Revert "modify leak-check to track only outgoing edges from placeholders"

This reverts commit 2e01db4b396a1e161f7a73933fff34bc9421dba0.

Author: nikomatsakis

src/librustc_infer/infer/region_constraints/leak_check.rs

@@ -42,23 +42,10 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
                 _ => bug!("leak_check: expected placeholder found {:?}", placeholder_region,),
             };
 
-            // Find all regions that this placeholder `!p` must outlive -- i.e.,
-            // any region `r` where `!p: r` must hold. It is an error if any
-            // such region `r` is another placeholder or in a universe that
-            // can't see the placeholder. (This is actually incorrect, because
-            // we don't take into account the possibility of bounds in
-            // environment that tell us that the placeholder may be related to
-            // other regions).
-            //
-            // Note that we *don't* look for cases like `r: !p`. This is
-            // because:
-            //
-            // * If `r` is some other placeholder `!p1`, then we'll find the
-            //   error when we search the regions that `!p1` must outlive.
-            // * If `r` is a variable in some outer universe, then it can
-            //   potentially be assigned to `'static`, so this relation could
-            //   hold.
-            let mut taint_set = TaintSet::new(TaintDirections::outgoing(), placeholder_region);
+            // Find all regions that are related to this placeholder
+            // in some way. This means any region that either outlives
+            // or is outlived by a placeholder.
+            let mut taint_set = TaintSet::new(TaintDirections::both(), placeholder_region);
             taint_set.fixed_point(
                 tcx,
                 self.undo_log.region_constraints(),

src/test/ui/closure-expected-type/expect-fn-supply-fn.rs

@@ -28,14 +28,14 @@ fn expect_free_supply_bound() {
     // Here, we are given a function whose region is bound at closure level,
     // but we expect one bound in the argument. Error results.
     with_closure_expecting_fn_with_free_region(|x: fn(&u32), y| {});
-    //~^ ERROR mismatched types
+    //~^ ERROR type mismatch
 }
 
 fn expect_bound_supply_free_from_fn<'x>(x: &'x u32) {
     // Here, we are given a `fn(&u32)` but we expect a `fn(&'x
     // u32)`. In principle, this could be ok, but we demand equality.
     with_closure_expecting_fn_with_bound_region(|x: fn(&'x u32), y| {});
-    //~^ ERROR mismatched types
+    //~^ ERROR type mismatch
 }
 
 fn expect_bound_supply_free_from_closure() {
@@ -44,7 +44,7 @@ fn expect_bound_supply_free_from_closure() {
     // the argument level.
     type Foo<'a> = fn(&'a u32);
     with_closure_expecting_fn_with_bound_region(|x: Foo<'_>, y| {
-    //~^ ERROR mismatched types
+    //~^ ERROR type mismatch
     });
 }
 

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

@@ -36,33 +36,46 @@ note: ...does not necessarily outlive the anonymous lifetime #2 defined on the b
 LL |     with_closure_expecting_fn_with_free_region(|x: fn(&'x u32), y| {});
    |                                                ^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0308]: mismatched types
-  --> $DIR/expect-fn-supply-fn.rs:30:52
+error[E0631]: type mismatch in closure arguments
+  --> $DIR/expect-fn-supply-fn.rs:30:5
    |
+LL | fn with_closure_expecting_fn_with_free_region<F>(_: F)
+   |    ------------------------------------------ required by a bound in this
+LL |     where F: for<'a> FnOnce(fn(&'a u32), &i32)
+   |                      ------------------------- required by this bound in `with_closure_expecting_fn_with_free_region`
+...
 LL |     with_closure_expecting_fn_with_free_region(|x: fn(&u32), y| {});
-   |                                                    ^^^^^^^^ one type is more general than the other
-   |
-   = note: expected fn pointer `fn(&u32)`
-              found fn pointer `for<'r> fn(&'r u32)`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ---------------- found signature of `fn(for<'r> fn(&'r u32), _) -> _`
+   |     |
+   |     expected signature of `fn(fn(&'a u32), &i32) -> _`
 
