Use better spans for dummy accesses used in matches

src/librustc_mir/build/matches/mod.rs

@@ -63,13 +63,13 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
         // injects a borrow of the matched input, which should have the same effect
         // as eddyb's hack. Once NLL is the default, we can remove the hack.
 
-        let dummy_source_info = self.source_info(span);
+        let dummy_source_info = self.source_info(discriminant_span);
         let dummy_access = Rvalue::Discriminant(discriminant_place.clone());
         let dummy_ty = dummy_access.ty(&self.local_decls, tcx);
         let dummy_temp = self.temp(dummy_ty, dummy_source_info.span);
         self.cfg.push_assign(block, dummy_source_info, &dummy_temp, dummy_access);
 
-        let source_info = self.source_info(span);
+        let source_info = self.source_info(discriminant_span);
         let borrowed_input_temp = if tcx.generate_borrow_of_any_match_input() {
             // The region is unknown at this point; we rely on NLL
             // inference to find an appropriate one. Therefore you can
@@ -134,9 +134,9 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                         // This should ensure that you cannot change
                         // the variant for an enum while you are in
                         // the midst of matching on it.
-
+                        let pattern_source_info = self.source_info(pattern.span);
                         self.cfg.push(*pre_binding_block, Statement {
-                            source_info,
+                            source_info: pattern_source_info,
                             kind: StatementKind::ReadForMatch(borrow_temp.clone()),
                         });
                     }

src/test/ui/borrowck/issue-41962.stderr

@@ -17,26 +17,22 @@ LL |         if let Some(thing) = maybe {
    = note: move occurs because the value has type `std::vec::Vec<bool>`, which does not implement the `Copy` trait
 
 error[E0382]: use of moved value: `maybe` (Mir)
-  --> $DIR/issue-41962.rs:17:9
+  --> $DIR/issue-41962.rs:17:30
    |
-LL |           if let Some(thing) = maybe {
-   |           ^           ----- value moved here
-   |  _________|
-   | |
-LL | |         }
-   | |_________^ value used here after move
+LL |         if let Some(thing) = maybe {
+   |                     -----    ^^^^^ value used here after move
+   |                     |
+   |                     value moved here
    |
    = note: move occurs because value has type `std::vec::Vec<bool>`, which does not implement the `Copy` trait
 
 error[E0382]: borrow of moved value: `maybe` (Mir)
-  --> $DIR/issue-41962.rs:17:9
+  --> $DIR/issue-41962.rs:17:30
    |
-LL |           if let Some(thing) = maybe {
-   |           ^           ----- value moved here
-   |  _________|
-   | |
-LL | |         }
-   | |_________^ value borrowed here after move
+LL |         if let Some(thing) = maybe {
+   |                     -----    ^^^^^ value borrowed here after move
+   |                     |
+   |                     value moved here
    |
    = note: move occurs because value has type `std::vec::Vec<bool>`, which does not implement the `Copy` trait
 

src/test/ui/issue-17385.nll.stderr

@@ -1,26 +1,20 @@
 error[E0382]: use of moved value: `foo`
-  --> $DIR/issue-17385.rs:28:5
+  --> $DIR/issue-17385.rs:28:11
    |
-LL |       drop(foo);
-   |            --- value moved here
-LL | /     match foo { //~ ERROR use of moved value
-LL | |         X(1) => (),
-LL | |         _ => unreachable!()
-LL | |     }
-   | |_____^ value used here after move
+LL |     drop(foo);
+   |          --- value moved here
+LL |     match foo { //~ ERROR use of moved value
+   |           ^^^ value used here after move
    |
    = note: move occurs because `foo` has type `X`, which does not implement the `Copy` trait
 
 error[E0382]: borrow of moved value: `foo`
-  --> $DIR/issue-17385.rs:28:5
+  --> $DIR/issue-17385.rs:28:11
    |
-LL |       drop(foo);
-   |            --- value moved here
-LL | /     match foo { //~ ERROR use of moved value
-LL | |         X(1) => (),
-LL | |         _ => unreachable!()
-LL | |     }
-   | |_____^ value borrowed here after move
+LL |     drop(foo);
+   |          --- value moved here
+LL |     match foo { //~ ERROR use of moved value
+   |           ^^^ value borrowed here after move
    |
    = note: move occurs because `foo` has type `X`, which does not implement the `Copy` trait
 
