Fix debugger stepping behavior around `match` expressions

Previously, we would set up the source lines for `match` expressions so
that the code generated to perform the test of the scrutinee was matched
to the line of the arm that required the test and then jump from the arm
block to the "next" block was matched to all of the lines in the `match`
expression.

While that makes sense, it has the side effect of causing strange
stepping behavior in debuggers.

I've changed the source information so that all of the generated tests
are sourced to `match {scrutinee}` and the jumps are sourced to the last
line of the block they are inside. This resolves the weird stepping
behavior in all debuggers and resolves some instances of "ambiguous
symbol" errors in WinDbg preventing the user from setting breakpoints at
`match` expressions.

21 files changed, 63 insertions, 65 deletions

diff --git a/src/test/ui/borrowck/borrowck-anon-fields-variant.rs b/src/test/ui/borrowck/borrowck-anon-fields-variant.rs
index cecc278e193..6e63de9136c 100644
--- a/src/test/ui/borrowck/borrowck-anon-fields-variant.rs
+++ b/src/test/ui/borrowck/borrowck-anon-fields-variant.rs
@@ -14,8 +14,8 @@ fn distinct_variant() {
     // also used for the discriminant of `Foo`, which it would be if `a` was a
     // reference.
     let b = match y {
-      Foo::Y(_, ref mut b) => b,
       //~^ ERROR cannot use `y`
+      Foo::Y(_, ref mut b) => b,
       Foo::X => panic!()
     };
 
@@ -32,8 +32,9 @@ fn same_variant() {
     };
 
     let b = match y {
-      Foo::Y(ref mut b, _) => b, //~ ERROR cannot use `y`
-      //~| ERROR cannot borrow `y.0` as mutable
+      //~^ ERROR cannot use `y`
+      Foo::Y(ref mut b, _) => b,
+      //~^ ERROR cannot borrow `y.0` as mutable
       Foo::X => panic!()
     };
 
diff --git a/src/test/ui/borrowck/borrowck-anon-fields-variant.stderr b/src/test/ui/borrowck/borrowck-anon-fields-variant.stderr
index 2caeed1bd44..98f6f00a7d4 100644
--- a/src/test/ui/borrowck/borrowck-anon-fields-variant.stderr
+++ b/src/test/ui/borrowck/borrowck-anon-fields-variant.stderr
@@ -1,29 +1,29 @@
 error[E0503]: cannot use `y` because it was mutably borrowed
-  --> $DIR/borrowck-anon-fields-variant.rs:17:7
+  --> $DIR/borrowck-anon-fields-variant.rs:16:19
    |
 LL |       Foo::Y(ref mut a, _) => a,
    |              --------- borrow of `y.0` occurs here
 ...
-LL |       Foo::Y(_, ref mut b) => b,
-   |       ^^^^^^^^^^^^^^^^^^^^ use of borrowed `y.0`
+LL |     let b = match y {
+   |                   ^ use of borrowed `y.0`
 ...
 LL |     *a += 1;
    |     ------- borrow later used here
 
 error[E0503]: cannot use `y` because it was mutably borrowed
-  --> $DIR/borrowck-anon-fields-variant.rs:35:7
+  --> $DIR/borrowck-anon-fields-variant.rs:34:19
    |
 LL |       Foo::Y(ref mut a, _) => a,
    |              --------- borrow of `y.0` occurs here
 ...
-LL |       Foo::Y(ref mut b, _) => b,
-   |       ^^^^^^^^^^^^^^^^^^^^ use of borrowed `y.0`
+LL |     let b = match y {
+   |                   ^ use of borrowed `y.0`
 ...
 LL |     *a += 1;
    |     ------- borrow later used here
 