-error[E0308]: mismatched types
-  --> $DIR/expect-fn-supply-fn.rs:37:53
+error[E0631]: type mismatch in closure arguments
+  --> $DIR/expect-fn-supply-fn.rs:37:5
    |
+LL | fn with_closure_expecting_fn_with_bound_region<F>(_: F)
+   |    ------------------------------------------- required by a bound in this
+LL |     where F: FnOnce(fn(&u32), &i32)
+   |              ---------------------- required by this bound in `with_closure_expecting_fn_with_bound_region`
+...
 LL |     with_closure_expecting_fn_with_bound_region(|x: fn(&'x u32), y| {});
-   |                                                     ^^^^^^^^^^^ one type is more general than the other
-   |
-   = note: expected fn pointer `for<'r> fn(&'r u32)`
-              found fn pointer `fn(&'x u32)`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ------------------- found signature of `fn(fn(&'x u32), _) -> _`
+   |     |
+   |     expected signature of `fn(for<'r> fn(&'r u32), &i32) -> _`
 
-error[E0308]: mismatched types
-  --> $DIR/expect-fn-supply-fn.rs:46:53
+error[E0631]: type mismatch in closure arguments
+  --> $DIR/expect-fn-supply-fn.rs:46:5
    |
+LL | fn with_closure_expecting_fn_with_bound_region<F>(_: F)
+   |    ------------------------------------------- required by a bound in this
+LL |     where F: FnOnce(fn(&u32), &i32)
+   |              ---------------------- required by this bound in `with_closure_expecting_fn_with_bound_region`
+...
 LL |     with_closure_expecting_fn_with_bound_region(|x: Foo<'_>, y| {
-   |                                                     ^^^^^^^ one type is more general than the other
-   |
-   = note: expected fn pointer `for<'r> fn(&'r u32)`
-              found fn pointer `fn(&u32)`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ --------------- found signature of `for<'r> fn(fn(&'r u32), _) -> _`
+   |     |
+   |     expected signature of `fn(for<'r> fn(&'r u32), &i32) -> _`
 
 error: aborting due to 5 previous errors
 
-For more information about this error, try `rustc --explain E0308`.
+Some errors have detailed explanations: E0308, E0631.
+For more information about an error, try `rustc --explain E0308`.

src/test/ui/hr-subtype/hr-subtype.bound_a_b_vs_bound_a.stderr

@@ -1,14 +1,17 @@
-error: fatal error triggered by #[rustc_error]
-  --> $DIR/hr-subtype.rs:96:1
+error[E0308]: mismatched types
+  --> $DIR/hr-subtype.rs:39:26
    |
-LL | / fn main() {
-LL | |
-LL | |
-LL | |
-...  |
-LL | |
-LL | | }
-   | |_^
+LL |               gimme::<$t1>(None::<$t2>);
+   |                            ^^^^^^^^^^^ expected concrete lifetime, found bound lifetime parameter 'a
+...
+LL | / check! { bound_a_b_vs_bound_a: (for<'a,'b> fn(&'a u32, &'b u32),
+LL | |                                 for<'a>    fn(&'a u32, &'a u32)) }
+   | |__________________________________________________________________- in this macro invocation
+   |
+   = note: expected enum `std::option::Option<for<'a, 'b> fn(&'a u32, &'b u32)>`
+              found enum `std::option::Option<for<'a> fn(&'a u32, &'a u32)>`
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0308`.