@@ -36,28 +30,22 @@ LL |         X(1) => (),
    = note: move occurs because `foo` has type `X`, which does not implement the `Copy` trait
 
 error[E0382]: use of moved value: `e`
-  --> $DIR/issue-17385.rs:35:5
+  --> $DIR/issue-17385.rs:35:11
    |
-LL |       drop(e);
-   |            - value moved here
-LL | /     match e { //~ ERROR use of moved value
-LL | |         Enum::Variant1 => unreachable!(),
-LL | |         Enum::Variant2 => ()
-LL | |     }
-   | |_____^ value used here after move
+LL |     drop(e);
+   |          - value moved here
+LL |     match e { //~ ERROR use of moved value
+   |           ^ value used here after move
    |
    = note: move occurs because `e` has type `Enum`, which does not implement the `Copy` trait
 
 error[E0382]: borrow of moved value: `e`
-  --> $DIR/issue-17385.rs:35:5
+  --> $DIR/issue-17385.rs:35:11
    |
-LL |       drop(e);
-   |            - value moved here
-LL | /     match e { //~ ERROR use of moved value
-LL | |         Enum::Variant1 => unreachable!(),
-LL | |         Enum::Variant2 => ()
-LL | |     }
-   | |_____^ value borrowed here after move
+LL |     drop(e);
+   |          - value moved here
+LL |     match e { //~ ERROR use of moved value
+   |           ^ value borrowed here after move
    |
    = note: move occurs because `e` has type `Enum`, which does not implement the `Copy` trait
 

src/test/ui/issue-27282-move-match-input-into-guard.stderr

@@ -1,21 +1,14 @@
 error[E0505]: cannot move out of `b` because it is borrowed
   --> $DIR/issue-27282-move-match-input-into-guard.rs:26:16
    |
-LL |        match b {
-   |   _____-
-   |  |_____|
-   | ||
-LL | ||         &mut false => {},
-LL | ||         _ if { (|| { let bar = b; *bar = false; })();
-   | ||                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ move out of `b` occurs here
-LL | ||                      //~^ ERROR cannot move out of `b` because it is borrowed [E0505]
-...  ||
-LL | ||         _ => panic!("surely we could never get here, since rustc warns it is unreachable."),
-LL | ||     }
-   | ||     -
-   | ||_____|
-   | |______borrow of `b` occurs here
-   |        borrow later used here
+LL |     match b {
+   |           - borrow of `b` occurs here
+LL |         &mut false => {},
+LL |         _ if { (|| { let bar = b; *bar = false; })();
+   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ move out of `b` occurs here
+...
+LL |         &mut true => { println!("You might think we should get here"); },
+   |         --------- borrow later used here
 
 error[E0382]: use of moved value: `*b`
   --> $DIR/issue-27282-move-match-input-into-guard.rs:29:14

src/test/ui/issue-27282-mutate-before-diverging-arm-1.stderr

@@ -1,24 +1,16 @@
 error[E0500]: closure requires unique access to `x` but it is already borrowed
   --> $DIR/issue-27282-mutate-before-diverging-arm-1.rs:33:14
    |
-LL |        match x {
-   |   _____-
-   |  |_____|
-   | ||
-LL | ||         &mut None => panic!("unreachable"),
-LL | ||         &mut Some(&_) if {
-LL | ||             // ForceFnOnce needed to exploit #27282
-LL | ||             (|| { *x = None; drop(force_fn_once); })();
-   | ||              ^^    - borrow occurs due to use of `x` in closure
-   | ||              |
-   | ||              closure construction occurs here
-...  ||
-LL | ||         _ => panic!("unreachable"),
-LL | ||     }
-   | ||     -
-   | ||_____|
-   | |______borrow occurs here
-   |        borrow later used here
+LL |     match x {
+   |           - borrow occurs here
+...
+LL |             (|| { *x = None; drop(force_fn_once); })();
+   |              ^^    - borrow occurs due to use of `x` in closure
+   |              |
+   |              closure construction occurs here
+...
+LL |         &mut Some(&a) if { // this binds to garbage if we've corrupted discriminant
+   |         ------------- borrow later used here
 
 error: aborting due to previous error
 

src/test/ui/issue-27282-mutate-before-diverging-arm-2.stderr

@@ -1,25 +1,16 @@
 error[E0500]: closure requires unique access to `x` but it is already borrowed
   --> $DIR/issue-27282-mutate-before-diverging-arm-2.rs:38:18
    |
-LL |        match x {
-   |   _____-
-   |  |_____|
-   | ||
-LL | ||         &mut None => panic!("unreachable"),
-LL | ||         &mut Some(&_)
-LL | ||             if {
-LL | ||                 // ForceFnOnce needed to exploit #27282
-LL | ||                 (|| { *x = None; drop(force_fn_once); })();
-   | ||                  ^^    - borrow occurs due to use of `x` in closure
-   | ||                  |
-   | ||                  closure construction occurs here
-...  ||
-LL | ||         _ => panic!("unreachable"),
-LL | ||     }
-   | ||     -
-   | ||_____|
-   | |______borrow occurs here
-   |        borrow later used here
+LL |     match x {
+   |           - borrow occurs here
+...
+LL |                 (|| { *x = None; drop(force_fn_once); })();
+   |                  ^^    - borrow occurs due to use of `x` in closure
+   |                  |
+   |                  closure construction occurs here
+...
+LL |         &mut Some(&2)
+   |         ------------- borrow later used here
 
