Recover missing suggestion part under NLL

Author: marmeladema

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -4,6 +4,7 @@ use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed
 use rustc_infer::infer::{
     error_reporting::nice_region_error::NiceRegionError,
     error_reporting::unexpected_hidden_region_diagnostic, NllRegionVariableOrigin,
+    RelateParamBound,
 };
 use rustc_middle::hir::place::PlaceBase;
 use rustc_middle::mir::{ConstraintCategory, ReturnConstraint};
@@ -166,9 +167,11 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                     let type_test_span = type_test.locations.span(&self.body);
 
                     if let Some(lower_bound_region) = lower_bound_region {
+                        let generic_ty = type_test.generic_kind.to_ty(self.infcx.tcx);
+                        let origin = RelateParamBound(type_test_span, generic_ty, None);
                         self.buffer_error(self.infcx.construct_generic_bound_failure(
                             type_test_span,
-                            None,
+                            Some(origin),
                             type_test.generic_kind,
                             lower_bound_region,
                             self.body.source.def_id().as_local(),

src/test/ui/nll/closure-requirements/propagate-from-trait-match.stderr

@@ -47,7 +47,7 @@ LL | |         // This function call requires that
 ...  |
 LL | |         require(value);
 LL | |     });
-   | |_____^
+   | |_____^ ...so that the type `T` will meet its required lifetime bounds
 
 error: aborting due to previous error
 

src/test/ui/nll/ty-outlives/impl-trait-outlives.stderr

@@ -5,7 +5,7 @@ LL | fn no_region<'a, T>(x: Box<T>) -> impl Debug + 'a
    |                  - help: consider adding an explicit lifetime bound...: `T: 'a`
 ...
 LL |     x
-   |     ^
+   |     ^ ...so that the type `T` will meet its required lifetime bounds
 
 error[E0309]: the parameter type `T` may not live long enough
   --> $DIR/impl-trait-outlives.rs:26:5
@@ -14,7 +14,7 @@ LL | fn wrong_region<'a, 'b, T>(x: Box<T>) -> impl Debug + 'a
    |                         - help: consider adding an explicit lifetime bound...: `T: 'a`
 ...
 LL |     x
-   |     ^
+   |     ^ ...so that the type `T` will meet its required lifetime bounds
 
 error: aborting due to 2 previous errors
 

src/test/ui/nll/ty-outlives/projection-implied-bounds.stderr

@@ -4,7 +4,7 @@ error[E0310]: the parameter type `T` may not live long enough
 LL | fn generic2<T: Iterator>(value: T) {
    |             -- help: consider adding an explicit lifetime bound...: `T: 'static +`
 LL |     twice(value, |value_ref, item| invoke2(value_ref, item));
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
 
 error: aborting due to previous error
 

src/test/ui/nll/ty-outlives/projection-no-regions-closure.stderr

@@ -33,6 +33,7 @@ LL |     with_signature(x, |mut y| Box::new(y.next()))
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding an explicit lifetime bound `<T as Iterator>::Item: 'a`...
+   = note: ...so that the type `<T as Iterator>::Item` will meet its required lifetime bounds
 
 note: external requirements
   --> $DIR/projection-no-regions-closure.rs:34:23
@@ -96,6 +97,7 @@ LL |     with_signature(x, |mut y| Box::new(y.next()))
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding an explicit lifetime bound `<T as Iterator>::Item: 'a`...
+   = note: ...so that the type `<T as Iterator>::Item` will meet its required lifetime bounds
 
 note: external requirements
   --> $DIR/projection-no-regions-closure.rs:52:23

src/test/ui/nll/ty-outlives/projection-no-regions-fn.stderr

@@ -5,6 +5,7 @@ LL |     Box::new(x.next())
    |     ^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding an explicit lifetime bound `<T as Iterator>::Item: 'a`...
+   = note: ...so that the type `<T as Iterator>::Item` will meet its required lifetime bounds
 
 error[E0309]: the associated type `<T as Iterator>::Item` may not live long enough
   --> $DIR/projection-no-regions-fn.rs:28:5
@@ -13,6 +14,7 @@ LL |     Box::new(x.next())
    |     ^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding an explicit lifetime bound `<T as Iterator>::Item: 'a`...
+   = note: ...so that the type `<T as Iterator>::Item` will meet its required lifetime bounds
 
 error: aborting due to 2 previous errors
 

src/test/ui/nll/ty-outlives/projection-one-region-closure.stderr

@@ -35,7 +35,7 @@ LL | fn no_relationships_late<'a, 'b, T>(cell: Cell<&'a ()>, t: T)
    |                                  - help: consider adding an explicit lifetime bound...: `T: 'a`
 ...
 LL |     with_signature(cell, t, |cell, t| require(cell, t));
-   |                             ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                             ^^^^^^^^^^^^^^^^^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
 
 error: lifetime may not live long enough
   --> $DIR/projection-one-region-closure.rs:45:39
@@ -86,7 +86,7 @@ LL | fn no_relationships_early<'a, 'b, T>(cell: Cell<&'a ()>, t: T)
    |                                   - help: consider adding an explicit lifetime bound...: `T: 'a`
 ...
 LL |     with_signature(cell, t, |cell, t| require(cell, t));
-   |                             ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                             ^^^^^^^^^^^^^^^^^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
 
 error: lifetime may not live long enough
   --> $DIR/projection-one-region-closure.rs:56:39

src/test/ui/nll/ty-outlives/projection-two-region-trait-bound-closure.stderr

@@ -34,6 +34,7 @@ LL |     with_signature(cell, t, |cell, t| require(cell, t));
    |                             ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding an explicit lifetime bound `<T as Anything<ReEarlyBound(0, 'b), ReEarlyBound(1, 'c)>>::AssocType: 'a`...
+   = note: ...so that the type `<T as Anything<ReEarlyBound(0, 'b), ReEarlyBound(1, 'c)>>::AssocType` will meet its required lifetime bounds
 
 note: external requirements
   --> $DIR/projection-two-region-trait-bound-closure.rs:48:29
@@ -70,6 +71,7 @@ LL |     with_signature(cell, t, |cell, t| require(cell, t));
    |                             ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding an explicit lifetime bound `<T as Anything<ReEarlyBound(1, 'b), ReEarlyBound(2, 'c)>>::AssocType: 'a`...
+   = note: ...so that the type `<T as Anything<ReEarlyBound(1, 'b), ReEarlyBound(2, 'c)>>::AssocType` will meet its required lifetime bounds
 
 note: external requirements
   --> $DIR/projection-two-region-trait-bound-closure.rs:61:29

src/test/ui/nll/ty-outlives/projection-where-clause-none.stderr

@@ -5,7 +5,7 @@ LL | fn foo<'a, T>() -> &'a ()
    |            - help: consider adding an explicit lifetime bound...: `T: 'a`
 ...
 LL |     bar::<T::Output>()
-   |     ^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
 
 error: aborting due to previous error
 

src/test/ui/nll/ty-outlives/ty-param-closure-approximate-lower-bound.stderr

@@ -55,7 +55,7 @@ error[E0309]: the parameter type `T` may not live long enough
 LL | fn generic_fail<'a, T>(cell: Cell<&'a ()>, value: T) {
    |                     - help: consider adding an explicit lifetime bound...: `T: 'a`
 LL |     twice(cell, value, |a, b| invoke(a, b));
-   |                        ^^^^^^^^^^^^^^^^^^^
+   |                        ^^^^^^^^^^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
 
 error: aborting due to previous error