Rollup merge of #88030 - fee1-dead:fixme, r=oli-obk

Assign FIXMEs to me and remove obsolete ones

Also fixed capitalization of documentation

We also don't need to transform predicates to be non-const since we basically ignore const predicates in non-const contexts.

r? `````@oli-obk`````

Author: m-ou-se

compiler/rustc_infer/src/traits/engine.rs

@@ -63,7 +63,7 @@ pub trait TraitEngine<'tcx>: 'tcx {
         infcx: &InferCtxt<'_, 'tcx>,
     ) -> Result<(), Vec<FulfillmentError<'tcx>>>;
 
-    // FIXME this should not provide a default body for chalk as chalk should be updated
+    // FIXME(fee1-dead) this should not provide a default body for chalk as chalk should be updated
     fn select_with_constness_where_possible(
         &mut self,
         infcx: &InferCtxt<'_, 'tcx>,

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

@@ -316,7 +316,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         self.infcx.tcx
     }
 
-    /// returns `true` if the predicate is considered `const` to
+    /// Returns `true` if the predicate is considered `const` to
     /// this selection context.
     pub fn is_predicate_const(&self, pred: ty::Predicate<'_>) -> bool {
         match pred.kind().skip_binder() {

compiler/rustc_traits/src/type_op.rs

@@ -6,9 +6,7 @@ use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
 use rustc_infer::traits::TraitEngineExt as _;
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::subst::{GenericArg, Subst, UserSelfTy, UserSubsts};
-use rustc_middle::ty::{
-    self, FnSig, Lift, PolyFnSig, PredicateKind, Ty, TyCtxt, TypeFoldable, Variance,
-};
+use rustc_middle::ty::{self, FnSig, Lift, PolyFnSig, Ty, TyCtxt, TypeFoldable, Variance};
 use rustc_middle::ty::{ParamEnv, ParamEnvAnd, Predicate, ToPredicate};
 use rustc_span::DUMMY_SP;
 use rustc_trait_selection::infer::InferCtxtBuilderExt;
@@ -87,16 +85,7 @@ impl AscribeUserTypeCx<'me, 'tcx> {
         Ok(())
     }
 
-    fn prove_predicate(&mut self, mut predicate: Predicate<'tcx>) {
-        if let PredicateKind::Trait(mut tr) = predicate.kind().skip_binder() {
-            if let hir::Constness::Const = tr.constness {
-                // FIXME check if we actually want to prove const predicates inside AscribeUserType
-                tr.constness = hir::Constness::NotConst;
-                predicate =
-                    predicate.kind().rebind(PredicateKind::Trait(tr)).to_predicate(self.tcx());
-            }
-        }
-
+    fn prove_predicate(&mut self, predicate: Predicate<'tcx>) {
         self.fulfill_cx.register_predicate_obligation(
             self.infcx,
             Obligation::new(ObligationCause::dummy(), self.param_env, predicate),

library/alloc/tests/const_fns.rs

@@ -10,7 +10,7 @@ pub const MY_VEC: Vec<usize> = Vec::new();
 #[allow(dead_code)]
 pub const MY_STRING: String = String::new();
 
-// FIXME remove this struct once we put `K: ?const Ord` on BTreeMap::new.
+// FIXME(fee1-dead) remove this struct once we put `K: ?const Ord` on BTreeMap::new.
 #[derive(PartialEq, Eq, PartialOrd)]
 pub struct MyType;
 

library/alloc/tests/lib.rs

@@ -25,8 +25,6 @@
 #![feature(string_remove_matches)]
 #![feature(const_btree_new)]
 #![feature(const_trait_impl)]
-// FIXME remove this when const_trait_impl is not incomplete anymore
-#![allow(incomplete_features)]
 
 use std::collections::hash_map::DefaultHasher;
 use std::hash::{Hash, Hasher};