Add documentation for some queries

Author: Noratrieb

compiler/rustc_middle/src/query/mod.rs

@@ -109,10 +109,12 @@ pub use plumbing::{IntoQueryParam, TyCtxtAt, TyCtxtEnsure, TyCtxtEnsureWithValue
 // Queries marked with `fatal_cycle` do not need the latter implementation,
 // as they will raise an fatal error on query cycles instead.
 rustc_queries! {
+    /// This exists purely for testing the interactions between delay_span_bug and incremental.
     query trigger_delay_span_bug(key: DefId) -> () {
-        desc { "triggering a delay span bug" }
+        desc { "triggering a delay span bug for testing incremental" }
     }
 
+    /// Collects the list of all tools registered using `#![register_tool]`.
     query registered_tools(_: ()) -> &'tcx ty::RegisteredTools {
         arena_cache
         desc { "compute registered tools for crate" }
@@ -286,6 +288,7 @@ rustc_queries! {
         }
     }
 
+    /// The root query triggering all analysis passes like typeck or borrowck.
     query analysis(key: ()) -> Result<(), ErrorGuaranteed> {
         eval_always
         desc { "running analysis passes on this crate" }
@@ -1785,10 +1788,17 @@ rustc_queries! {
         desc { "calculating the missing lang items in a crate" }
         separate_provide_extern
     }
+
+    /// The visible parent map is a map from every item to a visible parent.
+    /// It prefers the shortest visible path to an item.
+    /// Used for diagnostics, for example path trimming.
+    /// The parents are modules, enums or traits.
     query visible_parent_map(_: ()) -> &'tcx DefIdMap<DefId> {
         arena_cache
         desc { "calculating the visible parent map" }
     }
+    /// Collects the "trimmed", shortest accessible paths to all items for diagnostics.
+    /// See the [provider docs](`rustc_middle::ty::print::trimmed_def_paths`) for more info.
     query trimmed_def_paths(_: ()) -> &'tcx FxHashMap<DefId, Symbol> {
         arena_cache
         desc { "calculating trimmed def paths" }