597]: `c` does not live long enough
- --> $DIR/dropck-eyepatch-extern-crate.rs:41:20
+ --> $DIR/dropck-eyepatch-extern-crate.rs:43:20
  |
 LL | dr = Dr("dr", &c);
  | ^ borrowed value does not live long enough
@@ -20,28 +20,50 @@ LL | }
  |
  = note: values in a scope are dropped in the opposite order they are created
 
-error[E0597]: `c` does not live long enough
- --> $DIR/dropck-eyepatch-extern-crate.rs:49:29
+error[E0597]: `c_shortest` does not live long enough
+ --> $DIR/dropck-eyepatch-extern-crate.rs:47:20
  |
-LL | pt = Pt("pt", &c_long, &c);
- |  ^ borrowed value does not live long enough
+LL | dt = Dt("dt", &c_shortest);
+ | ^^^^^^^^^^ borrowed value does not live long enough
 ...
 LL | }
- | - `c` dropped here while still borrowed
+ | - `c_shortest` dropped here while still borrowed
  |
  = note: values in a scope are dropped in the opposite order they are created
 
-error[E0597]: `c` does not live long enough
- --> $DIR/dropck-eyepatch-extern-crate.rs:51:29
+error[E0597]: `c_shortest` does not live long enough
+ --> $DIR/dropck-eyepatch-extern-crate.rs:49:20
  |
-LL | pr = Pr("pr", &c_long, &c);
- |  ^ borrowed value does not live long enough
+LL | dr = Dr("dr", &c_shortest);
+ | ^^^^^^^^^^ borrowed value does not live long enough
 ...
 LL | }
- | - `c` dropped here while still borrowed
+ | - `c_shortest` dropped here while still borrowed
+ |
+ = note: values in a scope are dropped in the opposite order they are created
+
+error[E0597]: `c_shortest` does not live long enough
+ --> $DIR/dropck-eyepatch-extern-crate.rs:57:29
+ |
+LL | pt = Pt("pt", &c_long, &c_shortest);
+ | ^^^^^^^^^^ borrowed value does not live long enough
+...
+LL | }
+ | - `c_shortest` dropped here while still borrowed
+ |
+ = note: values in a scope are dropped in the opposite order they are created
+
+error[E0597]: `c_shortest` does not live long enough
+ --> $DIR/dropck-eyepatch-extern-crate.rs:59:29
+ |
+LL | pr = Pr("pr", &c_long, &c_shortest);
+ | ^^^^^^^^^^ borrowed value does not live long enough
+...
+LL | }
+ | - `c_shortest` dropped here while still borrowed
  |
  = note: values in a scope are dropped in the opposite order they are created
 
-error: aborting due to 4 previous errors
+error: aborting due to 6 previous errors
 
 For more information about this error, try `rustc --explain E0597`.