 error[E0499]: cannot borrow `y.0` as mutable more than once at a time
-  --> $DIR/borrowck-anon-fields-variant.rs:35:14
+  --> $DIR/borrowck-anon-fields-variant.rs:36:14
    |
 LL |       Foo::Y(ref mut a, _) => a,
    |              --------- first mutable borrow occurs here
diff --git a/src/test/ui/borrowck/borrowck-describe-lvalue.rs b/src/test/ui/borrowck/borrowck-describe-lvalue.rs
index 0e6c0635adb..cdcff69d6e5 100644
--- a/src/test/ui/borrowck/borrowck-describe-lvalue.rs
+++ b/src/test/ui/borrowck/borrowck-describe-lvalue.rs
@@ -164,9 +164,9 @@ fn main() {
         let mut e = E::A(3);
         let x = &mut e;
         match e {
+            //~^ ERROR cannot use `e` because it was mutably borrowed
             E::A(ref ax) =>
                 //~^ ERROR cannot borrow `e.0` as immutable because it is also borrowed as mutable
-                //~| ERROR cannot use `e` because it was mutably borrowed
                 println!("e.ax: {:?}", ax),
             E::B { x: ref bx } =>
                 //~^ ERROR cannot borrow `e.x` as immutable because it is also borrowed as mutable
diff --git a/src/test/ui/borrowck/borrowck-describe-lvalue.stderr b/src/test/ui/borrowck/borrowck-describe-lvalue.stderr
index 0f2ebbcbf3c..4b9c5a2a98f 100644
--- a/src/test/ui/borrowck/borrowck-describe-lvalue.stderr
+++ b/src/test/ui/borrowck/borrowck-describe-lvalue.stderr
@@ -238,23 +238,22 @@ LL |         drop(x);
    |              - borrow later used here
 
 error[E0503]: cannot use `e` because it was mutably borrowed
-  --> $DIR/borrowck-describe-lvalue.rs:167:13
+  --> $DIR/borrowck-describe-lvalue.rs:166:15
    |
 LL |         let x = &mut e;
    |                 ------ borrow of `e` occurs here
 LL |         match e {
-LL |             E::A(ref ax) =>
-   |             ^^^^^^^^^^^^ use of borrowed `e`
+   |               ^ use of borrowed `e`
 ...
 LL |         drop(x);
    |              - borrow later used here
 
