Improve contracts intrisics and remove wrapper function

1. Document the new intrinsics.
2. Make the intrinsics actually check the contract if enabled, and
   remove `contract::check_requires` function.
3. Use panic with no unwind in case contract is using to check for
   safety, we probably don't want to unwind. Following the same
   reasoning as UB checks.

1 files changed, 4 insertions, 6 deletions

diff --git a/compiler/rustc_hir_analysis/src/check/intrinsic.rs b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
index 6c0cebccefd..e641fb0fb62 100644
--- a/compiler/rustc_hir_analysis/src/check/intrinsic.rs
+++ b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
@@ -223,17 +223,15 @@ pub fn check_intrinsic_type(
         };
         (n_tps, 0, 0, inputs, output, hir::Safety::Unsafe)
     } else if intrinsic_name == sym::contract_check_ensures {
-        // contract_check_ensures::<'a, Ret, C>(&'a Ret, C) -> bool
+        // contract_check_ensures::<'a, Ret, C>(&'a Ret, C)
         // where C: impl Fn(&'a Ret) -> bool,
         //
-        // so: two type params, one lifetime param, 0 const params, two inputs, returns boolean
+        // so: two type params, one lifetime param, 0 const params, two inputs, no return
 
         let p = generics.param_at(0, tcx);
         let r = ty::Region::new_early_param(tcx, p.to_early_bound_region_data());
         let ref_ret = Ty::new_imm_ref(tcx, r, param(1));
-        // let br = ty::BoundRegion { var: ty::BoundVar::ZERO, kind: ty::BrAnon };
-        // let ref_ret = Ty::new_imm_ref(tcx, ty::Region::new_bound(tcx, ty::INNERMOST, br), param(0));
-        (2, 1, 0, vec![ref_ret, param(2)], tcx.types.bool, hir::Safety::Safe)
+        (2, 1, 0, vec![ref_ret, param(2)], tcx.types.unit, hir::Safety::Safe)
     } else {
         let safety = intrinsic_operation_unsafety(tcx, intrinsic_id);
         let (n_tps, n_cts, inputs, output) = match intrinsic_name {
@@ -628,7 +626,7 @@ pub fn check_intrinsic_type(
             // contract_checks() -> bool
             sym::contract_checks => (0, 0, Vec::new(), tcx.types.bool),
             // contract_check_requires::<C>(C) -> bool, where C: impl Fn() -> bool
-            sym::contract_check_requires => (1, 0, vec![param(0)], tcx.types.bool),
+            sym::contract_check_requires => (1, 0, vec![param(0)], tcx.types.unit),
 
             sym::simd_eq
             | sym::simd_ne