diff --git a/compiler/rustc_interface/src/proc_macro_decls.rs b/compiler/rustc_interface/src/proc_macro_decls.rs
index 4c236c693d0..9bf7778bfb2 100644
--- a/compiler/rustc_interface/src/proc_macro_decls.rs
+++ b/compiler/rustc_interface/src/proc_macro_decls.rs
@@ -4,21 +4,16 @@ use rustc_middle::ty::TyCtxt;
 use rustc_span::symbol::sym;
 
 fn proc_macro_decls_static(tcx: TyCtxt<'_>, (): ()) -> Option<LocalDefId> {
-    let mut finder = Finder { tcx, decls: None };
+    let mut decls = None;
 
     for id in tcx.hir().items() {
-        let attrs = finder.tcx.hir().attrs(id.hir_id());
-        if finder.tcx.sess.contains_name(attrs, sym::rustc_proc_macro_decls) {
-            finder.decls = Some(id.owner_id.def_id);
+        let attrs = tcx.hir().attrs(id.hir_id());
+        if tcx.sess.contains_name(attrs, sym::rustc_proc_macro_decls) {
+            decls = Some(id.owner_id.def_id);
         }
     }
 
-    finder.decls
-}
-
-struct Finder<'tcx> {
-    tcx: TyCtxt<'tcx>,
-    decls: Option<LocalDefId>,
+    decls
 }
 
 pub(crate) fn provide(providers: &mut Providers) {
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 33acaed435b..00242e7eed7 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -271,6 +271,10 @@ rustc_queries! {
         desc { |tcx| "elaborating item bounds for `{}`", tcx.def_path_str(key) }
     }
 
+    /// Look up all native libraries this crate depends on.
+    /// These are assembled from the following places:
+    /// - `extern` blocks (depending on their `link` attributes)
+    /// - the `libs` (`-l`) option
     query native_libraries(_: CrateNum) -> Vec<NativeLib> {
         arena_cache
         desc { "looking up the native libraries of a linked crate" }
@@ -1539,6 +1543,7 @@ rustc_queries! {
         desc { "available upstream drop-glue for `{:?}`", substs }
     }
 
+    /// Returns a list of all `extern` blocks of a crate.
     query foreign_modules(_: CrateNum) -> FxHashMap<DefId, ForeignModule> {
         arena_cache
         desc { "looking up the foreign modules of a linked crate" }
@@ -1550,9 +1555,12 @@ rustc_queries! {
     query entry_fn(_: ()) -> Option<(DefId, EntryFnType)> {
         desc { "looking up the entry function of a crate" }
     }
+
+    /// Finds the `rustc_proc_macro_decls` item of a crate.
     query proc_macro_decls_static(_: ()) -> Option<LocalDefId> {
-        desc { "looking up the derive registrar for a crate" }
+        desc { "looking up the proc macro declarations for a crate" }
     }
+
     // The macro which defines `rustc_metadata::provide_extern` depends on this query's name.
     // Changing the name should cause a compiler error, but in case that changes, be aware.
     query crate_hash(_: CrateNum) -> Svh {
@@ -1560,17 +1568,24 @@ rustc_queries! {
         desc { "looking up the hash a crate" }
         separate_provide_extern
     }
+
+    /// Gets the hash for the host proc macro. Used to support -Z dual-proc-macro.
     query crate_host_hash(_: CrateNum) -> Option<Svh> {
         eval_always
         desc { "looking up the hash of a host version of a crate" }
         separate_provide_extern
     }
+
+    /// Gets the extra data to put in each output filename for a crate.
+    /// For example, compiling the `foo` crate with `extra-filename=-a` creates a `libfoo-b.rlib` file.
     query extra_filename(_: CrateNum) -> String {
         arena_cache
         eval_always
         desc { "looking up the extra filename for a crate" }
         separate_provide_extern
     }
+
+    /// Gets the paths where the crate came from in the file system.
     query crate_extern_paths(_: CrateNum) -> Vec<PathBuf> {
         arena_cache
         eval_always
@@ -1594,6 +1609,7 @@ rustc_queries! {
         separate_provide_extern
     }
 
+    /// Get the corresponding native library from the `native_libraries` query
     query native_library(def_id: DefId) -> Option<&'tcx NativeLib> {
         desc { |tcx| "getting the native library for `{}`", tcx.def_path_str(def_id) }
     }