use spans in TypeTest rather than mir::Location

Spans are independent of the body being borrow-checked, so they don't
need remapping when promoting type-tests and they yield more specific
error spans inside bodies of closures/inline consts.

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -181,7 +181,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                     // Try to convert the lower-bound region into something named we can print for the user.
                     let lower_bound_region = self.to_error_region(type_test.lower_bound);
 
-                    let type_test_span = type_test.locations.span(&self.body);
+                    let type_test_span = type_test.span;
 
                     if let Some(lower_bound_region) = lower_bound_region {
                         let generic_ty = type_test.generic_kind.to_ty(self.infcx.tcx);

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -214,8 +214,8 @@ pub struct TypeTest<'tcx> {
     /// The region `'x` that the type must outlive.
     pub lower_bound: RegionVid,
 
-    /// Where did this constraint arise and why?
-    pub locations: Locations,
+    /// The span to blame.
+    pub span: Span,
 
     /// A test which, if met by the region `'x`, proves that this type
     /// constraint is satisfied.
@@ -870,13 +870,13 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             if deduplicate_errors.insert((
                 erased_generic_kind,
                 type_test.lower_bound,
-                type_test.locations,
+                type_test.span,
             )) {
                 debug!(
                     "check_type_test: reporting error for erased_generic_kind={:?}, \
                      lower_bound_region={:?}, \
-                     type_test.locations={:?}",
-                    erased_generic_kind, type_test.lower_bound, type_test.locations,
+                     type_test.span={:?}",
+                    erased_generic_kind, type_test.lower_bound, type_test.span,
                 );
 
                 errors_buffer.push(RegionErrorKind::TypeTestError { type_test: type_test.clone() });
@@ -919,7 +919,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     ) -> bool {
         let tcx = infcx.tcx;
 
-        let TypeTest { generic_kind, lower_bound, locations, verify_bound: _ } = type_test;
+        let TypeTest { generic_kind, lower_bound, span: _, verify_bound: _ } = type_test;
 
         let generic_ty = generic_kind.to_ty(tcx);
         let Some(subject) = self.try_promote_type_test_subject(infcx, generic_ty) else {
@@ -947,7 +947,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             propagated_outlives_requirements.push(ClosureOutlivesRequirement {
                 subject,
                 outlived_free_region: static_r,
-                blame_span: locations.span(body),
+                blame_span: type_test.span,
                 category: ConstraintCategory::Boring,
             });
 
@@ -999,7 +999,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 let requirement = ClosureOutlivesRequirement {
                     subject,
                     outlived_free_region: upper_bound,
-                    blame_span: locations.span(body),
+                    blame_span: type_test.span,
                     category: ConstraintCategory::Boring,
                 };
                 debug!("try_promote_type_test: pushing {:#?}", requirement);

compiler/rustc_borrowck/src/type_check/constraint_conversion.rs

@@ -169,10 +169,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
                 .type_must_outlive(origin, t1, r2, constraint_category);
             }
 
-            GenericArgKind::Const(_) => {
-                // Consts cannot outlive one another, so we
-                // don't need to handle any relations here.
-            }
+            GenericArgKind::Const(_) => unreachable!(),
         }
     }
 
@@ -202,7 +199,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
         verify_bound: VerifyBound<'tcx>,
     ) -> TypeTest<'tcx> {
         let lower_bound = self.to_region_vid(region);
-        TypeTest { generic_kind, lower_bound, locations: self.locations, verify_bound }
+        TypeTest { generic_kind, lower_bound, span: self.span, verify_bound }
     }
 
     fn to_region_vid(&mut self, r: ty::Region<'tcx>) -> ty::RegionVid {

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -583,7 +583,6 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
         // modify their locations.
         let all_facts = &mut None;
         let mut constraints = Default::default();
-        let mut type_tests = Default::default();
         let mut liveness_constraints =
             LivenessValues::new(Rc::new(RegionValueElements::new(&promoted_body)));
         // Don't try to add borrow_region facts for the promoted MIR
@@ -594,7 +593,6 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
                 &mut this.cx.borrowck_context.constraints.outlives_constraints,
                 &mut constraints,
             );
-            mem::swap(&mut this.cx.borrowck_context.constraints.type_tests, &mut type_tests);
             mem::swap(
                 &mut this.cx.borrowck_context.constraints.liveness_constraints,
                 &mut liveness_constraints,
@@ -615,13 +613,6 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
         swap_constraints(self);
 
         let locations = location.to_locations();
-
-        // Use location of promoted const in collected constraints
-        for type_test in type_tests.iter() {
-            let mut type_test = type_test.clone();
-            type_test.locations = locations;
-            self.cx.borrowck_context.constraints.type_tests.push(type_test)
-        }
         for constraint in constraints.outlives().iter() {
             let mut constraint = constraint.clone();
             constraint.locations = locations;