 error: aborting due to previous error
 

src/test/ui/issue-47412.stderr

@@ -1,16 +1,16 @@
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/issue-47412.rs:21:5
+  --> $DIR/issue-47412.rs:21:11
    |
 LL |     match u.void {}
-   |     ^^^^^^^^^^^^^^^ access to union field
+   |           ^^^^^^ access to union field
    |
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: dereference of raw pointer is unsafe and requires unsafe function or block
-  --> $DIR/issue-47412.rs:27:5
+  --> $DIR/issue-47412.rs:27:11
    |
 LL |     match *ptr {}
-   |     ^^^^^^^^^^^^^ dereference of raw pointer
+   |           ^^^^ dereference of raw pointer
    |
    = note: raw pointers may be NULL, dangling or unaligned; they can violate aliasing rules and cause data races: all of these are undefined behavior
 

src/test/ui/lifetime-errors/ex1-return-one-existing-name-early-bound-in-struct.nll.stderr

@@ -5,18 +5,12 @@ LL |                     other //~ ERROR explicit lifetime
    |                     ^^^^^
 
 error[E0621]: explicit lifetime required in the type of `other`
-  --> $DIR/ex1-return-one-existing-name-early-bound-in-struct.rs:18:9
+  --> $DIR/ex1-return-one-existing-name-early-bound-in-struct.rs:18:15
    |
-LL |       fn bar(&self, other: Foo) -> Foo<'a> {
-   |                     ----- consider changing the type of `other` to `Foo<'a>`
-LL | /         match *self {
-LL | |             Foo::Bar(s) => {
-LL | |                 if s == "test" {
-LL | |                     other //~ ERROR explicit lifetime
-...  |
-LL | |             }
-LL | |         }
-   | |_________^ lifetime `'a` required
+LL |     fn bar(&self, other: Foo) -> Foo<'a> {
+   |                   ----- consider changing the type of `other` to `Foo<'a>`
+LL |         match *self {
+   |               ^^^^^ lifetime `'a` required
 
 error: aborting due to previous error
 

src/test/ui/nll/borrowed-match-issue-45045.stderr

@@ -1,17 +1,14 @@
 error[E0503]: cannot use `e` because it was mutably borrowed
-  --> $DIR/borrowed-match-issue-45045.rs:24:5
+  --> $DIR/borrowed-match-issue-45045.rs:24:11
    |
-LL |       let f = &mut e;
-   |               ------ borrow of `e` occurs here
-LL |       let g = f;
-LL | /     match e { //~ cannot use `e` because it was mutably borrowed [E0503]
-LL | |         Xyz::A => println!("a"),
-LL | |         //~^ cannot use `e` because it was mutably borrowed [E0503]
-LL | |         Xyz::B => println!("b"),
-LL | |     };
-   | |_____^ use of borrowed `e`
-LL |       *g = Xyz::B;
-   |       ----------- borrow later used here
+LL |     let f = &mut e;
+   |             ------ borrow of `e` occurs here
+LL |     let g = f;
+LL |     match e { //~ cannot use `e` because it was mutably borrowed [E0503]
+   |           ^ use of borrowed `e`
+...
+LL |     *g = Xyz::B;
+   |     ----------- borrow later used here
 
 error[E0503]: cannot use `e` because it was mutably borrowed
   --> $DIR/borrowed-match-issue-45045.rs:25:9

src/test/ui/span/issue-40157.nll.stderr

@@ -2,11 +2,11 @@ error[E0597]: `foo` does not live long enough
   --> $DIR/issue-40157.rs:12:53
    |
 LL |     {println!("{:?}", match { let foo = vec![1, 2]; foo.get(1) } { x => x });}
-   |                       ------------------------------^^^--------------------
-   |                       |                             |          |
-   |                       |                             |          `foo` dropped here while still borrowed
-   |                       |                             borrowed value does not live long enough
-   |                       borrow later used here
+   |                             ------------------------^^^---------
+   |                             |                       |          |
+   |                             |                       |          `foo` dropped here while still borrowed
+   |                             |                       borrowed value does not live long enough
+   |                             borrow later used here
 
 error: aborting due to previous error