 error[E0502]: cannot borrow `e.0` as immutable because it is also borrowed as mutable
-  --> $DIR/borrowck-describe-lvalue.rs:167:18
+  --> $DIR/borrowck-describe-lvalue.rs:168:18
    |
 LL |         let x = &mut e;
    |                 ------ mutable borrow occurs here
-LL |         match e {
+...
 LL |             E::A(ref ax) =>
    |                  ^^^^^^ immutable borrow occurs here
 ...
diff --git a/src/test/ui/borrowck/borrowck-match-already-borrowed.rs b/src/test/ui/borrowck/borrowck-match-already-borrowed.rs
index c766e6c1080..a925cbbf57b 100644
--- a/src/test/ui/borrowck/borrowck-match-already-borrowed.rs
+++ b/src/test/ui/borrowck/borrowck-match-already-borrowed.rs
@@ -6,8 +6,8 @@ enum Foo {
 fn match_enum() {
     let mut foo = Foo::B;
     let p = &mut foo;
-    let _ = match foo {
-        Foo::B => 1, //~ ERROR [E0503]
+    let _ = match foo { //~ ERROR [E0503]
+        Foo::B => 1,
         _ => 2,
         Foo::A(x) => x //~ ERROR [E0503]
     };
diff --git a/src/test/ui/borrowck/borrowck-match-already-borrowed.stderr b/src/test/ui/borrowck/borrowck-match-already-borrowed.stderr
index 286a925bb7f..39047be9de6 100644
--- a/src/test/ui/borrowck/borrowck-match-already-borrowed.stderr
+++ b/src/test/ui/borrowck/borrowck-match-already-borrowed.stderr
@@ -1,11 +1,10 @@
 error[E0503]: cannot use `foo` because it was mutably borrowed
-  --> $DIR/borrowck-match-already-borrowed.rs:10:9
+  --> $DIR/borrowck-match-already-borrowed.rs:9:19
    |
 LL |     let p = &mut foo;
    |             -------- borrow of `foo` occurs here
 LL |     let _ = match foo {
-LL |         Foo::B => 1,
-   |         ^^^^^^ use of borrowed `foo`
+   |                   ^^^ use of borrowed `foo`
 ...
 LL |     drop(p);
    |          - borrow later used here
diff --git a/src/test/ui/borrowck/issue-27282-move-match-input-into-guard.rs b/src/test/ui/borrowck/issue-27282-move-match-input-into-guard.rs
index 71f1f15654b..4109c10e2e4 100644
--- a/src/test/ui/borrowck/issue-27282-move-match-input-into-guard.rs
+++ b/src/test/ui/borrowck/issue-27282-move-match-input-into-guard.rs
@@ -10,11 +10,11 @@
 fn main() {
     let b = &mut true;
     match b {
+        //~^ ERROR use of moved value: `b` [E0382]
         &mut false => {},
         _ if { (|| { let bar = b; *bar = false; })();
                      false } => { },
         &mut true => { println!("You might think we should get here"); },
-        //~^ ERROR use of moved value: `b` [E0382]
         _ => panic!("surely we could never get here, since rustc warns it is unreachable."),
     }
 }
diff --git a/src/test/ui/borrowck/issue-27282-move-match-input-into-guard.stderr b/src/test/ui/borrowck/issue-27282-move-match-input-into-guard.stderr
index 51f9b464d76..9be1a927999 100644
--- a/src/test/ui/borrowck/issue-27282-move-match-input-into-guard.stderr
+++ b/src/test/ui/borrowck/issue-27282-move-match-input-into-guard.stderr
@@ -1,16 +1,15 @@
 error[E0382]: use of moved value: `b`
-  --> $DIR/issue-27282-move-match-input-into-guard.rs:16:14
+  --> $DIR/issue-27282-move-match-input-into-guard.rs:12:5
    |
 LL |     let b = &mut true;
    |         - move occurs because `b` has type `&mut bool`, which does not implement the `Copy` trait
+LL |     match b {
+   |     ^^^^^^^ value used here after move
 ...
 LL |         _ if { (|| { let bar = b; *bar = false; })();
    |                 --             - variable moved due to use in closure
    |                 |
    |                 value moved into closure here
-LL |                      false } => { },
-LL |         &mut true => { println!("You might think we should get here"); },
-   |              ^^^^ value used here after move
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/consts/miri_unleashed/const_refers_to_static_cross_crate.32bit.stderr b/src/test/ui/consts/miri_unleashed/const_refers_to_static_cross_crate.32bit.stderr
index 64a1214e8bf..64d8540878e 100644
--- a/src/test/ui/consts/miri_unleashed/const_refers_to_static_cross_crate.32bit.stderr
+++ b/src/test/ui/consts/miri_unleashed/const_refers_to_static_cross_crate.32bit.stderr
@@ -65,11 +65,11 @@ LL |         U8_MUT2 => true,
    |         ^^^^^^^
 
 warning: any use of this value will cause an error
-  --> $DIR/const_refers_to_static_cross_crate.rs:32:51
+  --> $DIR/const_refers_to_static_cross_crate.rs:32:20
    |
 LL | / const U8_MUT3: &u8 = {
 LL | |     unsafe { match static_cross_crate::OPT_ZERO { Some(ref u) => u, None => panic!() } }
-   | |                                                   ^^^^^^^^^^^ constant accesses static
+   | |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constant accesses static
 LL | |
 LL | |
 LL | |
diff --git a/src/test/ui/consts/miri_unleashed/const_refers_to_static_cross_crate.64bit.stderr b/src/test/ui/consts/miri_unleashed/const_refers_to_static_cross_crate.64bit.stderr
index 66fe4ec0760..8e793ab3f0d 100644
--- a/src/test/ui/consts/miri_unleashed/const_refers_to_static_cross_crate.64bit.stderr
+++ b/src/test/ui/consts/miri_unleashed/const_refers_to_static_cross_crate.64bit.stderr
@@ -65,11 +65,11 @@ LL |         U8_MUT2 => true,
    |         ^^^^^^^
 