src/test/ui/hr-subtype/hr-subtype.bound_a_vs_bound_a.stderr

@@ -1,11 +1,11 @@
 error: fatal error triggered by #[rustc_error]
-  --> $DIR/hr-subtype.rs:96:1
+  --> $DIR/hr-subtype.rs:100:1
    |
 LL | / fn main() {
 LL | |
 LL | |
 LL | |
-...  |
+LL | |
 LL | |
 LL | | }
    | |_^

src/test/ui/hr-subtype/hr-subtype.bound_a_vs_bound_b.stderr

@@ -1,11 +1,11 @@
 error: fatal error triggered by #[rustc_error]
-  --> $DIR/hr-subtype.rs:96:1
+  --> $DIR/hr-subtype.rs:100:1
    |
 LL | / fn main() {
 LL | |
 LL | |
 LL | |
-...  |
+LL | |
 LL | |
 LL | | }
    | |_^

src/test/ui/hr-subtype/hr-subtype.bound_a_vs_free_x.stderr

@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/hr-subtype.rs:39:26
    |
 LL |               gimme::<$t1>(None::<$t2>);
-   |                            ^^^^^^^^^^^ one type is more general than the other
+   |                            ^^^^^^^^^^^ expected concrete lifetime, found bound lifetime parameter 'a
 ...
 LL | / check! { bound_a_vs_free_x: (for<'a> fn(&'a u32),
 LL | |                              fn(&'x u32)) }

src/test/ui/hr-subtype/hr-subtype.bound_co_a_b_vs_bound_co_a.stderr

@@ -1,14 +1,17 @@
-error: fatal error triggered by #[rustc_error]
-  --> $DIR/hr-subtype.rs:96:1
+error[E0308]: mismatched types
+  --> $DIR/hr-subtype.rs:39:26
    |
-LL | / fn main() {
-LL | |
-LL | |
-LL | |
-...  |
-LL | |
-LL | | }
-   | |_^
+LL |               gimme::<$t1>(None::<$t2>);
+   |                            ^^^^^^^^^^^ expected concrete lifetime, found bound lifetime parameter 'a
+...
+LL | / check! { bound_co_a_b_vs_bound_co_a: (for<'a,'b> fn(Co<'a>, Co<'b>),
+LL | |                                       for<'a>    fn(Co<'a>, Co<'a>)) }
+   | |______________________________________________________________________- in this macro invocation
+   |
+   = note: expected enum `std::option::Option<for<'a, 'b> fn(Co<'a>, Co<'b>)>`
+              found enum `std::option::Option<for<'a> fn(Co<'a>, Co<'a>)>`
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0308`.

src/test/ui/hr-subtype/hr-subtype.bound_co_a_co_b_ret_contra_a.stderr

@@ -1,14 +1,17 @@
-error: fatal error triggered by #[rustc_error]
-  --> $DIR/hr-subtype.rs:96:1
+error[E0308]: mismatched types
+  --> $DIR/hr-subtype.rs:39:26
    |
-LL | / fn main() {
-LL | |
-LL | |
-LL | |
-...  |
-LL | |
-LL | | }
-   | |_^
+LL |               gimme::<$t1>(None::<$t2>);
+   |                            ^^^^^^^^^^^ expected concrete lifetime, found bound lifetime parameter 'a
+...
+LL | / check! { bound_co_a_co_b_ret_contra_a: (for<'a,'b> fn(Co<'a>, Co<'b>) -> Contra<'a>,
+LL | |                                         for<'a>    fn(Co<'a>, Co<'a>) -> Contra<'a>) }
+   | |______________________________________________________________________________________- in this macro invocation
+   |
+   = note: expected enum `std::option::Option<for<'a, 'b> fn(Co<'a>, Co<'b>) -> Contra<'a>>`
+              found enum `std::option::Option<for<'a> fn(Co<'a>, Co<'a>) -> Contra<'a>>`
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0308`.

src/test/ui/hr-subtype/hr-subtype.bound_co_a_vs_bound_co_b.stderr

@@ -1,11 +1,11 @@
 error: fatal error triggered by #[rustc_error]
-  --> $DIR/hr-subtype.rs:96:1
+  --> $DIR/hr-subtype.rs:100:1
    |
 LL | / fn main() {
 LL | |
 LL | |
 LL | |
-...  |
+LL | |
 LL | |
 LL | | }
    | |_^