more concise debug output when dumping the value of a region

8 files changed, 77 insertions, 28 deletions

diff --git a/src/librustc_mir/borrow_check/nll/region_infer/values.rs b/src/librustc_mir/borrow_check/nll/region_infer/values.rs
index 849ccd3259a..5f23a0e5790 100644
--- a/src/librustc_mir/borrow_check/nll/region_infer/values.rs
+++ b/src/librustc_mir/borrow_check/nll/region_infer/values.rs
@@ -215,8 +215,11 @@ impl RegionValues {
         // FIXME. We could optimize this by improving
         // `BitMatrix::merge` so it does not always merge an entire
         // row.
-        debug!("add_universal_regions_outlived_by(from_region={:?}, to_region={:?})",
-               from_region, to_region);
+        debug!(
+            "add_universal_regions_outlived_by(from_region={:?}, to_region={:?})",
+            from_region,
+            to_region
+        );
         let mut changed = false;
         for elem in self.elements.all_universal_region_indices() {
             if self.contains(from_region, elem) {
@@ -269,24 +272,70 @@ impl RegionValues {
         let mut result = String::new();
         result.push_str("{");
 
-        for (index, element) in self.elements_contained_in(r).enumerate() {
-            if index > 0 {
-                result.push_str(", ");
-            }
+        // Set to Some(l1, l2) when we have observed all the locations
+        // from l1..=l2 (inclusive) but not yet printed them. This
+        // gets extended if we then see l3 where l3 is the successor
+        // to l2.
+        let mut open_location: Option<(Location, Location)> = None;
+
+        let mut sep = "";
+        let mut push_sep = |s: &mut String| {
+            s.push_str(sep);
+            sep = ", ";
+        };
 
+        for element in self.elements_contained_in(r) {
             match element {
                 RegionElement::Location(l) => {
-                    result.push_str(&format!("{:?}", l));
+                    if let Some((location1, location2)) = open_location {
+                        if location2.block == l.block
+                            && location2.statement_index == l.statement_index - 1
+                        {
+                            open_location = Some((location1, l));
+                            continue;
+                        }
+
+                        push_sep(&mut result);
+                        Self::push_location_range(&mut result, location1, location2);
+                    }
+
+                    open_location = Some((l, l));
                 }
 
                 RegionElement::UniversalRegion(fr) => {
+                    if let Some((location1, location2)) = open_location {
+                        push_sep(&mut result);
+                        Self::push_location_range(&mut result, location1, location2);
+                        open_location = None;
+                    }
+
+                    push_sep(&mut result);
                     result.push_str(&format!("{:?}", fr));
                 }
             }
         }
 
+        if let Some((location1, location2)) = open_location {
+            push_sep(&mut result);
+            Self::push_location_range(&mut result, location1, location2);
+        }
+
         result.push_str("}");
 
         result
     }
+
+    fn push_location_range(str: &mut String, location1: Location, location2: Location) {
+        if location1 == location2 {
+            str.push_str(&format!("{:?}", location1));
+        } else {
+            assert_eq!(location1.block, location2.block);
+            str.push_str(&format!(
+                "{:?}[{}..={}]",
+                location1.block,
+                location1.statement_index,
+                location2.statement_index
+            ));
+        }
+    }
 }
diff --git a/src/test/mir-opt/nll/named-lifetimes-basic.rs b/src/test/mir-opt/nll/named-lifetimes-basic.rs
index f14979f9733..8feac15d69a 100644
--- a/src/test/mir-opt/nll/named-lifetimes-basic.rs
+++ b/src/test/mir-opt/nll/named-lifetimes-basic.rs
@@ -34,15 +34,15 @@ fn main() {
 // | '_#4r    | Local    | ['_#4r]
 // |
 // | Inferred Region Values
-// | '_#0r    | {'_#0r, bb0[0], bb0[1]}
-// | '_#1r    | {'_#1r, bb0[0], bb0[1]}
-// | '_#2r    | {'_#2r, bb0[0], bb0[1]}
-// | '_#3r    | {'_#3r, bb0[0], bb0[1]}
-// | '_#4r    | {'_#4r, bb0[0], bb0[1]}
-// | '_#5r    | {'_#1r, bb0[0], bb0[1]}
-// | '_#6r    | {'_#2r, bb0[0], bb0[1]}
-// | '_#7r    | {'_#1r, bb0[0], bb0[1]}
-// | '_#8r    | {'_#3r, bb0[0], bb0[1]}
+// | '_#0r    | {'_#0r, bb0[0..=1]}
+// | '_#1r    | {'_#1r, bb0[0..=1]}
+// | '_#2r    | {'_#2r, bb0[0..=1]}
+// | '_#3r    | {'_#3r, bb0[0..=1]}
+// | '_#4r    | {'_#4r, bb0[0..=1]}
+// | '_#5r    | {'_#1r, bb0[0..=1]}
+// | '_#6r    | {'_#2r, bb0[0..=1]}
+// | '_#7r    | {'_#1r, bb0[0..=1]}
+// | '_#8r    | {'_#3r, bb0[0..=1]}
 // |
 // ...
 // fn use_x(_1: &'_#5r mut i32, _2: &'_#6r u32, _3: &'_#7r u32, _4: &'_#8r u32) -> bool {
diff --git a/src/test/mir-opt/nll/reborrow-basic.rs b/src/test/mir-opt/nll/reborrow-basic.rs
index 9e6d6aaee15..f69c51c3562 100644
--- a/src/test/mir-opt/nll/reborrow-basic.rs
+++ b/src/test/mir-opt/nll/reborrow-basic.rs
@@ -28,9 +28,9 @@ fn main() {
 