 warning: any use of this value will cause an error
-  --> $DIR/const_refers_to_static_cross_crate.rs:32:51
+  --> $DIR/const_refers_to_static_cross_crate.rs:32:20
    |
 LL | / const U8_MUT3: &u8 = {
 LL | |     unsafe { match static_cross_crate::OPT_ZERO { Some(ref u) => u, None => panic!() } }
-   | |                                                   ^^^^^^^^^^^ constant accesses static
+   | |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constant accesses static
 LL | |
 LL | |
 LL | |
diff --git a/src/test/ui/issues/issue-17385.rs b/src/test/ui/issues/issue-17385.rs
index 93364d2f625..7400aadb059 100644
--- a/src/test/ui/issues/issue-17385.rs
+++ b/src/test/ui/issues/issue-17385.rs
@@ -15,8 +15,8 @@ impl Drop for Enum {
 fn main() {
     let foo = X(1);
     drop(foo);
-    match foo {
-        X(1) => (), //~ ERROR use of moved value
+    match foo { //~ ERROR use of moved value
+        X(1) => (),
         _ => unreachable!()
     }
 
diff --git a/src/test/ui/issues/issue-17385.stderr b/src/test/ui/issues/issue-17385.stderr
index 28c22260c38..77aa201b335 100644
--- a/src/test/ui/issues/issue-17385.stderr
+++ b/src/test/ui/issues/issue-17385.stderr
@@ -1,13 +1,12 @@
 error[E0382]: use of moved value: `foo`
-  --> $DIR/issue-17385.rs:19:11
+  --> $DIR/issue-17385.rs:18:5
    |
 LL |     let foo = X(1);
    |         --- move occurs because `foo` has type `X`, which does not implement the `Copy` trait
 LL |     drop(foo);
    |          --- value moved here
 LL |     match foo {
-LL |         X(1) => (),
-   |           ^ value used here after move
+   |     ^^^^^^^^^ value used here after move
 
 error[E0382]: use of moved value: `e`
   --> $DIR/issue-17385.rs:25:11
diff --git a/src/test/ui/nll/borrowed-match-issue-45045.rs b/src/test/ui/nll/borrowed-match-issue-45045.rs
index 0cd8e956d30..978eeb868ed 100644
--- a/src/test/ui/nll/borrowed-match-issue-45045.rs
+++ b/src/test/ui/nll/borrowed-match-issue-45045.rs
@@ -10,8 +10,8 @@ fn main() {
     let f = &mut e;
     let g = f;
     match e {
-        Xyz::A => println!("a"),
         //~^ cannot use `e` because it was mutably borrowed [E0503]
+        Xyz::A => println!("a"),
         Xyz::B => println!("b"),
     };
     *g = Xyz::B;
diff --git a/src/test/ui/nll/borrowed-match-issue-45045.stderr b/src/test/ui/nll/borrowed-match-issue-45045.stderr
index 1607304e671..9d4682667dd 100644
--- a/src/test/ui/nll/borrowed-match-issue-45045.stderr
+++ b/src/test/ui/nll/borrowed-match-issue-45045.stderr
@@ -1,11 +1,11 @@
 error[E0503]: cannot use `e` because it was mutably borrowed
-  --> $DIR/borrowed-match-issue-45045.rs:13:9
+  --> $DIR/borrowed-match-issue-45045.rs:12:11
    |
 LL |     let f = &mut e;
    |             ------ borrow of `e` occurs here
-...
-LL |         Xyz::A => println!("a"),
-   |         ^^^^^^ use of borrowed `e`
+LL |     let g = f;
+LL |     match e {
+   |           ^ use of borrowed `e`
 ...
 LL |     *g = Xyz::B;
    |     ----------- borrow later used here
diff --git a/src/test/ui/nll/match-cfg-fake-edges2.rs b/src/test/ui/nll/match-cfg-fake-edges2.rs
index 84c0dec2fe5..e61db71220e 100644
--- a/src/test/ui/nll/match-cfg-fake-edges2.rs
+++ b/src/test/ui/nll/match-cfg-fake-edges2.rs
@@ -7,8 +7,8 @@ fn all_previous_tests_may_be_done(y: &mut (bool, bool)) {
     let r = &mut y.1;
     // We don't actually test y.1 to select the second arm, but we don't want
     // borrowck results to be based on the order we match patterns.
-    match y {
-        (false, true) => 1, //~ ERROR cannot use `y.1` because it was mutably borrowed
+    match y { //~ ERROR cannot use `y.1` because it was mutably borrowed
+        (false, true) => 1,
         (true, _) => {
             r;
             2
diff --git a/src/test/ui/nll/match-cfg-fake-edges2.stderr b/src/test/ui/nll/match-cfg-fake-edges2.stderr
index eab89658e79..0ce83849b9f 100644
--- a/src/test/ui/nll/match-cfg-fake-edges2.stderr
+++ b/src/test/ui/nll/match-cfg-fake-edges2.stderr
@@ -1,12 +1,12 @@
 error[E0503]: cannot use `y.1` because it was mutably borrowed
-  --> $DIR/match-cfg-fake-edges2.rs:11:17
+  --> $DIR/match-cfg-fake-edges2.rs:10:5
    |
 LL |     let r = &mut y.1;
    |             -------- borrow of `y.1` occurs here
 ...
-LL |         (false, true) => 1,
-   |                 ^^^^ use of borrowed `y.1`
-LL |         (true, _) => {
+LL |     match y {
+   |     ^^^^^^^ use of borrowed `y.1`
+...
 LL |             r;
    |             - borrow later used here
 
