Rollup merge of rust-lang#137800 - BoxyUwU:param_env_docs, r=compiler-errors

Remove `ParamEnv::without_caller_bounds`

This doesn't really do anything that `ParamEnv::empty` doesn't do nowadays as `ParamEnv` *only* stores caller bounds since other information has been moved out into `TypingMode`

r? ```@compiler-errors``` ```@lcnr```

Author: matthiaskrgr

compiler/rustc_middle/src/ty/mod.rs

@@ -992,12 +992,6 @@ impl<'tcx> ParamEnv<'tcx> {
         ParamEnv { caller_bounds }
     }
 
-    /// Returns this same environment but with no caller bounds.
-    #[inline]
-    pub fn without_caller_bounds(self) -> Self {
-        Self::new(ListWithCachedTypeInfo::empty())
-    }
-
     /// Creates a pair of param-env and value for use in queries.
     pub fn and<T: TypeVisitable<TyCtxt<'tcx>>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
         ParamEnvAnd { param_env: self, value }

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -1007,7 +1007,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             // depend on its particular value in order to work, so we can clear
             // out the param env and get better caching.
             debug!("in global");
-            obligation.param_env = obligation.param_env.without_caller_bounds();
+            obligation.param_env = ty::ParamEnv::empty();
         }
 
         let stack = self.push_stack(previous_stack, &obligation);