Tweak wording and spans of closure lifetime errors

src/librustc/infer/error_reporting/nice_region_error/outlives_closure.rs

@@ -69,16 +69,46 @@ impl<'a, 'gcx, 'tcx> NiceRegionError<'a, 'gcx, 'tcx> {
  sup_sp,
  "borrowed data cannot be stored outside of its closure");
  err.span_label(sup_sp, "cannot be stored outside of its closure");
- if sup_sp == origin_sp {
+ if origin_sp == sup_sp || origin_sp.contains(sup_sp) {
+// // sup_sp == origin.span():
+//
+// let mut x = None;
+// ----- borrowed data cannot be stored into here...
+// with_int(|y| x = Some(y));
+// --- ^ cannot be stored outside of its closure
+// |
+// ...because it cannot outlive this closure
+//
+// // origin.contains(&sup_sp):
+//
+// let mut f: Option<&u32> = None;
+// ----- borrowed data cannot be stored into here...
+// closure_expecting_bound(|x: &'x u32| {
+// ------------ ... because it cannot outlive this closure
+// f = Some(x);
+// ^ cannot be stored outside of its closure
  err.span_label(*external_span,
  "borrowed data cannot be stored into here...");
  err.span_label(*closure_span,
  "...because it cannot outlive this closure");
  } else {
+// FIXME: the wording for this case could be much improved
+//
+// let mut lines_to_use: Vec<&CrateId> = Vec::new();
+// - cannot infer an appropriate lifetime...
+// let push_id = |installed_id: &CrateId| {
+// ------- ------------------------ borrowed data cannot outlive this closure
+// |
+// ...so that variable is valid at time of its declaration
+// lines_to_use.push(installed_id);
+// ^^^^^^^^^^^^ cannot be stored outside of its closure
+ err.span_label(origin_sp,
+ "cannot infer an appropriate lifetime...");
+ err.span_label(*external_span,
+ "...so that variable is valid at time of its \
+ declaration");
  err.span_label(*closure_span,
  "borrowed data cannot outlive this closure");
- err.span_label(origin_sp,
- "cannot infer an appropriate lifetime");
  }
  err.emit();
  return Some(ErrorReported);

src/test/ui/borrowck/issue-7573.rs

@@ -28,6 +28,7 @@ pub fn remove_package_from_database() {
  //~^ NOTE cannot infer an appropriate lifetime
  let push_id = |installed_id: &CrateId| {
  //~^ NOTE borrowed data cannot outlive this closure
+ //~| NOTE ...so that variable is valid at time of its declaration
  lines_to_use.push(installed_id);
  //~^ ERROR borrowed data cannot be stored outside of its closure
  //~| NOTE cannot be stored outside of its closure

src/test/ui/borrowck/issue-7573.stderr

@@ -1,13 +1,15 @@
 error: borrowed data cannot be stored outside of its closure
- --> $DIR/issue-7573.rs:31:27
+ --> $DIR/issue-7573.rs:32:27
  |
 27 | let mut lines_to_use: Vec<&CrateId> = Vec::new();
- | - cannot infer an appropriate lifetime
+ | - cannot infer an appropriate lifetime...
 28 | //~^ NOTE cannot infer an appropriate lifetime
 29 | let push_id = |installed_id: &CrateId| {
- | ------------------------ borrowed data cannot outlive this closure
-30 | //~^ NOTE borrowed data cannot outlive this closure
-31 | lines_to_use.push(installed_id);
+ | ------- ------------------------ borrowed data cannot outlive this closure
+ | |
+ | ...so that variable is valid at time of its declaration
+...
+32 | lines_to_use.push(installed_id);
  | ^^^^^^^^^^^^ cannot be stored outside of its closure
 
 error: aborting due to previous error

src/test/ui/borrowck/regions-escape-bound-fn.stderr

@@ -1,12 +1,12 @@
 error: borrowed data cannot be stored outside of its closure
  --> $DIR/regions-escape-bound-fn.rs:18:27
  |
+17 | let mut x: Option<&isize> = None;
+ | ----- borrowed data cannot be stored into here...
 18 | with_int(|y| x = Some(y));
- | --- -----^-
- | | | |
- | | | cannot be stored outside of its closure
- | | cannot infer an appropriate lifetime
- | borrowed data cannot outlive this closure
+ | --- ^ cannot be stored outside of its closure
+ | |
+ | ...because it cannot outlive this closure
 
 error: aborting due to previous error
 

src/test/ui/borrowck/regions-escape-unboxed-closure.stderr

@@ -1,12 +1,12 @@
 error: borrowed data cannot be stored outside of its closure
  --> $DIR/regions-escape-unboxed-closure.rs:16:32
  |
+15 | let mut x: Option<&isize> = None;
+ | ----- borrowed data cannot be stored into here...
 16 | with_int(&mut |y| x = Some(y));
- | --- -----^-
- | | | |
- | | | cannot be stored outside of its closure
- | | cannot infer an appropriate lifetime
- | borrowed data cannot outlive this closure
+ | --- ^ cannot be stored outside of its closure
+ | |
+ | ...because it cannot outlive this closure
 
 error: aborting due to previous error
 

src/test/ui/closure-expected-type/expect-region-supply-region.stderr

@@ -1,24 +1,22 @@
 error: borrowed data cannot be stored outside of its closure
  --> $DIR/expect-region-supply-region.rs:28:18
  |
+26 | let mut f: Option<&u32> = None;
+ | ----- borrowed data cannot be stored into here...
 27 | closure_expecting_bound(|x| {
- | --- borrowed data cannot outlive this closure
+ | --- ...because it cannot outlive this closure
 28 | f = Some(x); //~ ERROR borrowed data cannot be stored outside of its closure
- | -----^-
- | | |
- | | cannot be stored outside of its closure
- | cannot infer an appropriate lifetime
+ | ^ cannot be stored outside of its closure
 
 error: borrowed data cannot be stored outside of its closure
  --> $DIR/expect-region-supply-region.rs:38:18
  |
+36 | let mut f: Option<&u32> = None;
+ | ----- borrowed data cannot be stored into here...
 37 | closure_expecting_bound(|x: &u32| {
- | --------- borrowed data cannot outlive this closure
+ | --------- ...because it cannot outlive this closure
 38 | f = Some(x); //~ ERROR borrowed data cannot be stored outside of its closure
- | -----^-
- | | |
- | | cannot be stored outside of its closure
- | cannot infer an appropriate lifetime
+ | ^ cannot be stored outside of its closure
 
 error[E0308]: mismatched types
  --> $DIR/expect-region-supply-region.rs:47:33
@@ -87,14 +85,14 @@ note: ...does not necessarily outlive the anonymous lifetime #2 defined on the b
 error: borrowed data cannot be stored outside of its closure
  --> $DIR/expect-region-supply-region.rs:52:18
  |
+43 | let mut f: Option<&u32> = None;
+ | ----- borrowed data cannot be stored into here...
+...
 47 | closure_expecting_bound(|x: &'x u32| {
- | ------------ borrowed data cannot outlive this closure
+ | ------------ ...because it cannot outlive this closure
 ...
 52 | f = Some(x);
- | -----^-
- | | |
- | | cannot be stored outside of its closure
- | cannot infer an appropriate lifetime
+ | ^ cannot be stored outside of its closure
 
 error: aborting due to 5 previous errors