diff --git a/src/test/ui/nll/match-on-borrowed.rs b/src/test/ui/nll/match-on-borrowed.rs
index aba0a7f71f5..447dabeb47e 100644
--- a/src/test/ui/nll/match-on-borrowed.rs
+++ b/src/test/ui/nll/match-on-borrowed.rs
@@ -45,8 +45,9 @@ fn enum_example(mut e: E) {
         E::W => panic!(),
     };
     match e { // Don't know that E uses a tag for its discriminant
+        //~^ ERROR
         _ if false => (),
-        E::V(_, r) => (), //~ ERROR
+        E::V(_, r) => (),
         E::W => (),
     }
     x;
@@ -58,8 +59,9 @@ fn indirect_enum_example(mut f: &mut E) {
         E::W => panic!(),
     };
     match f { // Don't know that E uses a tag for its discriminant
+        //~^ ERROR
         _ if false => (),
-        E::V(_, r) => (), //~ ERROR
+        E::V(_, r) => (),
         E::W => (),
     }
     x;
@@ -77,7 +79,8 @@ fn match_on_muatbly_borrowed_ref(mut p: &bool) {
 fn match_on_borrowed(mut t: bool) {
     let x = &mut t;
     match t {
-        true => (), //~ ERROR
+        //~^ ERROR
+        true => (),
         false => (),
     }
     x;
diff --git a/src/test/ui/nll/match-on-borrowed.stderr b/src/test/ui/nll/match-on-borrowed.stderr
index f9c9a846322..2121b59b02d 100644
--- a/src/test/ui/nll/match-on-borrowed.stderr
+++ b/src/test/ui/nll/match-on-borrowed.stderr
@@ -1,41 +1,40 @@
 error[E0503]: cannot use `e` because it was mutably borrowed
-  --> $DIR/match-on-borrowed.rs:49:9
+  --> $DIR/match-on-borrowed.rs:47:11
    |
 LL |         E::V(ref mut x, _) => x,
    |              --------- borrow of `e.0` occurs here
 ...
-LL |         E::V(_, r) => (),
-   |         ^^^^^^^^^^ use of borrowed `e.0`
+LL |     match e { // Don't know that E uses a tag for its discriminant
+   |           ^ use of borrowed `e.0`
 ...
 LL |     x;
    |     - borrow later used here
 