 // END RUST SOURCE
 // START rustc.main.nll.0.mir
-// | '_#7r    | {bb0[6], bb0[7], bb0[8], bb0[9], bb0[10], bb0[11], bb0[12], bb0[13], bb0[14]}
+// | '_#7r    | {bb0[6..=14]}
 // ...
-// | '_#9r    | {bb0[11], bb0[12], bb0[13], bb0[14]}
+// | '_#9r    | {bb0[11..=14]}
 // ...
 // let _2: &'_#7r mut i32;
 // ...
diff --git a/src/test/mir-opt/nll/region-liveness-basic.rs b/src/test/mir-opt/nll/region-liveness-basic.rs
index ab99d79d7f3..e9834305550 100644
--- a/src/test/mir-opt/nll/region-liveness-basic.rs
+++ b/src/test/mir-opt/nll/region-liveness-basic.rs
@@ -31,8 +31,8 @@ fn main() {
 
 // END RUST SOURCE
 // START rustc.main.nll.0.mir
-// | '_#2r    | {bb2[0], bb2[1], bb3[0], bb3[1]}
-// | '_#3r    | {bb2[1], bb3[0], bb3[1]}
+// | '_#2r    | {bb2[0..=1], bb3[0..=1]}
+// | '_#3r    | {bb2[1], bb3[0..=1]}
 // ...
 //             let _2: &'_#3r usize;
 // END rustc.main.nll.0.mir
diff --git a/src/test/mir-opt/nll/region-liveness-drop-may-dangle.rs b/src/test/mir-opt/nll/region-liveness-drop-may-dangle.rs
index 515772a9427..c14ce6bb581 100644
--- a/src/test/mir-opt/nll/region-liveness-drop-may-dangle.rs
+++ b/src/test/mir-opt/nll/region-liveness-drop-may-dangle.rs
@@ -44,7 +44,7 @@ unsafe impl<#[may_dangle] T> Drop for Wrap<T> {
 
 // END RUST SOURCE
 // START rustc.main.nll.0.mir
-// | '_#6r    | {bb2[3], bb2[4], bb2[5], bb3[0], bb3[1]}
+// | '_#6r    | {bb2[3..=5], bb3[0..=1]}
 // ...
 // let _2: Wrap<&'_#6r usize>;
 // END rustc.main.nll.0.mir
diff --git a/src/test/mir-opt/nll/region-liveness-drop-no-may-dangle.rs b/src/test/mir-opt/nll/region-liveness-drop-no-may-dangle.rs
index a257910b0b8..058a57fe612 100644
--- a/src/test/mir-opt/nll/region-liveness-drop-no-may-dangle.rs
+++ b/src/test/mir-opt/nll/region-liveness-drop-no-may-dangle.rs
@@ -46,7 +46,7 @@ impl<T> Drop for Wrap<T> {
 
 // END RUST SOURCE
 // START rustc.main.nll.0.mir
-// | '_#6r    | {bb2[3], bb2[4], bb2[5], bb3[0], bb3[1], bb3[2], bb4[0], bb5[0], bb5[1], bb5[2], bb6[0], bb7[0], bb7[1], bb8[0]}
+// | '_#6r    | {bb2[3..=5], bb3[0..=2], bb4[0], bb5[0..=2], bb6[0], bb7[0..=1], bb8[0]}
 // ...
 // let _2: Wrap<&'_#6r usize>;
 // END rustc.main.nll.0.mir
diff --git a/src/test/mir-opt/nll/region-liveness-two-disjoint-uses.rs b/src/test/mir-opt/nll/region-liveness-two-disjoint-uses.rs
index 3041c2cb061..821cd736671 100644
--- a/src/test/mir-opt/nll/region-liveness-two-disjoint-uses.rs
+++ b/src/test/mir-opt/nll/region-liveness-two-disjoint-uses.rs
@@ -36,10 +36,10 @@ fn main() {
 
 // END RUST SOURCE
 // START rustc.main.nll.0.mir
-// | '_#2r    | {bb2[0], bb2[1], bb3[0], bb3[1]}
+// | '_#2r    | {bb2[0..=1], bb3[0..=1]}
 // ...
-// | '_#4r    | {bb8[1], bb8[2], bb8[3], bb8[4]}
-// | '_#5r    | {bb2[1], bb3[0], bb3[1], bb8[2], bb8[3], bb8[4]}
+// | '_#4r    | {bb8[1..=4]}
+// | '_#5r    | {bb2[1], bb3[0..=1], bb8[2..=4]}
 // ...
 // let mut _2: &'_#5r usize;
 // ...
diff --git a/src/test/mir-opt/nll/region-subtyping-basic.rs b/src/test/mir-opt/nll/region-subtyping-basic.rs
index 5a3f831331c..a3f68ed5ebf 100644
--- a/src/test/mir-opt/nll/region-subtyping-basic.rs
+++ b/src/test/mir-opt/nll/region-subtyping-basic.rs
@@ -32,9 +32,9 @@ fn main() {
 
 // END RUST SOURCE
 // START rustc.main.nll.0.mir
-// | '_#2r    | {bb2[0], bb2[1], bb2[2], bb2[3], bb2[4], bb2[5], bb2[6], bb3[0], bb3[1]}
-// | '_#3r    | {bb2[1], bb2[2], bb2[3], bb2[4], bb2[5], bb2[6], bb3[0], bb3[1]}
-// | '_#4r    | {bb2[5], bb2[6], bb3[0], bb3[1]}
+// | '_#2r    | {bb2[0..=6], bb3[0..=1]}
+// | '_#3r    | {bb2[1..=6], bb3[0..=1]}
+// | '_#4r    | {bb2[5..=6], bb3[0..=1]}
 // END rustc.main.nll.0.mir
 // START rustc.main.nll.0.mir
 // let _2: &'_#3r usize;