 error[E0503]: cannot use `*f` because it was mutably borrowed
-  --> $DIR/match-on-borrowed.rs:62:9
+  --> $DIR/match-on-borrowed.rs:61:11
    |
 LL |         E::V(ref mut x, _) => x,
    |              --------- borrow of `f.0` occurs here
 ...
-LL |         E::V(_, r) => (),
-   |         ^^^^^^^^^^ use of borrowed `f.0`
+LL |     match f { // Don't know that E uses a tag for its discriminant
+   |           ^ use of borrowed `f.0`
 ...
 LL |     x;
    |     - borrow later used here
 
 error[E0503]: cannot use `t` because it was mutably borrowed
-  --> $DIR/match-on-borrowed.rs:80:9
+  --> $DIR/match-on-borrowed.rs:81:5
    |
 LL |     let x = &mut t;
    |             ------ borrow of `t` occurs here
 LL |     match t {
-LL |         true => (),
-   |         ^^^^ use of borrowed `t`
+   |     ^^^^^^^ use of borrowed `t`
 ...
 LL |     x;
    |     - borrow later used here
 
 error[E0381]: use of possibly-uninitialized variable: `n`
-  --> $DIR/match-on-borrowed.rs:90:11
+  --> $DIR/match-on-borrowed.rs:93:11
    |
 LL |     match n {}
    |           ^ use of possibly-uninitialized `n`
diff --git a/src/test/ui/rfc-2008-non-exhaustive/borrowck-non-exhaustive.rs b/src/test/ui/rfc-2008-non-exhaustive/borrowck-non-exhaustive.rs
index 00dcf89c7aa..2ad92b79444 100644
--- a/src/test/ui/rfc-2008-non-exhaustive/borrowck-non-exhaustive.rs
+++ b/src/test/ui/rfc-2008-non-exhaustive/borrowck-non-exhaustive.rs
@@ -10,8 +10,8 @@ fn main() {
     let mut x = NonExhaustiveMonovariant::Variant(1);
     let y = &mut x;
     match x {
-        NonExhaustiveMonovariant::Variant(_) => {},
         //~^ ERROR cannot use `x` because it was mutably borrowed
+        NonExhaustiveMonovariant::Variant(_) => {},
         _ => {},
     }
     drop(y);
diff --git a/src/test/ui/rfc-2008-non-exhaustive/borrowck-non-exhaustive.stderr b/src/test/ui/rfc-2008-non-exhaustive/borrowck-non-exhaustive.stderr
index 9edfa84cbc0..de730ce1030 100644
--- a/src/test/ui/rfc-2008-non-exhaustive/borrowck-non-exhaustive.stderr
+++ b/src/test/ui/rfc-2008-non-exhaustive/borrowck-non-exhaustive.stderr
@@ -1,11 +1,10 @@
 error[E0503]: cannot use `x` because it was mutably borrowed
-  --> $DIR/borrowck-non-exhaustive.rs:13:9
+  --> $DIR/borrowck-non-exhaustive.rs:12:11
    |
 LL |     let y = &mut x;
    |             ------ borrow of `x` occurs here
 LL |     match x {
-LL |         NonExhaustiveMonovariant::Variant(_) => {},
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ use of borrowed `x`
+   |           ^ use of borrowed `x`
 ...
 LL |     drop(y);
    |          - borrow later used here
diff --git a/src/test/ui/union/union-unsafe.mir.stderr b/src/test/ui/union/union-unsafe.mir.stderr
index 84a7eb2ef2e..318b00ddea9 100644
--- a/src/test/ui/union/union-unsafe.mir.stderr
+++ b/src/test/ui/union/union-unsafe.mir.stderr
@@ -55,10 +55,10 @@ LL |     let U1 { a } = u1;
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:65:20
+  --> $DIR/union-unsafe.rs:65:12
    |
 LL |     if let U1 { a: 12 } = u1 {}
-   |                    ^^ access to union field
+   |            ^^^^^^^^^^^^ access to union field
    |
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior